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December 2005

Volume 76, Issue 12,  Articles (12xxxx)

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INVITED ARTICLE

Implementation of a modern resonant ultrasound spectroscopy system for the measurement of the elastic moduli of small solid specimens

Albert Migliori and J. D. Maynard

Rev. Sci. Instrum. 76, 121301 (2005) (7 pages)

Online Publication Date: 29 December 2005

Full Text: PDF (459 kB)

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The use of mechanical resonances to determine the elastic moduli of materials of interest to condensed-matter physics, engineering, materials science and more is a steadily evolving process. With the advent of massive computing capability in an ordinary personal computer, it is now possible to find all the elastic moduli of low-symmetry solids using sophisticated analysis of a set of the lowest resonances. This process, dubbed "resonant ultrasound spectroscopy" or RUS, provides the highest absolute accuracy of any routine elastic modulus measurement technique, and it does this quickly on small samples. RUS has been reviewed extensively elsewhere, but still lacking is a complete description of how to make such measurements with hardware and software easily available to the general science community. In this article, we describe how to implement realistically a useful RUS system.
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87.50.Kk
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OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Long-term stabilization of the length of an optical reference cavity

Gaëtan Hagel, Marie Houssin, Martina Knoop, Caroline Champenois, Michel Vedel, and Fernande Vedel

Rev. Sci. Instrum. 76, 123101 (2005) (4 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (313 kB)

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To obtain a high degree of long-term length stabilization of an optical reference cavity, its free-spectral range is locked by means of an accurate and stable frequency synthesizer. The locking scheme is twofold: a laser is locked on the Nth mode of a reference Fabry-Perot cavity and part of the laser light is shifted in frequency to be in resonance with the (N+1)th mode of the cavity. This shift is generated by an acousto-optical modulator (AOM) mounted in a double-pass scheme, matching half of the free-spectral range of the reference cavity. The resulting absolute stabilization of the length of the cavity reaches the 10–11 level per second, limited by the lock transfer properties and the frequency stability of the AOM control synthesizer.
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42.60.Lh, 42.60.Da, 42.60.Fc, 42.79.Hp, 42.79.Jq

Polarization mode dispersion: Characterization of optical fiber using cross-correlation interferometry

T. B. Gibbon, A. B. Conibear, and A. W. R. Leitch

Rev. Sci. Instrum. 76, 123102 (2005) (3 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (68 kB)

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The interferometric measurement technique is known to be a quick and reliable method for accurately measuring polarization mode dispersion (PMD) in an optical fiber. In this paper we present the means by which this technique may further be used to obtain qualitative information about the birefringent properties of the fiber under test. Polarization maintaining fiber segments are used to show that a concatenation of n birefringent segments gives rise to an interferogram with 3n interference peaks. The peak positions are further related to the total birefringent contribution of each of the fiber segments. These findings are then used to interpret measurement results and comment on the PMD and related birefringent properties of numerous single mode fibers. Stress is shown to introduce PMD in uncabled single mode fiber. Interferometric measurements are also used to determine the number of birefringent segments in both undeployed and deployed cabled fibers. Polarization optical time domain reflectometry is used successfully to verify these results.
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42.81.Cn, 42.81.Gs, 42.81.Dp, 07.60.Ly, 07.60.Hv

Slice imaging of photodissociation of spatially oriented molecules

M. Laura Lipciuc, Alrik J. van den Brom, Laura Dinu, and Maurice H. M. Janssen

Rev. Sci. Instrum. 76, 123103 (2005) (7 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (502 kB)

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An electrostatic ion lens to spatially orient parent molecules and to image the angular distribution of photofragments is presented. Photodissociation of laboratory-oriented molecules makes it possible to study the dynamics of the dissociation process in more detail compared to photodissociation of nonoriented molecules. Using the velocity map imaging technique in combination with the slice imaging technique, the spatial recoil distribution of the photofragments can be measured with high resolution and without symmetry restrictions. Insertion of orientation electrodes between the repeller and the extractor of a velocity mapping electrostatic lens severely distorts the ion trajectories. The position where the ions are focused by the lens, the focal length, can be very different in the directions parallel and perpendicular to the inserted orientation electrodes. The focal length depends on the exact dimensions and positions of the electrodes of the ion lens. As this dependence is different in both directions, this dependence can be used to correct for the distorted ion trajectories. We discuss the design of an electrostatic ion lens, which is able to orient parent molecules and map the velocity of the photofragments. We report sliced images of photofragments from photolysis of spatially oriented CD3I molecules to demonstrate the experimental combination of molecular orientation and velocity map slice imaging with good resolution.
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41.85.Ne, 33.80.Gj, 82.50.-m, 39.10.+j

A microbeam wavelength-dispersive x-ray fluorescence system and its application for thin-film analysis

Ning Gao, Zewu Chen, and Qifan Xiao

Rev. Sci. Instrum. 76, 123104 (2005) (5 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (135 kB)

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A low-power wavelength dispersive x-ray fluorescence (WDXRF) system with a spatial resolution of 25  µm has been built to measure thin-film thickness. By using advanced x-ray optics and a 50-W air-cooled x-ray tube, the system achieved a detection limit equivalent to that of a conventional WDXRF system that employs a 4-kW x-ray tube and a spatial resolution of 10  mm in diameter. For a 25-nm-thick tantalum underlayer, a detection limit of 0.18  nm was achieved and measurement precision of 2% was obtained with a measurement time of 100  s.
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07.85.-m, 82.80.Ej

Compact high-resolution spectral phase shaper

S. Postma, P. van der Walle, H. L. Offerhaus, and N. F. van Hulst

Rev. Sci. Instrum. 76, 123105 (2005) (4 pages)

Online Publication Date: 14 December 2005

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The design and operation of a high-resolution spectral phase shaper with a footprint of only 7×10  cm2 is presented. The liquid-crystal modulator has 4096 elements. More than 600 independent degrees of freedom can be positioned with a relative accuracy of 1  pixel. The spectral shaping of pulses from a broadband Ti:sapphire laser is verified by a hybrid cross-frequency-resolved optical gating/Grenouille measurement and intensity autocorrelation. We demonstrate the ability to split one pulse into two or more pulses with a programmable delay of more than 8.5  ps. To our knowledge this represents the most compact high resolution device in liquid-crystal modulator-based shaping to this date.
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41.85.Ct, 42.60.Fc, 42.65.Re, 42.79.Hp

Focused-laser interferometric position sensor

Stephen J. Friedman, Brett Barwick, and Herman Batelaan

Rev. Sci. Instrum. 76, 123106 (2005) (5 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (295 kB)

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We describe a simple method to measure the position shifts of an object with a range of tens of micrometers using a focused-laser (FL) interferometric position sensor. In this article we examine the effects of mechanical vibration on FL and Michelson interferometers. We tested both interferometers using vibration amplitudes ranging from 0 to 20  µm. Our FL interferometer has a resolution much better than the diffraction grating periodicities of 10 and 14  µm used in our experiments. A FL interferometer provides improved mechanical stability at the expense of spatial resolution. Our experimental results show that Michelson interferometers cannot be used when the vibration amplitude is more than an optical wavelength. The main purpose of this article is to demonstrate that a focused-laser interferometric position sensor can be used to measure the position shifts of an object on a less sensitive, micrometer scale when the vibration amplitude is too large to use a Michelson interferometer.
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42.79.Pw, 06.30.Bp, 07.60.Ly, 42.79.Qx

Diffraction efficiency and diffraction bandwidth of thermal-gradient and composition-gradient crystals

R. Smither, K. Abu Saleem, M. Beno, C. Kurtz, A. Khounsary, and N. Abrosimov

Rev. Sci. Instrum. 76, 123107 (2005) (19 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (1039 kB)

