An ultrasonic cw resonance technique for the measurement of the velocity of sound in solids is described. The end correction due to the presence of the transducer and coupling film can be calculated from consideration of a transmission-line equivalent circuit. An experimental comparison is made of th~ cw ~nd two pulse techniques over the frequency range 5 to 45 Mc. Application of the cw :esonance techmque IS made to the measurement of the room-temperature adiabatic elastic constants of smgle crystals of RbBr, RbI, CsBr, and Csl. A tabulation of the important elastic properties of these crystals is presented.
Measurements were made of the rate of buildup of an electrical discharge in argon in the pressure range from 5 to 60 cm Hg. The results are interpreted on the basis of a secondary mechanism due to delayed photons. The photon delay times which fit the observed data are in the neighborhood of five microseconds over the range of pressures investigated. These photon delay times are compared with (a) calculated imprisonment times for resonance radiation, and (b) delay times for molecular radiation as observed by Colli. Considering the uncertainty in the calculations and the lack of knowledge about the energy distribution between the two main resonance lines, the imprisonment times are of the right magnitude to explain the observed buildup rates. The Colli-process delay times are in fair agreement with the data at the higher pressures; at the low pressures they are definitely too slow to explain the observed buildup rates.
The ultrasonic cw resonance technique was used to measure the adiabatic elastic constants of single-crystal aluminum antimonide at 27°C. The values for the elastic stiffness constants, in units of 1011 d/cm2, are: c11 = 8.939, c12 = 4.427, and c44 = 4.155. A theoretical density of 4.36 g/cc was used. The values of c11 and c44 for single crystal GaSb obtained by the cw resonance technique are compared with previous values obtained by pulse-echo techniques.
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