SURFACE PHONON SPECTROSCOPY WITH FREQUENCY-DOMAIN IMPULSIVE STIMULATED LIGHT-SCATTERING

Coherent surface acoustic phonons are excited thermoelastically by two picosecond laser pulses and detected via diffraction of a quasi-cw pr obe beam, whose spectrum is analyzed with a scanning Fabry-Perot inter ferometer. Using laser-generated rather than thermal phonons leads to orders of magnitude increase in the signal compared to conventional su rface Brillouin spectroscopy, resulting in acquisition times under one minute with a simple spectral apparatus. Measurement of surface acous tic mode velocities on a thin gold film on fused silica in the frequen cy range 100 MHz - 2 GHz is demonstrated. Copyright (C) 1996 Published by Elsevier Science Ltd