title: Anharmonic lattice dynamics in germanium measured with ultrafast x-ray diffraction.
abstract: Damping of impulsively generated coherent acoustic oscillations in a femtosecond laser-heated thin germanium film is measured as a function of fluence by means of ultrafast x-ray diffraction. By simultaneously measuring picosecond strain dynamics in the film and in the unexcited silicon substrate, we separate anharmonic damping from acoustic transmission through the buried interface. The measured damping rate and its dependence on the calculated temperature of the thermal bath is consistent with estimated four-body, elastic dephasing times (T2) for 7-GHz longitudinal acoustic phonons in germanium.
authors.affiliation: Department of Chemistry and Biochemistry, The University of California San Diego, La Jolla, California 92093-0339, USA. acavalleri@ucsd.edu
authors.forename: A
authors.initials: A
authors.lastname: Cavalleri
authors.forename: C W
authors.initials: CW
authors.lastname: Siders
authors.forename: F L
authors.initials: FL
authors.lastname: Brown
authors.forename: D M
authors.initials: DM
authors.lastname: Leitner
authors.forename: C
authors.initials: C
authors.lastname: Tóth
authors.forename: J A
authors.initials: JA
authors.lastname: Squier
authors.forename: C P
authors.initials: CP
authors.lastname: Barty
authors.forename: K R
authors.initials: KR
authors.lastname: Wilson
authors.forename: K
authors.initials: K
authors.lastname: Sokolowski-Tinten
authors.forename: M
authors.initials: M
authors.lastname: Horn Von Hoegen
authors.forename: D
authors.initials: D
authors.lastname: von der Linde
authors.forename: M
authors.initials: M
authors.lastname: Kammler