* PHYSICS SEMINAR *

Coherent X-ray Diffraction Microscopy for Nano-Structures and Biological Specimens

연사: Changyong Song[University of California, Los Angeles]

일시: 2007 년 4 월 17 일 15:00 ~

장소: 공학3동 201호 세미나실

ABSTRACT:

X-ray diffraction has long been used as a non-invasive and transmissive atomic resolution probe. Focused efforts to manipulate nano-scale structures have driven the need for a versatile probe capable of non-destructive, sample environment adaptive, and embedded structure sensitive imaging at a nanometer resolution. The difficulty in using diffraction for imaging is that the measured intensity records only the amplitude of the diffractive wave-field and not the phase. The imaging of an object is a daunting task without this phase information, and in general its applications have been restricted to crystalline specimens. Coherent diffraction microscopy employs a numerical phase retrieval process independent of optical elements, and paves a route to an atomic resolution microscope. This new imaging technique - with significant developments including a new phase retrieval algorithm, exact oversampling of the diffracted intensity, and protein specific labeling - has allowed us to tackle various intriguing scientific problems in nano-structured materials, bio-minerals, and single biological cells at an appropriate length scale. Exciting scientific opportunities with the newly developed X-ray Free Electron Laser (XFEL) facilities will also be introduced

문의처: 이기봉(054-279-2068, kibong@postech.ac.kr)