TY  - JOUR
A1  - Mattern, Maximilian
A1  - Reppert, Alexander von
A1  - Zeuschner, Steffen Peer
A1  - Herzog, Marc
A1  - Pudell, Jan-Etienne
A1  - Bargheer, Matias
T1  - Concepts and use cases for picosecond ultrasonics with x-rays
T2  - Photoacoustics
N2  - This review discusses picosecond ultrasonics experiments using ultrashort hard x-ray probe pulses to extract the transient strain response of laser-excited nanoscopic structures from Bragg-peak shifts. This method provides direct, layer-specific, and quantitative information on the picosecond strain response for structures down to few-nm thickness. We model the transient strain using the elastic wave equation and express the driving stress using Gruneisen parameters stating that the laser-induced stress is proportional to energy density changes in the microscopic subsystems of the solid, i.e., electrons, phonons and spins. The laser-driven strain response can thus serve as an ultrafast proxy for local energy-density and temperature changes, but we emphasize the importance of the nanoscale morphology for an accurate interpretation due to the Poisson effect. The presented experimental use cases encompass ultrathin and opaque metal-heterostructures, continuous and granular nanolayers as well as negative thermal expansion materials, that each pose a challenge to established all-optical techniques.
KW  - Picosecond ultrasonics
KW  - Ultrafast x-ray diffraction
KW  - Ultrafast x-ray
KW  - scattering
KW  - Ultrafast photoacoustics
KW  - Nanoscale heat transfer
KW  - Negative
KW  - thermal expansion
Y1  - 2023
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/64324
SN  - 2213-5979
VL  - 31
PB  - Elsevier
CY  - Amsterdam
ER  -