Speaker: David Reis, SLAC National Accelerator Laboratory and Stanford University

X-ray free-electron lasers (FEL) could revolutionize our understanding of dynamics of matter at the level of electrons and atoms. They produce extremely short pulses with minimal divergence and large pulse energy, resulting in a billion times the peak brightness of storage ring-based synchrotron sources. A challenge for scientists is to make effective use of the high-brightness, especially given that the machines are also very noisy with large shot-to-shot fluctuations. This may seem incompatible with high-resolution spectroscopy of elementary excitations in solids, nonetheless, I will make the case for using FELs to study lattice dynamics. I will draw on recent results from our group where we perform high-resolution inelastic x-ray scattering in the time-domain, using relatively broad-band pulses and without the use of an analyzer. Here we generate optically broad-band vibrational coherences spanning the Brillouin zone that are subsequently probed by the scattering of a time-delayed x-ray. I will discuss implications for studying energy conversion and transport both in and out of equilibrium.

Refreshments served at 3:30 p.m.