Volume 17, Issue 8, 15 October 1970
Index of content:
17(1970); http://dx.doi.org/10.1063/1.1653414View Description Hide Description
Reflection and transmission secondary emission ratios have been measured for a thin Si sample with one surface activated to a state of negative electron affinity. Reflection‐mode gains of 950 were observed at 20‐keV primary energy. The highest transmission secondary emission ratio was 725 at 20‐keV primary energy. The high secondary emission gains result from the effective negative electron affinity at the surface of the sample together with a long escape depth for internal secondaries.
17(1970); http://dx.doi.org/10.1063/1.1653415View Description Hide Description
Na, Li, and Ne have been implanted into CdS in order both to study the luminescence and to attempt to achieve type conversion. Acceptor luminescence, due to the alkali impurities, has been produced with significant intensity, but type conversion has not been observed. The luminescence efficiency and the induced emission intensity as a function of annealing temperature have been obtained.
17(1970); http://dx.doi.org/10.1063/1.1653416View Description Hide Description
The proton spin‐lattice relaxation timeT 1 of p‐methoxybenzilidene‐p′‐cyanoanaline has been studied as a function of molecular alignment in a dcelectric field. The experimental results clearly show a large anisotropy in T 1 for the benzene‐ring protons as well as an isotropic spin‐lattice relaxation time associated with the remaining protons. These results are in agreement with the most recent theoretical descriptions.
17(1970); http://dx.doi.org/10.1063/1.1653418View Description Hide Description
Measurements of electrical conductivity as a function of electric field were used to obtain electron‐energy relaxation times τε in n‐InSb with 1014 carriers/cm3 in the temperature range from 5 to 34 K. Comparison of results with theoretical predictions demonstrated that the usual mechanisms involving single‐phonon interactions cannot adequately describe τε, especially in the range between 12 and 34 K. The data are highly suggestive of a two‐phonon process involving the emission of a 0.0223‐eV transverse optical phonon and absorption of a 0.0054‐eV transverse acoustic phonon.
17(1970); http://dx.doi.org/10.1063/1.1653419View Description Hide Description
The effects of implantation of argon on the optical properties of GaP films and bulk have been investigated for doses of 1013 to 1015/cm2 and energies between 1.5 and 3 MeV. Implantation of ordered films and bulk GaP results in a marked change in the optical absorption edge from about 2.3 eV to less than 1.0 eV, similar to behavior observed for amorphous films and for those subject to neutron irradiation. A maximum value of 3.22 has been observed for the index of refraction of implanted films as compared with 3.06 for bulk or highly ordered films. Bulk optical behavior can be recovered for implantedGaP with annealing at temperatures below 600°C.
17(1970); http://dx.doi.org/10.1063/1.1653420View Description Hide Description
A rotating dynamic capacitor is used to measure the contact potential difference between a gold reference electrode and λ goldfilm during the nucleation of a silver overlayer. An interpretation of the resulting graphs is given and the curves are fitted to an exponential relationship between the mean overlayer thickness and the percentage area covered. These results are compared with results for a gold overlayer on silverfilm.
17(1970); http://dx.doi.org/10.1063/1.1653421View Description Hide Description
Techniques have been developed using argon ion milling to produce high‐density microstructure arrays of permalloy magnetic dipoles for use in magnetic bubbledevices. Ion milling is used to replace the chemical etch process in the usual photolithographic method, which results in an order‐of‐magnitude improvement in density. A 1000‐bit I and bar shift register has been made in which the spacing between elements in 7.5μ, and the width of the elements are ∼ 1μ. The entire structure is 0.25 mm (or 10 mil) square.
17(1970); http://dx.doi.org/10.1063/1.1653422View Description Hide Description
Backscattering of MeV 4He ions has been used to analyze the Ga and As content in SiO2 and Si3N4dielectric layers deposited on single‐crystal GaAs substrates. Changes in impurity concentrations and distributions are seen after isothermal annealing at both 750 and 800°C. Evidence for Ga outdiffusion is clear.
17(1970); http://dx.doi.org/10.1063/1.1653423View Description Hide Description
A model of a dye laser electronically tuned by an acousto‐optic filter is analyzed.Chirping modes are superposed to yield a steady‐state periodic solution which predicts a shift of the spectrum to the high end of the filter band and appreciable spectral narrowing. For the example considered, the theory predicts a narrowing factor of 100.
17(1970); http://dx.doi.org/10.1063/1.1653424View Description Hide Description
An investigation has been made on variations in radiation‐induced conductivity of two different types of CdS single crystals near liquid‐nitrogen temperature during 5‐MeV electron irradiation. The conductivity of a high‐conductivity crystal is decreased and that of a low‐conductivity crystal is increased with irradiation. Both conductivities come nearer to each other and seem to approach a limiting value as irradiation is continued. Two possible interpretations for the experimental result are also presented.
17(1970); http://dx.doi.org/10.1063/1.1653425View Description Hide Description
It is found that (1) the current‐voltage relation of graphite has three kink points under the influence of a transverse of a transverse magnetic field, and (2) the kink effect is observed even at such a high temperature as 300°K. These kinks are attributed to the interaction between conduction electrons and various modes of phonons that are unique in the lamellar structure material.
17(1970); http://dx.doi.org/10.1063/1.1653426View Description Hide Description
The pulse shape of a mode‐locked continuously pumped Nd:YAG laser has been studied using an optical correlation technique. The shape is found to be Gaussian under stable conditions with the phase‐modulator frequency tuned to the cavity‐mode difference frequency. This result is consistent with the theory of mode locking in lasers with homogeneous broadening.
17(1970); http://dx.doi.org/10.1063/1.1653427View Description Hide Description
When a high‐energy electron traverses a thin dielectric film guiding a laser beam, it is partially scattered by the electromagnetic field. The scatteredwave function and the probability amplitude then carry optical information as time and spatial modulation. This effect, rather than classical bunching of electrons, is proposed as the modulation mechanism in the Schwarz‐Hora experiment.
17(1970); http://dx.doi.org/10.1063/1.1653428View Description Hide Description
The dependence of the intensity of the reemitted radiation in the Schwarz‐Hora effect as a function of electron beam intensity, coherence time, energy spread, and beam length is calculated. Sufficient information is given to provide for experimental confirmation or rejection of the hypothesis that radiation occurs by virtual excitation of and longitudinal dipole radiation from target ions. Two terms, one quadratic and one linear in the beam current, are found.
17(1970); http://dx.doi.org/10.1063/1.1653429View Description Hide Description
A large increase of ferromagnetic Curie temperature from 69.5 to ∼180°K has been discovered in EuO films by Fe doping. In films containing Fe up to 8% by weight, the structure is essentially the same as bulk EuO, the magnetic moment (at 4.2°K) is reduced slightly to 190 emu/g, the longitudinal Faraday rotation shows a similar wavelength dependence as that of pure EuO with a maximum positive rotation of 2.4×105 deg/cm at 6500 Å at an incidence angle of 65°, square hysteresis loops extend to ∼160°K, and the optical absorption characteristics are modified by Fedoping with a peak absorption coefficient of 2.4×105/cm (at 300°K) at 5800 Å.
17(1970); http://dx.doi.org/10.1063/1.1653430View Description Hide Description
The technique of inverted Lamb‐dip spectroscopy was used to observe 43 SF6absorption lines coincident with the P(18) line and 24 lines coincident the P(16) line in the 10.6‐μ band of the CO2 laser. Using heterodyne methods, line spacings on the order of 1 MHz were measured, and the resulting line spectra were referenced to laser line center.