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Measurements were made at the Advanced Photon Source at Argonne National Laboratory on the diffraction efficiency and diffraction bandwidth of a thermal-gradient crystal (Si) and a composition-gradient crystal (Si-Ge) to which a thermal gradient was applied. Gradient crystals are crystals in which the spacing between crystalline planes varies with the position in the crystal. This change in the crystal plane spacing is obtained by applying a thermal gradient to a single crystal or by growing a two-component crystal in which the ratio of the two components changes with position in the crystal. Measurements were made at two energies, 92.6 and 153 keV. Both crystals were 1-cm cubes. Laue diffraction (transmission diffraction) was used in all experiments. The thermal gradient was applied perpendicular to the [111] diffraction planes of the pure silicon crystal and perpendicular the [400] diffraction planes in the composition-gradient crystal (Si-Ge). The thermal gradient applied to the crystals was quite uniform. This resulted in nearly spherical surfaces for the crystalline planes. Changing the value of the thermal gradient applied to the crystals changed the radius of curvature of the spherical surface. The thermal gradients were varied between 0.0 and 114  °C/cm, resulting in radii of curvature from near infinity down to 40 m. By adjusting the thermal gradient applied to the crystals, one obtained diffraction efficiencies between 0.90 and 0.95 and bandwidths of up to 100 arc sec. The diffraction efficiency in the Laue geometry is defined as the ratio of the intensity of the diffracted beam to the intensity of the undiffracted beam that passes through the crystal when there is no diffraction. The length of the crystal traversed by the x-ray beam was 1.0 cm in all cases.
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61.10.Nz

Fast and compact multichannel photon coincidence unit for quantum information processing

Sascha Gaertner, Harald Weinfurter, and Christian Kurtsiefer

Rev. Sci. Instrum. 76, 123108 (2005) (6 pages)

Online Publication Date: 21 December 2005

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We present a fast and compact multichannel coincidence unit to count all possible single and coincidence detection events in an experiment with eight single-photon detectors at once. Using high-speed electronics and a microcontroller, this device is able to process up to 800  000  events/s. The coincidence window can be tuned within a range of 4–12  ns. The device can be easily scaled to any number of input channels and is thus ideally suited for efficient multiphoton quantum information processing.
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42.50.-p, 42.30.-d, 03.67.Hk, 03.67.Lx

GaP THz wave generator and THz spectrometer using Cr:Forsterite lasers

Ken Suto, Tetsuo Sasaki, Tadao Tanabe, Kyosuke Saito, Jun-ichi Nishizawa, and Masahiko Ito

Rev. Sci. Instrum. 76, 123109 (2005) (3 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (270 kB)

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We have developed a type of THz wave generator that uses Cr:Forsterite lasers as the pump and signal sources for difference frequency generation in GaP (Cr:F source system). We confirmed the generation of THz waves in the frequency range from 0.3  to  7.5  THz, which is just similar to that obtained using the THz wave generator previously developed utilizing yttrium aluminum garnet and optical parametric oscillator (OPO) lasers (OPO source system). A peak output power of 100  mW was obtained from 1.2  to  5  THz when the power of the two input beams was 3  mJ each, similar to the OPO source system. A wide measurable frequency range from below 0.6  THz to over 6  THz was obtained by using the Cr:F source system as the light source of a spectrometer, which has the merits of simple structure, easy maintenance, and low cost compared with the OPO source system. Although the linewidth of the Cr:F source system is greater than that of the OPO source system, the THz spectrometer still has sufficient resolution for measuring solids or liquids at room temperature.
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07.57.-c, 42.65.Hw, 63.20.Dj, 87.64.-t

High-temperature calcium vapor cell for spectroscopy on the 4s2  1S0–4s4p  3P1 intercombination line

Christopher J. Erickson, Brian Neyenhuis, and Dallin S. Durfee

Rev. Sci. Instrum. 76, 123110 (2005) (5 pages)

Online Publication Date: 27 December 2005

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We have demonstrated a high-temperature vapor cell for absorption spectroscopy on the Ca intercombination line. The cell uses a dual-chamber design to achieve the high temperatures necessary for an optically dense vapor while avoiding the necessity of high-temperature vacuum valves and glass-to-metal seals. We have observed over 50% absorption in a single pass through the cell. Although pressure broadening in the cell prevented us from performing saturated-absorption spectroscopy, the broadening resulted in higher signal-to-noise ratios by allowing us to probe the atoms with intensities much greater than the 0.2  µW/cm2 saturation intensity of the unbroadened transition. The techniques presented in this article could easily be applied to study other transitions in a variety of atomic species.
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07.60.Rd, 42.65.-k

Anomalous attenuation at low temperatures in high-intensity helium beam sources

H. Hedgeland, A. P. Jardine, W. Allison, and J. Ellis

Rev. Sci. Instrum. 76, 123111 (2005) (5 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (284 kB)

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High-intensity supersonic helium beam sources are a critical component in modern thermal energy helium atom scattering apparatuses. In common with sources developed elsewhere, we have observed beam attenuation at low temperature as the helium flow through the nozzle is increased. A detailed analysis of the measurements demonstrates that direct backscattering in the nozzle-skimmer region is likely to be the major attenuation source. A numerical model, which describes the principle sources of scattering in the region between source and skimmer, is shown to provide a good description of the experimental data for a range of flow conditions and for stagnation temperatures between 37 and 300  K. The model includes partial accommodation of atoms scattered from surfaces of the skimmer and chamber, together with a realistic scattering potential. We use the model to predict the effect of various geometric alterations, aimed at improving the ultimate beam intensity.
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39.10.+j, 34.50.Dy

Evaluation of the sensitivity to mechanical vibrations of an IR Fourier spectrometer

L. Comolli and B. Saggin

Rev. Sci. Instrum. 76, 123112 (2005) (8 pages)

Online Publication Date: 27 December 2005

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This article presents an experimental and theoretical investigation of the sensitivity to mechanical disturbances of a Fourier-transform infrared spectrometer, the Planetary Fourier Spectrometer, currently orbiting around Mars onboard ESA Mars Express orbiter. A theoretical analysis has been performed in order to highlight the expected effects of the vibrations, then laboratory tests have been designed and carried out for instrument characterization. The two classical types of disturbance effects were expected in the case of mechanical vibrations: the interfering type, leading to an additive contribution to the interferograms, and the modifying type, which changes the interferometer sensitivity. Both effects have been evidenced in the experimental tests and the instrument sensitivity derived; moreover, the effects on the spectra, which are the Fourier transform of interferograms, are highlighted and characterized. The effects of both harmonic and random broadband spectrum disturbances have been considered. While the broadband disturbances increase uniformly the noise, harmonic disturbances produce localized effects in the spectra and replicas of the spectral features with wave-number shifts proportional to disturbance frequency. It has also been highlighted that, the disturbances from mechanical vibrations being uncorrelated with the interferometric signals, by spectrum averaging, like all the other noise sources, they can be reduced. Methods for spectrum diagnostics and for increasing the signal-to-noise ratio in vibration-affected spectra are proposed as well.
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07.57.Ty, 95.55.Qf, 95.55.Br, 07.60.Ly, 42.30.Kq, 42.87.-d
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PARTICLE SOURCES, OPTICS AND ACCELERATION; PARTICLE DETECTORS

Compact 300  keV electron gun for radiation processing

L. Auditore, R. C. Barnà, D. De Pasquale, S. Interdonato, A. Italiano, A. Trifiró, and M. Trimarchi

Rev. Sci. Instrum. 76, 123301 (2005) (4 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (383 kB)

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A new self-shielded system for surface radiation treatments has been developed, based on a 300  keV electron gun, able to irradiate a 100  mm×10  mm area. The compact and durable system described in this paper provides the required dose of treatment for several industrial or scientific research applications, with a good reproducibility of the parameters.
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29.25.Bx, 87.50.Gi
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NUCLEAR PHYSICS, FUSION AND PLASMAS

