Direct observation of dynamics of thermal expansion using pump-probe high-energy-resolution x-ray diffraction

• Published in: Physical review. B, Condensed matter and materials physics Vol. 86; no. 5
• Main Authors: Stoupin, S., March, A. M., Wen, H., Walko, D. A., Li, Y., Dufresne, E. M., Stepanov, S. A., Kim, K.-J., Shvyd'ko, Yu. V., Blank, V. D., Terentyev, S. A.
• Format: Journal Article
• Language: English
• Published: 02-08-2012
• Subjects: Asymptotic properties; Condensed matter; Crystal lattices; Diffraction; Reflectivity; Strain; Thermal expansion; X-rays
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.86.054301

Time evolution of thermal expansion in the crystal lattice of diamond was studied on the time scale from 100 ps to 18 mu s upon heating of the crystal through the entire thickness by a penetrating optical laser pulse of [approximate]8 ps in duration. Bragg reflectivity curves were measured at different instants of time using pump-probe high-energy-resolution x-ray diffraction with [Asymptotically = to]10 super(-8) strain sensitivity. The observed time-dependent variation of Bragg reflectivity was found to be in agreement with dynamical diffraction calculations for a crystal with propagating strain generated by thermally induced stress. The strain propagated at the speed of sound for longitudinal waves from both crystal surfaces into the bulk.