NSLS-II Colloquium Series

The possibility of out-running radiation damage by the "diffract-and-destroy method, using femtosecond pulses of either electrons or hard X-rays, opens completely new vistas for imaging molecular dynamics at atom resolution and sub-picosecond speeds (1). First, I'll compare high-energy electron beams for this purpose, and compare them in regard to damage mechanisms and time-scales with XFEL radiation. I'll suggest a fast mode of image formation which provides high resolution despite the use of the large incoherent photocathode. I'll then review our work using the hard X-ray pulsed laser at SLAC within our BioXFEL 6-campus NSF consortium (http://www.bioxfel.org), aimed at the application of X-ray lasers (XFELs) to Structural Biology. I'll show molecular movies from light-sensitive proteins with 150 fs time resolution and near-atomic spatial , using both crystals and solution scattering obtained from the LCLS XFEL at SLAC, and very recent single-particle virus images (one virus per shot) showing dynamics. I'll discuss work in my lab on methods for hydrated sample delivery for an XFEL, and the compact IC XFEL under construction on the ASU campus, which uses a laser as an undulator. Finally, I'll review a recent proposal for the use of intensity interferometry to analyze the angular dependence of inner-shell X-ray fluorescence from a molecule. See Google Scholar for references and the many collaborators whom I thank.

1. J.Spence. XFELS for structure and dynamics in biology. IUCrJ 4, 322 (2017).