TRANSPORT OF PHONONS INTO DIFFUSIVE MEDIA

Earlier results had indicated, under some conditions, a discrepancy between the observed spectral distribution of phonons produced by the heat-pulse method and the distribution predicted by the acoustic-mismatch model. Through additional measurements of the film temperature we show that the discrepancy can be resolved in terms of diffusive scattering at foreign and isotopic impurities in the bulk of the substrate. © 1979 The American Physical Society.