An upgraded 32-channel heterodyne electron cyclotron emission radiometer on Tore Supra

J. L. Ségui et al. (Tore Supra Team)

Rev. Sci. Instrum. 76, 123501 (2005) (6 pages)

Online Publication Date: 14 December 2005

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A 32-channel, 1  GHz spaced heterodyne radiometer is used on the Tore Supra tokamak to measure electron cyclotron emission (ECE) in the frequency range 78–110  GHz for the ordinary mode (O:E||B,k[perpendicular]B) and 94–126  GHz for the extraordinary mode (X:E[perpendicular]B,k[perpendicular]B). The radial resolution is essentially limited by ECE relativistic effects, depending on electron temperature and density, and not by the channels' frequency spacing. The time resolution depends on the acquisition scheme: the system allows for both 1  ms and 10  µs acquisition. For example, this leads to precise electron temperature mapping during MHD activity. First experimental results obtained with this upgraded 32-channel radiometer are presented.
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52.70.Gw, 07.57.Kp, 52.55.Fa, 52.25.Os, 52.27.Ny, 52.30.Cv
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MICROSCOPY AND IMAGING

A multiaxis stage configured for rapid observations of plane samples at multiple angles

Michael Lamvik and Sonia Grego

Rev. Sci. Instrum. 76, 123701 (2005) (3 pages)

Online Publication Date: 14 December 2005

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We describe a mechanical configuration that allows any point on a flat sample to be moved to any angle of tilt and rotation (within the limits of which the stage is capable) while maintaining the area of interest at a constant focus and within the field of view of a fixed optical system. We describe eight axes of movement required to obtain the desired stability of focus and view area. We demonstrate the proposed concept by assembling an instrument using mostly existing parts. This optical-microscope-based instrument allows sample tilts to 60° and unlimited rotation while maintaining the point of interest within better than 17  µm in x, y, and z of the center of the field of view of a 100× optical system.
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07.60.Pb, 42.15.Eq

A multiphoton laser scanning microscope setup for transcranial in vivo brain imaging on mice

Gabriele Nase, P. Johannes Helm, Trond Reppen, and Ole Petter Ottersen

Rev. Sci. Instrum. 76, 123702 (2005) (5 pages)

Online Publication Date: 14 December 2005

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We describe a multiphoton laser scanning microscope setup for transcranial in vivo brain imaging in mice. The modular system is based on a modified industrial standard Confocal Scanning Laser Microscope (CSLM) and is assembled mainly from commercially available components. A special multifunctional stage, which is optimized for both laser scanning microscopic observation and preparative animal surgery, has been developed and built. The detection unit includes a highly efficient photomultiplier tube installed in a Peltier-cooled thermal box shielding the detector from changes in room temperature and from distortions caused by external electromagnetic fields. The images are recorded using a 12-bit analog–to–digital converter. Depending on the characteristics of the staining, individual nerve cells can be imaged down to at least 100  µm below the intact cranium and down to at least 200  µm below the opened cranium.
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87.63.Lk, 42.62.Be, 07.60.Pb, 87.19.La

Electron-beam tip/sample heating device for a scanning tunneling microscopy

H. F. Ding, J. E. Pearson, Dongqi Li, Ruihua Cheng, F. Y. Fradin, and S. D. Bader

Rev. Sci. Instrum. 76, 123703 (2005) (4 pages)

Online Publication Date: 21 December 2005

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We present an electron-beam heating device for a scanning tunneling microscopy (STM) that can be used for heating both the STM tip and the sample to 2200  K. Mounted on a linear bellows with electrical feedthroughs, the device can be readily installed into the transfer path of a vacuum load lock. We demonstrate the heating capability of the device by flash cleaning Ru(0001) and Fe(001) crystals, and W tips. The flash-cleaned W tips are coated with Fe and further used for spin-polarized imaging of the Mn/Fe(001) system.
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07.79.Cz

An atomic force microscope tip as a light source

Valentin Lulevich, Chris Honig, and William A. Ducker

Rev. Sci. Instrum. 76, 123704 (2005) (5 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (404 kB)

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We present a simple method for causing the end of a silicon nitride atomic force microscope (AFM) tip to emit light, and we use this emitted light to perform scanning near-field optical microscopy. Illumination of a silicon nitride AFM tip by blue (488  nm) or green (532  nm) laser light causes the sharp part of the tip to emit orange light. Orange light is emitted when the tip is immersed in either air or water; and while under illumination, emission continues for a period of many hours without photobleaching. By careful alignment of the incident beam, we can arrange the scattered light to decay as a function of the tip-substrate separation with a decay length of 100–200  nm. The exponential decay of the intensity means that the emitted light is dominated by contributions from parts of the tip that are near the sample, and therefore the emitted orange light can be used to capture high-resolution near-field optical images in air or water.
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07.79.Lh, 42.72.-g, 78.55.Hx
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CONDENSED MATTER; MATERIALS

Eucentric four-axis ultrahigh vacuum goniometer for reflection high-energy electron diffraction applications

A. Schmehl, R. R. Schulz, and J. Mannhart

Rev. Sci. Instrum. 76, 123901 (2005) (4 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (183 kB)

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The design and performance of a four-axis low-profile eucentric UHV goniometer for in situ reflection high-energy electron diffraction (RHEED) studies during film deposition is reported. The design provides one translational and three rotational degrees of freedom that are fully independent. Although developed to facilitate high-pressure RHEED during the growth of oxide thin films by pulsed laser deposition, this goniometer design is applicable to other UHV techniques including molecular beam epitaxy. The goniometer requires only a single DN 100 CF flange (6  in. o.d., 100  mm i.d.), making it suitable for small deposition systems, too. Samples, attached to a resistively heated holder, can be easily transferred on and off of the goniometer without breaking vacuum. The holder accommodates samples up to 10  mm×10  mm in size and allows them to be heated to 900  °C in pure oxygen while being attached to the goniometer. Full eucentric motion of the hot sample is possible with a typical axis precision of <0.1°. Most of the mechanism is located in air, allowing the use of standard materials and lubricants, substantially reducing the in-vacuum mechanics, and increasing the precision, reliability, and robustness of the system.
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07.85.-m, 07.35.+k, 81.15.Fg, 81.15.Hi

Composite bimetallic gasket and compact mechanical anvil retainer for magnetic measurements in a diamond-anvil cell to 30  GPa

Mamoru Ishizuka

Rev. Sci. Instrum. 76, 123902 (2005) (4 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (197 kB)

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A composite gasket was designed for diamond-anvil cells where the load was supported mainly by the inner part made of NiCrAl with a diameter slightly larger than the culet of the anvil. A BeCu girdle encased the NiCrAl washer and prevented it from fracturing. The thickness of the gasket was about 30  µm at a pressure of 30  GPa applied with a pair of diamond anvils having 500 and 550  µm culets. The magnetic contribution of the composite gasket to the background signal was almost the same as that of a BeCu gasket having the same size. The diamond anvils were fixed to the pistons with four miniature screws through small BeCu rings that were press fitted to the circumference of the diamond anvils. The performance of this composite gasket together with the anvil retainer was illustrated by the measurements of the temperature dependence of the dc magnetic susceptibility of Cs2CuF4 under various pressures up to 26  GPa using a superconducting quantum interference device vibrating coil magnetometer.
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07.55.-w, 07.35.+k, 75.30.Cr

Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts

Z. Zhao, T. Diemant, T. Häring, H. Rauscher, and R. J. Behm

Rev. Sci. Instrum. 76, 123903 (2005) (8 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (422 kB)

