报告摘要：

The superior brightness and short pulse duration of X-ray free electron laser (XFEL) allows it to outrun radiation damage in coherent diffractive imaging. In each imaging event, the elastic scattering terminates before photoelectron cascades commences. This “diffract-before-destroy” feature of XFEL opened up new opportunities for biological macromolecule imaging and structure studies by breaking the dose limit to samples.  In this talk, we introduce typical XFEL diffractive imaging experimental schemes, and data collection modes including serial femtosecond crystallography (SFX),  single particle diffraction, solution scattering, and mix-and-injection. We then go through specific aspects such as sample delivery and online data reduction and analysis pipeline. The serial data collection nature using XFEL pulses requires huge data volume for structure determination and the data efficiency is relatively low for weakly diffracting protein samples. These challenges motivated both analysis algorithm, software development for big data, and exploration of new diffraction schemes. Here, we showcase Click-X, EZ-hitfinder as fast, user-friendly and open source on-line data reduction tools in Python environment. SPIND was developed as a general auto-indexer for sparse diffraction data to maximize the data utilization. Convergent beam X-ray diffraction scheme(CBD) was also explored using multi-layer Laue lenses. It was demonstrated that B12 structure can be determined to resolution of ~1A from 100 patterns due to the enhanced sampling power of CBD scheme. The unique CBD geometry establishes one-to-one mapping between the real and reciprocal space. This feature enables CBD microcopy and the 3-D diffraction efficiency map can be obtained in addition to molecular structure in one process. This multi-modality imaging scheme can be applied to studies in both material and life sciences.

报告人简介：

Chufeng Li got PH.D Degreee in condensed Matter/ Biological, Department of Physics, Arizona State University, U.S (Advisors: John Spence). He worked as a research assistant in Biohysics center,BioXFEL NSFstc, USA in Arizona State University from October, 2016 to June, 2019. After that he work in Deutsches Elektronen-Synchrotron DESY, Ceter for free electron laser science(CFEL) Scientist (Serial femtosecond crystallography and Coherent Diffractive Imaging group). His multiple research include Coherent convergent Beam X-ray macro-molecular crystallography, diffraction microscopy & atomic resolution 3-D ptychography imaging et. al.

“论坛”主请人联系方式：

王振天：wangzhentian@tsinghua.edu.cn