Upcoming Events

Probing and Reconstructing Transient One-dimensional Crystalline Strains Using Time-resolved X-ray Diffraction

February 19, 2013 12:00PM to 1:00PM
Presenter 
Yuan Gao, University of Delaware
Location 
Building 432
Type 
Seminar
Series 
Ultrafast Special Interest Group Meeting Series
Abstract:
Since the late 1990s, ultrafast x-ray pulses have been used to probe impulsive strains propagating in the bulk of optically opaque materials. Time-resolved x-ray diffraction has been proven to be a very powerful tool for visualizing transient one-dimensional crystalline strains, ranging from crystal growth to shockwave production. In this presentation, I will describe a series of time-resolved x-ray diffraction experiments that visualize transient strain formation from nanometer-scaled laser-excited metallic films.

Utilizing a table top picosecond x-ray source in conjunction with a high-power optical laser system, the resulting optical pump/x-ray probe spectra reveal that the spatiotemporal structure of the transient acoustic pulse is bipolar with acoustic wave-vectors up to inverse of the film thickness. In addition, I will also discuss the real-world constraints that place limits on the validity of the reconstructed transient acoustic pulse.