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We describe the design and performance of a high-pressure reaction cell for simultaneous kinetic and in situ infrared reflection (IR) spectroscopic measurements on model catalysts at elevated pressures, between 10–3 and 103  mbars, which can be operated both as batch reactor and as flow reactor with defined gas flow. The cell is attached to an ultrahigh-vacuum (UHV) system, which is used for sample preparation and also contains facilities for sample characterization. Specific for this design is the combination of a small cell volume, which allows kinetic measurements with high sensitivity under batch or continuous flow conditions, the complete isolation of the cell from the UHV part during UHV measurements, continuous temperature control during both UHV and high-pressure operation, and rapid transfer between UHV and high-pressure stage. Gas dosing is performed by a designed gas-handling system, which allows operation as flow reactor with calibrated gas flows at adjustable pressures. To study the kinetics of reactions on the model catalysts, a quadrupole mass spectrometer is connected to the high-pressure cell. IR measurements are possible in situ by polarization-modulation infrared reflection-absorption spectroscopy, which also allows measurements at elevated pressures. The performance of the setup is demonstrated by test measurements on the kinetics for CO oxidation and the CO adsorption on a Au/TiO2/Ru(0001) model catalyst film at 1–50 mbar total pressure.
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07.35.+k, 07.30.Kf, 07.75.+h, 07.57.Ty

Production and characterization of micron-sized filaments of solid argon

Michael Grams, Boleslaw Stasicki, and J. Peter Toennies

Rev. Sci. Instrum. 76, 123904 (2005) (9 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (727 kB)

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A continuous 50-µm-diam filament of solid argon is produced in a moderate vacuum (4.2×10–3  mbar) by cooling argon gas to 70–90  K over the last 8  mm of a long fused silica capillary. Prior to formation of the straight filament the jet shows different stages characterized by spraying, snowballing, or spiraling filaments as documented by charge-coupled device (CCD) camera microscope pictures. Consecutive CCD pictures are used to measure the filament velocities, which increase with the driving gas pressure P0 up to about 4.0  cm/s at P0=400  bars with an intermediate peak at about 80  bars. This technique may find applications for producing wall-less cryogenic matrices, targets for laser plasma sources of extreme UV and soft-x-ray sources, plasma implosion experiments, or H2 pellets for injection into fusion reactors.
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07.20.Mc, 47.27.Wg

X-ray-absorption fine structure measurement with parallel-plate capacitor: Observation of surface electronic states of metals

Masashi Ishii and Aiko Nakao

Rev. Sci. Instrum. 76, 123905 (2005) (7 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (283 kB)

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For surface electronic state analyses of metals, we developed a new x-ray-absorption fine structure (XAFS) measurement technique with a parallel-plate capacitor. Since the capacitance is changed by x-ray-induced photoionization on the metal surface, the surface XAFS spectrum of a metal can be obtained from the capacitance dependent on the x-ray photon energy. We adopted this technique to the Cu metals. The XAFS spectrum at the Cu  K absorption edge is different from the conventional XAFS spectrum of either Cu or Cu2O. This finding suggests that the XAFS spectrum indicates two-dimensional (2D) electronic states between the Cu bulk and the Cu2O native oxide layer. The 2D electronic states were characterized by degeneration of Cu 4ppi and a blueshift of Cu 4psigma. These characteristics can be explained by hybridization of vertical Cu 4pz with horizontal 4px and 4py in CuO-like structure at the interface.
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07.85.Nc, 78.70.Dm, 73.20.At

A double-beam common path laser interferometer for the measurement of electric field-induced strains of piezoelectric thin films

Z. Huang and R. W. Whatmore

Rev. Sci. Instrum. 76, 123906 (2005) (4 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (236 kB)

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We report in this paper the development of a modified Mach-Zehnder-type double-beam common path laser interferometer for the measurement of electric field-induced strain in piezoelectric materials, especially for the thin films. Compared to previous interferometers, this one is simpler and more compact, and the measurement and reference arms share a common path for most of the optical length. Example results have been reported for the quartz, lead zirconate titanate (PZT) ceramic sample, and PZT thin films. Double- and single-beam measurements have been carried out at different frequencies for the same spot of a PZT thin-film sample and it was found that the single-beam values were a few times of the values as obtained from the double-beam technique. This phenomenon is confirmed by the laser scanning vibrometer measurements.
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07.60.Ly, 07.10.Pz, 77.84.Dy, 77.84.Bw, 77.65.Ly

Optical absorption spectrum measurement of films at a low temperature using photothermal bending spectroscopy

Hitoe Habuchi and Daisuke Harada

Rev. Sci. Instrum. 76, 123907 (2005) (4 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (107 kB)

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The optical absorption spectrum of a semiconductor film was obtained at a low temperature using an optical cantilever method called photothermal bending spectroscopy. The film, clamped on one side in a cryostat, was uniformly cooled with nitrogen gas. The product of the measurable optical absorption coefficient and the thickness of the film was better than 1×10–3 at 110  K. We demonstrated that the 1.74  eV peak in the optical absorption spectrum of a C60 film could not be observed at room temperature, but could be observed at 110  K due to a sharpening of the Urbach tail slope.
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78.66.Tr, 78.40.Ri, 78.20.Ci, 82.80.Kq
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CHEMISTRY

Design and characterization of late-mixing flash pyrolytic reactor molecular-beam source

Hahkjoon Kim, Kristin S. Dooley, Elizabeth R. Johnson, and Simon W. North

Rev. Sci. Instrum. 76, 124101 (2005) (3 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (99 kB)

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We report on the design and characterization of an intense pulsed beam source for the generation of expansion-cooled radical species. The source combines both dual pulsed valve late mixing for coexpansion of reactive gases with a pyrolytic end nozzle as a flash kinetic reactor. As a demonstration of the source we present evidence of BrO and ClO radical production and subsequent photodissociation studies of these species using velocity map ion imaging. The radicals are characterized by a rotational temperature of 150±40  K although substantially lower temperatures should be possible.
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07.77.Gx, 82.30.Lp, 82.50.-m, 82.30.Cf

Heated quartz microbalance to study thermally deposited calcareous scale

C. Gabrielli, H. Perrot, P. Rousseau, A. Belghazi, T. Chevrot, J. M. Colin, and C. Simonet

Rev. Sci. Instrum. 76, 124102 (2005) (9 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (966 kB)

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The scaling effect can affect drastically all equipment where water is used. In general, the phenomenon is amplified with hot fluids or hot pipes as, for example, conditions found in the heat exchangers. Thus, dramatic damages can occur that lead to dangerous economic consequences. The basic idea in this article is to promote the development of tools that can characterize the scaling power under certain conditions. A sophisticated heated quartz crystal microbalance was built and its performance was evaluated. It was shown that the scale must be deposited onto the sensor surface in an identic way compared with current scaling deposition conditions and the kinetics of deposition evaluated thanks to the microbalance response.
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07.10.Lw, 07.07.Df
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BIOLOGY AND MEDICINE

Instrumentation for video-rate near-infrared diffuse optical tomography

Daqing Piao, Hamid Dehghani, Shudong Jiang, Subhadra Srinivasan, and Brian W. Pogue

Rev. Sci. Instrum. 76, 124301 (2005) (13 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (1291 kB)

