Am. Lindenberg et al., Time-resolved X-ray diffraction from coherent phonons during a laser-induced phase transition, PHYS REV L, 84(1), 2000, pp. 111-114
Time-resolved x-ray diffraction with picosecond temporal resolution is used
to observe scattering from impulsively generated coherent acoustic phonons
in laser-excited InSb crystals. The observed frequencies and damping rates
are in agreement with a model based on dynamical diffraction theory couple
d to analytic solutions for the laser-induced strain profile. The results a
re consistent with a 12 ps thermal electron-acoustic phonon coupling time t
ogether with an instantaneous component from the deformation-potential inte
raction. Above a critical laser fluence, we show that the first step in the
transition to a disordered state is the excitation of large amplitude, coh
erent atomic motion.