Open AccessBeam‐size effects in radiation damage in insulin and thaumatin crystals
Author(s) -
Wagner A.,
Tomizaki T.,
Oetiker M.,
SchulzeBriese C.
Publication year - 2005
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049505003298
Subject(s) - materials science , irradiation , radiation , optics , beam (structure) , radiation damage , wedge (geometry) , photoelectric effect , optoelectronics , physics , nuclear physics
Cryocooled insulin and thaumatin crystals were irradiated in a series of alternating data collections and high‐dose‐rate exposures using either a vertically focused or vertically defocused beam. The main result is that the radiation damage is limited to the exposed region, which can be explained by the short range of the photoelectrons and the Auger electron cascade produced by light elements. Consequently, the unexposed angular range provides significantly improved data quality and electron density compared with previously exposed angular wedges of the crystal when a vertically focused beam is used, while no differences are observed between a fresh wedge and an exposed region for the vertically defocused beam. On the other hand, the focused beam provides higher I /σ I ratios at high resolution than homogeneous sample illumination but also causes more rapid sample deterioration.