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This article describes the design, rationale, and system performance of a rapid imaging near-infrared diffuse optical tomography system that is capable of collecting tomographic measurements at video rate. Data-acquisition speed of 35  frames/s is achieved by spectral encoding of the sources, followed by spectral decoding of all detection channels in parallel in a spectrometer and using charge-coupled-device (CCD)-based detection. The combination of spectral decoding of the source lights horizontally in a spectrometer and spatial separation of the detector positions vertically at the entrance slit provides separate data for the entire set of source-detector pairs which can be acquired at the frame rate of the CCD camera. The described system features eight sources at an overall 785  nm center band with an average of 1.25  nm spacing in wavelength and eight detectors evenly deployed in a 27  mm array designed for imaging with small animal tissues. The system performs with localization error of 2.5  mm, and absorption recovering uncertainty of 16.7%. The point spread function of the imaging is estimated to be 4.1  mm when near to the edge and 10.4  mm at the center of the imaging array. Capture of transient changes of absorption coefficient in a dynamic phantom are also presented.
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87.63.Lk, 87.66.Xa
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GRAVITY; GEOPHYSICS; ASTRONOMY AND ASTROPHYSICS

Development of a simulator of a satellite-to-satellite interferometer for determination of the Earth's gravity field

Shigeo Nagano, Mizuhiko Hosokawa, Hiroo Kunimori, Taizoh Yoshino, Seiji Kawamura, Masashi Ohkawa, and Takashi Sato

Rev. Sci. Instrum. 76, 124501 (2005) (10 pages)

Online Publication Date: 14 December 2005

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A satellite-to-satellite laser interferometer is essential for a future gravity-field mission to improve the accuracy and spatial resolution of the Earth's gravity model. We have designed a ground-based simulator of a satellite-to-satellite interferometer, which aims to evaluate instrument error reflecting on the accuracy of the gravity-field retrieval and achieve the essential technologies required to measure the intersatellite range rate. The developed simulator was successfully operated with a range-rate sensitivity of 40  nm/s/sqrt(Hz) in the measurement band of 10–2–1  Hz. From a primary demonstration, it was confirmed to be available for experimental simulation of the satellite-to-satellite interferometer in the laboratory. The simulator will be a powerful tool for establishing guidelines for the development of future gravity missions.
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91.10.Pp
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ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Theoretical and experimental behavior of a compact magnetically insulated line oscillator electromagnetic structure

Richard Cousin, Jean Larour, Pierre Raymond, Joseph Wey, Philippe Gouard, and Alain Joseph Durand

Rev. Sci. Instrum. 76, 124701 (2005) (8 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (1213 kB)

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The magnetically insulated line oscillator (MILO) is a high power microwave source capable of delivering output powers greater than 1  GW at a frequency of several gigahertz. The device is a crossed electric and magnetic field oscillator without any external structure to establish the static magnetic field, required to guide the electron beam, thus making it compact. We report on a compact MILO device based on the U.S. Air-Force design where all dimensions are reduced by a factor of 2. All the key points are reviewed using the Electromagnetic-PIC (Particle-In-Cell) code MAGIC in two-dimensional geometry. The operating frequency of such a device is 2.44  GHz, leading to an output power slightly above 1  GW for an operating voltage of 500  kV and a maximum current of 45  kA. The output power can be increased up to 2  GW by optimizing the output coupling and reducing the beam loading effect. The analysis of the compact electromagnetic structure is based on the calculation of the external Q factor (Qext). The Qext coefficient is calculated for each resonant frequency of the four-cell coupled periodic resonator which accounts for the main part of the MILO slow wave structure. The optimized geometrical parameters such as the extractor vane radius (Rext=47  mm) and the collector length (Lcol=92  mm), which constitutes the output coupling section, lead to a maximum of simulated output power. A prototype has been built according to this geometry. The compact MILO structure is characterized by some cold tests (without electron beam) injecting a low rf power by a network analyzer; experimental results are presented and discussed in comparison with the simulation.
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84.30.Ng, 84.40.Dc, 85.70.-w, 41.20.-q, 02.40.-k

A cryogenic voltage amplifier with 36  MHz bandwidth using discrete GaAs metal-semiconductor field-effect transistors

B. H. Hu and C. H. Yang

Rev. Sci. Instrum. 76, 124702 (2005) (4 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (360 kB)

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We report a design procedure and performance of a voltage amplifier using commercially available GaAs metal-semiconductor field-effect transistors. There are two stages: a common-source amplifier that provides a moderate gain, followed by a common-drain stage for driving the 50  Omega coaxial cable. The overall voltage gain measured at 4.2  K with a 50  Omega load is 3.3, with a bandwidth of 36  MHz. The input-referred voltage noise is measured to be approximately 3.2  nV/[square root of]Hz in a wide frequency range.
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84.30.Le, 85.30.Tv

Design and performance of sliced-aperture corrugated feed horn antennas

J. Singal, E. Wollack, A. Kogut, M. Limon, P. Mirel, P. Lubin, and M. Seiffert

Rev. Sci. Instrum. 76, 124703 (2005) (4 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (108 kB)

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We report on the design of corrugated feed horn microwave antennas at 3.3, 5.6, 7.8, and 10.2 GHz for the absolute radiometer for cosmology, astrophysics, and diffuse emission experiment. These horns have low sidelobe symmetrical beams with 12° full width at half power, and three noteworthy features: a 30° slice at the aperture, a profiled rather than a linear taper, and a slowly varying groove depth along the length of the horn. The profiled taper and varying groove depth provided a narrow beam given the existing physical spatial constraints of the instrument in which the horns are used. The 30° slice was necessary for instrumental considerations and has a minimal effect on the symmetry of the beam. The slice reduces the effective aperture radius and overall length to that corresponding to an unsliced horn with an aperture at roughly the middle of the slice and does not introduce any undesirable effects.
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84.40.Ba, 07.57.Kp, 95.55.Jz
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THERMOMETRY; THERMAL DIFFUSIVITY; ACOUSTIC; PHOTOTHERMAL AND PHOTOACOUSTIC

Calibration of a thermocouple for measurement of oscillating temperature

Yusuke Tashiro, Tetushi Biwa, and Taichi Yazaki

Rev. Sci. Instrum. 76, 124901 (2005) (5 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (153 kB)

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We report on the dynamic calibration of a thermocouple for the measurement of the oscillating temperature. Temperature oscillation is induced in a gas-filled tube by a periodically forced pressure oscillation and measured by a thermocouple. The radial profile of the measured temperature oscillations is compared with the theoretical one, which is determined from the simultaneously measured pressure. A response function of the thermocouple is obtained from the difference in amplitude and phase angle between them by varying the diameter of the thermocouple, oscillating frequency, tube radius, and working gas. We can obtain a true temperature oscillation by using the response function given in this experiment.
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43.20.+g, 43.58.+z

1omega,  2omega, and 3omega methods for measurements of thermal properties

Chris Dames and Gang Chen

Rev. Sci. Instrum. 76, 124902 (2005) (14 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (227 kB)

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3omega methods are commonly used to measure the thermal conductivity of a substrate adjacent to a strip heater or the thermal conductivity and specific heat of a suspended wire. Here we consider the general case of a line heater that is also used to sense temperature. Analysis of all harmonics is presented in terms of generic thermal and electrical transfer functions and is readily adapted to other experimental configurations. We identify voltage signals at 2omega and 1omega that contain the same information about the thermal properties as the 3omega signal. The 2omega voltage requires a dc offset at the current source. The 1omega voltage requires a very stable current source, but eliminates the need for higher-harmonic detection, and is advantageous for studying the dynamics of systems with very fast thermal response times. The 1omega,  2omega, and 3omega methods compare favorably with experiments using a suspended platinum wire and a line heater on a Pyrex substrate. With a modern lock-in amplifier, no common-mode voltage subtraction is necessary, which simplifies the experiment compared to the common practice of balancing a bridge or using a multiplying digital-to-analog converter. We also show that the widespread practice of using a voltage source to approximate a current source is only valid when the sample resistance is small compared to the total electrical resistance of the circuit, and derive and experimentally verify a correction factor to be used otherwise.
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07.20.-n, 72.15.Eb

Automatic procedure for the correction of thermoelastic stress analysis data acquired in nonadiabatic conditions

