title: Time-resolved X-Ray diffraction from coherent phonons during a laser-induced phase transition
abstract: 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 coupled to analytic solutions for the laser-induced strain profile. The results are consistent with a 12 ps thermal electron-acoustic phonon coupling time together with an instantaneous component from the deformation-potential interaction. Above a critical laser fluence, we show that the first step in the transition to a disordered state is the excitation of large amplitude, coherent atomic motion.
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720, USA.
authors.initials: AM
authors.lastname: Lindenberg
authors.initials: I
authors.lastname: Kang
authors.initials: SL
authors.lastname: Johnson
authors.initials: T
authors.lastname: Missalla
authors.initials: PA
authors.lastname: Heimann
authors.initials: Z
authors.lastname: Chang
authors.initials: J
authors.lastname: Larsson
authors.initials: PH
authors.lastname: Bucksbaum
authors.initials: HC
authors.lastname: Kapteyn
authors.initials: HA
authors.lastname: Padmore
authors.initials: RW
authors.lastname: Lee
authors.initials: JS
authors.lastname: Wark
authors.initials: RW
authors.lastname: Falcone