Browsing by Author "Thiessen, Nicholas Paul"
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Item The effect of electron-phonon interactions on the velocity of sound in bismuth(1968) Thiessen, Nicholas Paul; Rich, D. C.; Staas, G. M.; Kern, John W.; Kouri, Donald J.There is a strong interaction between the electrons in a solid and an acoustic wave when the electrons have a component of velocity in the direction of sound propagation which is equal to the velocity of sound in the material. A calculation is done to estimate the magnitude of the effect this interaction will have on the velocity of sound. An analysis of the experimental techniques adequate to detect this effect is given, and a detailed, description and evaluation of the experimental apparatus necessary is presented.Item The velocity of sound in bismuth under conditions of ultrasonic amplification(1973) Thiessen, Nicholas Paul; Coon, Julian, B.; Waller, R. H.; Haas, Gregory M.; Finch, Robert D.; Kern, John W.A simple calculation is presented which generates the dependence of the attenuation coefficient and sound velocity on the conductivity. Resistivity, attenuation, and sound velocity measurements are presented and compared with the theoretical expressions where practicable. Agreement between theory and experiment is shown to be qualitatively very poor, but the magnitudes of the attenuation and velocity changes are roughly as expected.