A. Gallotti and A. Salerno

Rev. Sci. Instrum. 76, 124903 (2005) (7 pages)

Online Publication Date: 29 December 2005

Full Text: PDF (1673 kB)

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Thermoelastic stress analysis (TSA), performed on metallic components with a high diffusivity coefficient, seldom reaches adiabatic conditions. As a consequence, TSA results are affected by an attenuation whose entity varies locally, preventing the use of TSA as a reliable quantitative investigation means. The recovery of the adiabatic temperature and of the correct value of the first stress invariant, directly linked to it, can only be performed making an assumption on the local stress distribution. This article presents a method for automatically choosing, among a number of stress distribution functions, the one that performs the best correction of the raw TSA data. The implementation of this automatic correction procedure in a computer program allowed the point-by-point correction of whole TSA images.
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46.80.+j, 46.25.Hf
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GENERAL INSTRUMENTS

Characterization system for resonant micro- and nanocantilevers

Rasmus Sandberg, Anja Boisen, and Winnie Svendsen

Rev. Sci. Instrum. 76, 125101 (2005) (6 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (323 kB)

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We present a system for characterization of the resonant properties of micro- and nanocantilever sensors. The system has been constructed as a vacuum chamber with capabilities for controlling environmental conditions such as pressure, temperature, and chemical constituents. Characterization can be achieved either electrically or using a specialized laser-optical detection system. The system has been used to characterize the resonant properties of SiO2 cantilevers as well as other resonant structures. We present experimental results of a SiO2 resonant cantilever, showing an exceptional accuracy in resonant frequency determination, and demonstrating the importance of resonance characterization in a controlled environment.
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07.07.Df, 07.10.Cm, 07.30.Kf, 46.40.Ff

Microscopic four-point probe based on SU-8 cantilevers

S. Keller, S. Mouaziz, G. Boero, and J. Brugger

Rev. Sci. Instrum. 76, 125102 (2005) (4 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (335 kB)

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A microscopic four-point probe (µ4PP) for resistivity measurements on thin films was designed and fabricated using the negative photoresist SU-8 as base material. The device consists of four microscopic cantilevers, each of them supporting a probe tip at the extremity. The high flexibility of SU-8 ensures a stable electrical point contact between samples and probe tip with all four electrodes even on rough surfaces. With the presented surface micromachining process, µ4PPs with a probe-to-probe spacing of 10–20  µm were fabricated. Resistivity measurements on thin Au, Al, and Pt films were performed successfully. The measured sheet resistances differ by less than 5% from those obtained by a commercial macroscopic resistivity meter. Due to the low contact forces (Fcont<10–4  N), the µ4PP is suitable to be applied also to fragile materials such as conducting polymers. Here the authors demonstrate the possibility of performing resistivity measurements on 100-nm-thick pentacene (C22H14) films with a sheet resistance Rs>106  Omega/[square, open].
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84.37.+q, 07.10.Cm, 73.61.Ph, 73.61.At, 73.40.-c

Microfabricated continuous-flow, turbulent, microsecond mixer

Zigurts K. Majumdar, Jason D. B. Sutin, and Robert M. Clegg

Rev. Sci. Instrum. 76, 125103 (2005) (11 pages)

Online Publication Date: 21 December 2005

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We present a microfabricated, continuous-flow, turbulent mixing device that can mix two or more fluids to complete homogeneity on the molecular scale in the microsecond range. The current design is compact, portable, relatively simple to fabricate, adaptable for various measurement techniques, and consumes small sample volumes. The entire mixing process is observable and we use this feature to characterize the dependence of the progress of mixing on the flow velocity. We present details of the mixer's construction and optical data acquisition using fluorescence. Because the mixer is constructed using microfabrication technology, it is inexpensive and alterations are easy to explore. We show that the dependence of mixing times and pressure drop on the flow velocity agree well with theoretical expectations for turbulent pipe flow. This provides useful guidelines in predicting performance of this type of mixing device.
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85.85.+j

Pulsed laser heating and temperature determination in a diamond anvil cell

S. Deemyad, E. Sterer, C. Barthel, S. Rekhi, J. Tempere, and Isaac F. Silvera

Rev. Sci. Instrum. 76, 125104 (2005) (4 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (227 kB)

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Pulsed laser heating in a diamond anvil cell has several advantages over cw heating: it can suppress thermally activated diffusion of the pressurization medium into the gasket and diamond, suppress chemical reactions of impurities with the sample and environment, requires far less average power and thus less heating of the sample environment, and can attain very high temperatures. It was recently shown that it is possible to accurately measure the melting point of platinum and other materials at ambient conditions using a pulsed laser and a simple ungated CCD detector, measuring the time-averaged irradiance. We show that this same technique can be used for high-pressure samples in a diamond anvil cell. As a demonstration, the high-pressure melting curve of iron is reproduced and compared to literature values.
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42.62.Eh, 64.70.Dv, 07.20.Dt, 07.35.+k

Design of a bidirectional actuator for a nanopositioning system with a permanent magnet and an electromagnet

K. H. Kim and D. G. Gweon

Rev. Sci. Instrum. 76, 125105 (2005) (8 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (933 kB)

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A precision bidirectional linear actuator for ultraprecision systems is proposed and designed in this article. The actuator is composed of a symmetric structure with a force generation unit and a guide mechanism. The force generation part consists of a permanent magnet and an electromagnet, which generate a permanent and a reversible flux, respectively. The combination of permanent and reversible fluxes makes various flux densities in its air gaps between the moving part and the fixed yokes. The difference between flux densities in the lower and upper gaps creates forces for bidirectional linear motions of hundreds of micrometers. As a guide mechanism, two circular plates and one shaft are used. Reducing other forces generated by motions, except the z-directional motion, these circular plates in the form of a flexure endow the actuator with smooth motion, freedom from wear, and a high stiffness for a rapid settling time. The function of the shaft is to transfer motion to an object. Finally, the total body has a symmetric structure enabling it to be stable in terms of thermal error. The actuator is designed with the software tools MAXWELLTM2D and PRO-MECHANICATM. The designed actuator is evaluated with a linear current amplifier, a laser Doppler vibrometer for nanometer resolution, a dynamic signal analyzer for frequency responses of the proposed actuator, and a simple proportional-integral-derivative controller for its tracking performance.
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89.20.Kk, 85.70.-w, 46.70.De

Temperature-controlled autocollimator with ultrahigh angular measuring precision

Jie Yuan, Xingwu Long, and Kaiyong Yang

Rev. Sci. Instrum. 76, 125106 (2005) (6 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (316 kB)

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A temperature-controlled autocollimator with ultrahigh angular measuring precision is proposed in this article, which is different from our previous publication [J. Yuan and X. W. Long, Rev. Sci. Instrum. 74, 1362 (2003)]. The autocollimator consists of a zoom lens illuminating a charge-coupled device (CCD). This design provides a compact size and increased stability without compromising precision. Moreover, this design makes it possible to detect a target mirror with either plane reflectors or spherical reflectors. Devices for shock absorption and heat insulation were implemented to diminish external interferences. A special temperature-control system for the autocollimator is designed to control the temperature of the autocollimator. The temperature of the autocollimator fluctuates less than ±0.01  °C. The CCD camera's noise is a fatal obstacle that prevents us from achieving an ultrahigh angular measuring precision. In this article, the influence of the CCD camera's noise on the measuring resolution is analyzed theoretically in detail. Based on the analysis, some special noise-suppressing methods to eliminate the influence of the CCD camera's noise are proposed. Both the influence of the CCD camera's noise and the noise-suppressing methods have not been discussed in our previous publication [J. Yuan and X. W. Long, Rev. Sci. Instrum. 74, 1362 (2003)]. By using the methods mentioned above, the measuring precision of the autocollimator has been greatly improved and the requirements on the external condition have been greatly reduced. The method is proved to be reliable by a prototype experiment. Two-axis angular displacement can be measured simultaneously and a measuring precision of 0.005  arcsec has been achieved, which is currently the highest measuring precision in the world.
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42.79.Ag, 07.20.-n, 06.30.Bp, 42.15.Eq

