The diffusion of silver and gold tracers in silver-gold in crystals of 0, 8, 17, 35, 50, 66, 83, 94 and 100 at. % gold has been measured. It is shown that the limiting error in such measurements is due to temperature uncertainty rather than to the sectioning process. The activation energies obtained do not vary in proportion to the melting point or heat of fusion, and the deviations cannot be rectified in terms of lattice parameter arguments. The activation energies in the pure metals are better accounted for by the theory of Turnbull and Hoffman than by that of Swalin. The suggestion that the vacancy migration energy should vary as (cu -Cn) is not confirmed. From the change in frequency factor with composition it is deduced that the activation entropy of migration of a vacancy decreases linearly with composition by 1.5R from pure silver to pure gold. The dependence of diffusion coefficient on gold content is compared with the theories of Hoffman, Turnbull, and Hart, of Reiss, of Manning, and of Lidiard, and impurity correlation factors of reasonable magnitudes are obtained. Particularly difficult to treat, however, is the decrease in diffusion coefficients resulting from additions of the rapid diffuser silver to the slow diffuser gold. An experiment to measure the effects of vacancy flux directly is proposed.

The effect of plastic deformation on the optical absorption, ESR, and thermoluminescent properties of MgO has been investigated. Plastic deformation produces an optical absorption band a t about 217 nm whose intensity is proportional to the percent of deformation.No new ESR signals were detected in the deformed crystals. When deformed crystals are irradiated with 6oCo y-rays, however, the ESR signal from the F-center is observed and several new optical absorption bands also appear. Impurity ion ESR signals in y-irradiated samples have been compared with thermoluminescence spectra. The results indicate that the blue thermoluminescence a t 3.3 eV and 85 "C is due to Fez+ converting to Fe3+ and the red thermoluminescence a t 1.7 eV and 85 "C is due to the formation of Cr3+.Es wird der EinfluS einer plastischen Verformung auf die optische Absorption, ESR und thermische Lumineszenz von MgO untersucht. Die plastische Deformation erzeugt optische Absorption bei 217 nm, deren StLrke direkt proportional zur Verformung ist. I n den verformten Kristallen wurden keine neuen ESR-Signale gefunden. Jedoch wurden ESR-Signale von F-Zentren und verschiedene neue optische Bander beobachtet, wenn die deformierten Kristalle y-bestrahlt wurden. Die ESR-Signale von Fremdionen in den y-bestrahlten Proben wurden mit den thermischen Lumineszenzspektren verglichen. Die Ergebnisse weisen darauf hin, da8 die blaue Lumineszenz bei 3,3 eV und 85 "C beim Ubergang von Fez+ in Fe3+ nnd die rote bei 1,7 eV und 85 "C bei der Bildung von Cr3+ entsteht.

We report on the investigation of free-carrier absorption characteristics for epitaxially grown p-type silicon thin films in the far-infrared region ͑50-200 m͒, where Si homojunction interfacial workfunction internal photoemission ͑HIWIP͒ detectors are employed. Five Si thin films were grown by molecular beam epitaxy on different silicon substrates over a range of carrier concentrations, and the experimental absorption data were compared with calculated results. The free-hole absorption is found to be almost independent of the measured wavelength. A linear regression relationship between the absorption coefficient and the carrier concentration, in agreement with theory, has been obtained and employed to calculate the photon absorption probability in HIWIP detectors.

Using solution samples, the absolute infrared absorption intensities of five fundamental bands of CH2Cl2 were measured by an extrapolation technique and by approximate methods suggested by Ramsay. These determinations were used to test a classical relationship, proposed by Polo and Wilson, between corresponding liquid and vapor absorption band intensities. Qualitative agreement with published vapor intensity measurements was obtained.