NSLS-II Seminar

Beamline 9.0.1 of the Advanced Light Source at Lawrence Berkeley National Laboratory provides an intense beam of soft x-rays with energies ranging from 500 to 1500 eV. This source, with a photon flux as high as 1012 photons/second in a 50 micron spot and a coherence length as large as 10 microns, is well suited for soft x-ray scattering from few-micron sized particles. This talk serves as an overview of the tools available at beamline 9.0.1. In particular, we have optimized diffraction based imaging experiments where the x-ray phase information is provided either by proper frequency space sampling followed by iterative phase retrieval or through convolution of the sample with a complicated reference source. Using these techniques we can image both biological and material sciences samples at 10 nm resolution in two or three dimensions. In addition to imaging, we are developing techniques that utilize the scattering strength of soft x-rays to study protein crystals that are too small for traditional crystallographic methods. Using an aerodynamically focused micro-jet particle injector for sample delivery we have recorded a powder diffraction pattern from the smallest crystals (500 nm) of the largest protein (72000 atoms) ever used in powder diffraction analysis. The use of new ab initio phasing algorithms, such as compressive phase retrieval which doesn't require atomic resolution, may provide molecular envelopes from low resolution diffraction patterns.