Nanosecond rise time air-core current transformer for long-pulse current measurement in pulsed power

R. Shukla, A. Shyam, S. Chaturvedi, R. Kumar, D. Lathi, V. Chaudhary, R. Verma, K. Debnath, S. Sharma, J. Sonara, K. Shah, and B. Adhikary

Rev. Sci. Instrum. 76, 125107 (2005) (6 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (187 kB)

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A slow-wave delay line type air-core (nonmagnetic Nylon former) current transformer fabricated using silver epoxy for the measurement of currents of long pulse durations and few nanoseconds rise times is reported in this article. The advantage of using silver epoxy is that it fills all the voids between coil and shield and enhances the proximity of the coil to the shield, leading to a high value of distributed capacitance. Thus the transit time of the coil increases and it can measure fast current pulses of longer durations. Increasing the inductance of the coil can compensate for the resulting reduction in the sensitivity of the coil for matched termination. An easy experimental technique to find the value of the matched terminating resistor is also reported in this article. We have also done simulations of the slow wave current transformer using PSPICE.
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84.37.+q, 84.32.Hh, 84.30.-r

Machine vision for high-precision volume measurement applied to levitated containerless material processing

R. C. Bradshaw, D. P. Schmidt, J. R. Rogers, K. F. Kelton, and R. W. Hyers

Rev. Sci. Instrum. 76, 125108 (2005) (8 pages)

Online Publication Date: 29 December 2005

Full Text: PDF (799 kB)

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By combining the best practices in optical dilatometry with numerical methods, a high-speed and high-precision technique has been developed to measure the volume of levitated, containerlessly processed samples with subpixel resolution. Containerless processing provides the ability to study highly reactive materials without the possibility of contamination affecting thermophysical properties. Levitation is a common technique used to isolate a sample as it is being processed. Noncontact optical measurement of thermophysical properties is very important as traditional measuring methods cannot be used. Modern, digitally recorded images require advanced numerical routines to recover the subpixel locations of sample edges and, in turn, produce high-precision measurements.
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06.30.Bp

Resonant-cavity approach to noninvasive, pulse-to-pulse emittance measurement

J. S. Kim, C. D. Nantista, R. H. Miller, and A. W. Weidemann

Rev. Sci. Instrum. 76, 125109 (2005) (13 pages)

Online Publication Date: 29 December 2005

Full Text: PDF (948 kB)

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We present a resonant-cavity approach for noninvasive, pulse-to-pulse, beam emittance measurements of noncircular multibunch beams. In a resonant cavity, desired field components can be enhanced up to QLlambda/pi, where QLlambda is the loaded quality factor of the resonant mode lambda, when the cavity resonant mode matches the bunch frequency of a bunch-train beam pulse. In particular, a quad cavity, with its quadrupole mode (TM220 for rectangular cavities) at beam operating frequency, rotated 45° with respect to the beamline, extracts the beam quadrupole moment exclusively, utilizing the symmetry of the cavity and some simple networks to suppress common modes. Six successive beam quadrupole-moment measurements, performed at different betatron phases in a linear transport system, determine the beam emittance, i.e., the beam size and shape in the beam's phase space, if the beam current and position at these points are known. In the presence of x-y beam coupling, ten measurements are required. One measurement alone provides the rms beam size of a large aspect ratio beam. The resolution for such a measurement of rms beam size with the rectangular quad-cavity monitor presented in this article is estimated to be on the order of 10  µm. A prototype quad cavity was fabricated and preliminary beam tests were performed at the Next Linear Collider Test Accelerator at the Stanford Linear Accelerator Center. The results were mainly limited by beam jitter and uncertainty in the beam position measurement at the cavity location. This motivated the development of a position-emittance integrated monitor [J. S. Kim et al., Rev. Sci. Instrum. 76, 073302 (2005)].
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29.27.Fh, 29.27.Eg, 41.85.Ct, 29.17.+w
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NOTES

Closed, heated reaction chamber design for dynamic high-temperature x-ray-diffraction analyses of gas/solid displacement reactions

Michael S. Haluska, Robert L. Snyder, Kenneth H. Sandhage, and Scott T. Misture

Rev. Sci. Instrum. 76, 126101 (2005) (4 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (315 kB)

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A closed, x-ray transparent chamber for containing a hot reactive gas (generated from an internal condensed source) has been designed and evaluated for use in dynamic x-ray-diffraction analysis of a gas/solid displacement reaction. The chamber consisted of a square-bottom base and lid machined from dense pyrolytic graphite. The base contained a flat pedestal, upon which SiO2 microshells (the reactant oxide) were placed, raised above adjacent cavities holding Mg flakes (the condensed precursor to the reactive gas). Upon heating to 650 °C, the Mg evaporated and reacted with the SiO2 inside the sealed chamber. By passing incident and diffracted x rays through the vertical side walls of the chamber and by blocking undesired graphite-diffracted x rays with platinum, the Mg(g)/SiO2(s) displacement reaction could be tracked with time. This is the first use of dynamic high-temperature x-ray diffraction analysis to monitor the progress of a displacement reaction involving a reactant gas that was generated and confined within a closed reaction chamber.
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82.40.-g, 82.30.Hk, 82.20.-w, 82.80.Ej

Debris characteristics of a laser-produced tin plasma for extreme ultraviolet source

Takeshi Higashiguchi, Chirag Rajyaguru, Naoto Dojyo, Yosuke Taniguchi, Koji Sakita, Shoichi Kubodera, and Wataru Sasaki

Rev. Sci. Instrum. 76, 126102 (2005) (3 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (197 kB)

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We measured debris characteristics of a tin (Sn) plasma produced by a 10-ns infrared Nd:YAG laser. A maximum kinetic energy of 7  keV of tin ions was observed. Such suprathermal tin ions emitted from a solid planar target consisted of singly and doubly ionized tin ions. Both suprathermal ions and neutral fragments emitted from a target showed the angular distributions of cos4  theta which were narrower than the 13.5-nm extreme ultraviolet (EUV) emission distribution of cos0.5  theta. These measurements would give important information on debris mitigation for efficient EUV sources in the next generation lithography.
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52.70.Nc, 52.38.Mf, 52.50.Jm, 52.25.Os

Self-oscillating rubidium magnetometer using nonlinear magneto-optical rotation

P. D. D. Schwindt, L. Hollberg, and J. Kitching

Rev. Sci. Instrum. 76, 126103 (2005) (4 pages)

Online Publication Date: 14 December 2005

Full Text: PDF (180 kB)

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The detection of nonlinear magneto-optical rotation (NMOR) of polarized light through alkali atomic vapor is a highly sensitive technique for measuring magnetic fields. We demonstrate that when using frequency modulated light to excite the NMOR resonance, it is possible to cause the system to self-oscillate. The NMOR signal is not a simple replica of the sine wave modulation of the light, but rather contains many higher harmonics of the modulation frequency, and we implement two ways of processing the signal to recover the fundamental modulation frequency in the feedback loop and induce self-oscillation. Self-oscillation simplifies and reduces the power consumption of the electronics required to operate a magnetometer, making the NMOR technique attractive for commercialized magnetic sensors.
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07.55.Ge, 85.70.Sq

73-W-long pulse kinetically enhanced copper vapor laser using wide aperture discharge tube

B. Singh, V. V. Subramaniam, S. R. Daultabad, and A. Chakraborty

Rev. Sci. Instrum. 76, 126104 (2005) (3 pages)

Online Publication Date: 21 December 2005

Full Text: PDF (61 kB)

