Volume 15, Issue 5, 01 September 1969
Index of content:
15(1969); http://dx.doi.org/10.1063/1.1652935View Description Hide Description
Photoluminescence has been observed from oxygen (O16) ions implanted into ZnTe. Doses of 5 × 1013 oxygen ions/cm2 were implanted at room temperature with energies between 50 and 250 keV. After annealing at 300–400°C in zinc vapor, the characteristicphotoluminescence spectrum from the oxygen isoelectronic trap was observed. Care was taken to ensure that the spectrum was a direct result of the implanted oxygen by studying unimplanted and neon‐implanted samples. The anticipated isotope shift was observed in the spectrum for samples implanted with O18.
15(1969); http://dx.doi.org/10.1063/1.1652936View Description Hide Description
The operation of an optical parametric oscillator which is directly pumped by the 1.06‐μ output of a continuously pumped, repetitively Q‐switched Nd:YAG laser is described. The oscillator uses a 3‐mm lithium niobate crystal in a non−90° orientation as the nonlinear material. 17 mW of average output power at 2 μ have been obtained giving an oscillator conversion efficiency of 8%. Measurements are also reported of pump power threshold, pump depletion, and wavelength tuning of the oscillator. No optically induced index inhomogeneities were observed in the lithium niobate.
15(1969); http://dx.doi.org/10.1063/1.1652937View Description Hide Description
A high‐efficiency, high‐resolution, high‐dispersion, low‐cost x‐ray spectrometer is described. Although the instrument was developed primarily for space‐science applications, it has a broad range of application for normal laboratory research problems. As an example of its performance, measurements of the CrKα1,2 spectrum are presented. The observed, uncorrected full‐widths at half‐maximum intensity are Kα1 = 2.09 eV and Kα2 = 2.67 eV. Fine structure details, hitherto unreported, were also observed.
15(1969); http://dx.doi.org/10.1063/1.1652938View Description Hide Description
A cw visible ring‐cavity parametric oscillator has been constructed and pump depletions of 60% have been observed. The experiment verified the increased conversion efficiency predicted for a parametric oscillator operating without a back‐generated pump wave, and also showed the improved stability which can result from the optical isolation provided by the ring‐cavity configuration.
15(1969); http://dx.doi.org/10.1063/1.1652939View Description Hide Description
15(1969); http://dx.doi.org/10.1063/1.1652940View Description Hide Description
The Auger spectrum of the cleaved (111) Si surface shows the same transitions as that of an annealedsurface having a Si(111)7 structure. This result indicates that the previously observed transitions in the Auger spectrum of Si(111)7 surfaces are all due to Si and that there is no evidence that the Si(111)7 structure is impurity stabilized.
15(1969); http://dx.doi.org/10.1063/1.1652942View Description Hide Description
The electroreflectance of anodic oxide films, at wavelengths longer than the absorption edge, has been proposed to result from an electro‐optic modulation of the refractive index. It is shown here that it is also possible to attribute the observed behavior to a modulation of the oxide film thickness by the electrostatic attraction of the electrodes.
15(1969); http://dx.doi.org/10.1063/1.1652943View Description Hide Description
Thermal emission rates of electrons and holes at the gold‐acceptor center (EC − E Au− = 550 mV) and of holes at the gold‐donor center (E Au+ − EV = 350 mV) are measured using the dark current, dark capacitance, and photocapacitance transient methods. About ten decades of the electron emission rate and eight decades of the hole emission rates are obtained in the temperature range of −160 to +100°C. The data correspond to electric fields of 104 and 105 V/cm maximum field in the p‐n junction and differ from the thermal equilibrium emission rates computed from previously published capture rate data at thermal equilibrium due to the field dependence of the capture rate from hot electron effect and of the emission rate from barrier lowering of the impurity potential.
15(1969); http://dx.doi.org/10.1063/1.1652944View Description Hide Description
A self‐consistent analysis of pulse propagation inside a laser cavity containing, in addition to an amplifying medium, some material displaying the optical Kerr effect, yields ultrashort pulses. These pulses become stable in the limit of high line‐center excess gain with the stabilization provided by an interplay between strong chirping in the Kerr medium and bandlimiting in the laser medium.
15(1969); http://dx.doi.org/10.1063/1.1652945View Description Hide Description
Electrical conduction in thin (400−1500 Å) single‐crystal aluminumfilms vacuum evaporated on NaCl substrates is explained by a simple model and verified by experimental results. The resistivity of the inter‐island boundaries is accounted for by considering the filmstructure as a metal—insulator matrix and calculating its equivalent resistivity. An unambiguous comparison can then be made with the Fuchs—Sondheimer theory of size‐affected conduction in thin metal films only after subtracting off the resistivity contribution due to interisland boundaries.
15(1969); http://dx.doi.org/10.1063/1.1652946View Description Hide Description
Surfaceelastic waves have been generated at 60 MHz by magnetostrictive coupling in yttriumirongarnet (YIG). The transducers were evaporated aluminum meander lines. For a YIG plate with the (110) axis normal to the free surface and propagation along the (001) axis, maximum coupling occurred for the static field parallel to the direction of propagation. The effect of the internal magnetic field gradient on the transducer efficiency and the signal delay is discussed.