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Reducing the background of ultra‐low‐temperature X‐ray diffraction data through new methods and advanced materials
Author(s) -
McMonagle Charles James,
Probert Michael Richard
Publication year - 2019
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576719003078
Subject(s) - diffraction , materials science , collimator , helium , beryllium , scattering , x ray crystallography , dilution refrigerator , intensity (physics) , optics , analytical chemistry (journal) , refrigerator car , chemistry , physics , atomic physics , nuclear physics , chromatography , thermodynamics
New methods and advanced materials that significantly reduce the background when collecting single‐crystal X‐ray diffraction data at ultra‐low temperatures using a closed‐cycle helium refrigerator are presented here. These include a magnetically controlled internal beamstop and a separate internal collimator that together completely remove the scattering contribution to the background from the beryllium vacuum chamber. Additionally, a new radiation shield made from flexible graphite significantly reduces the background and maintains excellent thermal properties. In combination these improvements have led to a sixfold reduction in the average intensity and a 15‐fold reduction in peak intensity of the background observed for diffraction experiments conducted with a closed‐cycle helium refrigerator. Moreover, access to ultra‐low base temperatures, 2.05 K, has been maintained. The design and implementation of these methods are discussed along with a case study of vitamin C to demonstrate the effectiveness of the improvements.