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A wide aperture kinetically enhanced copper vapor laser consisting of a ~47  mm bore and 1450  mm length discharge tube is demonstrated with moderate input power of ~5  kW, and overall efficiency of ~1.45%. The laser pulse durations were observed to be ~60  ns full width at half maximum. An increase in output power from 17  to  73  W at ~9.4  kHz (a factor of ~4.3) has been achieved due to kinetic enhancement effects in this laser. Output laser pulse shape monitoring was used for optimization of maximum output power from the laser.
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42.55.Lt, 42.60.By, 42.65.Re, 42.60.Fc

On unique parameters and unified formal form of hot-wire anemometric sensor model

P. Ligeza

Rev. Sci. Instrum. 76, 126105 (2005) (3 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (55 kB)

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This note reviews the extensively adopted equations used as models of hot-wire anemometric sensors. An unified formal form of the mathematical model of a hot-wire anemometric sensor with otherwise defined parameters is proposed. Those parameters, static and dynamic, have simple physical interpretation and can be easily determined. They show directly the range of sensor application. They determine the metrological properties of the given sensor in the actual medium. Hence, the parameters' values might be ascribed to each sensor in the given medium and be quoted in manufacturers' catalogues, supplementing the sensor specifications. Because of their simple physical interpretation, those parameters allow the direct comparison of the fundamental metrological properties of various sensors and selection of the optimal sensor for the given research measurement application. The parameters are also useful in modeling complex hot-wire systems.
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06.30.Gv, 01.30.Rr

Polarizance of a synthetic mica crystal polarizer and the degree of linear polarization of an undulator beamline at 880  eV evaluated by the rotating-analyzer method

Takashi Imazono, Toko Hirono, Hiroaki Kimura, Yuji Saitoh, Masahiko Ishino, Yasuji Muramatsu, Masato Koike, and Kazuo Sano

Rev. Sci. Instrum. 76, 126106 (2005) (4 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (109 kB)

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The polarization performance of a reflection-type polarizer made with a synthetic mica (fluorophlogopite) single crystal (002) in symmetric Bragg geometry was evaluated at the photon energy of 880  eV by means of the rotating-analyzer method. An experiment was performed at the undulator beamline at the SPring-8. The reflectance in the s-polarization configuration was 2.6% at an incidence angle of around 45°. As the result of the analysis based on the rotating-analyzer method, the polarizance of the polarizer and the degree of linear polarization of the incident light at 880  eV were found to be 0.997±0.002 and 0.993±0.004, respectively.
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41.50.+h, 42.25.Ja, 42.79.Ci

350 mW high-power He–Ne laser and its application in photodynamic therapy

Yi-Ming Ling and Si-En Wu

Rev. Sci. Instrum. 76, 126107 (2005) (3 pages)

Online Publication Date: 27 December 2005

Full Text: PDF (218 kB)

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A high-power He–Ne laser that has two laser tubes with a flat discharge cross section is designed and made. It can generate the total output power of more than 350 mW. The laser beams can be coupled into a quartz optic fiber using an optical system and the output power from the end of the optic fiber is more than 280 mW. The optic fiber will then pass through the endoscope tube to enter the human body to destroy the cancer for photodynamic therapy (PDT). In 44 clinical cases where the high He–Ne laser is used for PDT, the complete response rate is about 60%. The design of this high-power He–Ne laser and its application are introduced briefly in this article.
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87.54.Fj, 87.63.Lk, 42.62.Be, 42.55.Lt, 42.60.By, 42.81.Pa

Modification of photoionization mass spectrometer with synchrotron radiation as ionization source

Chaoqun Huang, Bin Yang, Rui Yang, Jing Wang, Lixia Wei, Xiaobin Shan, Liusi Sheng, Yunwu Zhang, and Fei Qi

Rev. Sci. Instrum. 76, 126108 (2005) (4 pages)

Online Publication Date: 27 December 2005

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In this article we introduce a modification on ion optics of a reflectron time-of-flight mass spectrometer for the study of flame chemistry with synchrotron radiation as a continuous ionization source. A small bias voltage is used in the extraction region to simultaneously reduce the background ion signal, eliminate secondary ionization process caused by photoelectrons, increase the ion detection efficiency, and improve the mass resolution.
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07.75.+h, 41.85.-p

Development of liquid-metal-ion source low-energy ion gun/high-temperature ultrahigh vacuum scanning tunneling microscope combined system

M. Uchigasaki, T. Kamioka, T. Hirata, T. Shimizu, F. Lin, T. Shinada, and I. Ohdomari

Rev. Sci. Instrum. 76, 126109 (2005) (4 pages)

Online Publication Date: 27 December 2005

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A liquid-metal-ion source low-energy ion gun/high-temperature ultrahigh vacuum scanning tunneling microscope combined system (LMIS-IG/STM) has been developed in order to investigate the ion beam modification process in situ based on our previous ion gun/STM combined system (IG/STM). Various kinds of metal ions can be irradiated with low acceleration energy of 0.01–5  keV during STM observation at 400–600  °C. As an example, real-time STM observation of Si(111)7×7 surface irradiated with Si2+ ions is demonstrated. The STM results have shown that the surface defects generated by Si2+ ion irradiation exhibit similar behavior of surface defects induced by Ar+ irradiation with IG/STM.
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07.77.Ka, 07.79.Cz, 07.30.Kf, 07.20.Ka, 61.80.Jh

Frequency-modulation atomic force microscopy at high cantilever resonance frequencies using the heterodyne optical beam deflection method

Takeshi Fukuma, Kenjiro Kimura, Kei Kobayashi, Kazumi Matsushige, and Hirofumi Yamada

Rev. Sci. Instrum. 76, 126110 (2005) (3 pages)

Online Publication Date: 27 December 2005

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We have developed a frequency-modulation atomic force microscope (FM-AFM) with a wideband cantilever deflection sensor using the heterodyne optical beam deflection method. The method enhances the bandwidth of the deflection measurement up to the maximum frequency for the laser power modulation, which can be as high as gigahertz order. The phase and frequency of the cantilever vibration at 5.24  MHz are detected with a deflection noise density of 100  fm/sqrt(Hz). FM-AFM imaging is performed on a Au(111) surface with a high-frequency cantilever.
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07.79.Lh, 68.37.Ps, 61.41.+e

Meteorological radiosonde interface for atmospheric ion production rate measurements

R. G. Harrison

Rev. Sci. Instrum. 76, 126111 (2005) (4 pages)

Online Publication Date: 27 December 2005

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A disposable balloon-carried instrument, interfaced to a commercial meteorological radiosonde for measuring the atmospheric ion production rate, is described. The sensor used is a gamma-sensitive Geiger tube, operated at 550  V bias, produced from a lightweight transformerless supply. The supply requires 15  V  at  10  mA, and precision regulation is used to minimize the Geiger tube's response to bias voltage changes. The supply was stable to 0.1% for supply voltage variations between 15 and 25  V, and varied by less than 1% over temperatures from –53  to  25  °C during an atmospheric ascent. A digital counter incremented with each Geiger tube event, and the instantaneous count value was telemetered over a radiolink, time-stamped on reception to obtain the count rate. The derived ion production rate profile agrees with a standard parametrization to 5%.
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93.85.+q
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ERRATA

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Erratum: "Reflectron velocity map ion imaging" [Rev. Sci. Instrum. 76, 104101 (2005)]

Brian D. Leskiw, Myung Hwa Kim, Gregory E. Hall, and Arthur G. Suits

Rev. Sci. Instrum. 76, 129901 (2005) (1 page)

Online Publication Date: 14 December 2005

Full Text: PDF (37 kB)

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 Abstract Unavailable
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32.10.Bi, 82.80.Rt, 99.10.Cd

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