X-ray Birefringence Imaging of Materials with Anisotropic Molecular Dynamics.
The X-ray birefringence imaging (XBI) technique, reported very recently, is a sensitive tool for spatially resolved mapping of the local orientational properties of anisotropic materials. In this paper, we report the first XBI measurements on materials that undergo anisotropic molecular dynamics. Using incident linearly polarized X-rays with energy close to the Br K-edge, the X-ray birefringence is dictated by the orientational properties of the C-Br bonds in the material. We focus on two materials (urea inclusion compounds containing 1,8-dibromooctane and 1,10-dibromodecane guest molecules) for which the reorientational dynamics of the brominated guest molecules (and hence the reorientational dynamics of the C-Br bonds) are already well characterized by other experimental techniques. The XBI results demonstrate clearly that, for the anisotropic molecular dynamics in these materials, the effective X-ray optic axis for the X-ray birefringence phenomenon is the time-averaged resultant of the orientational distribution of the C-Br bonds.
†School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales.|‡Centre for NanoHealth, Institute of Life Science 2, Swansea University, Swansea SA2 8PP, Wales.
Benjamin A
BA
Palmer
†School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales.
Gregory R
GR
Edwards-Gau
†School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales.
Benson M
BM
Kariuki
†School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales.
Kenneth D M
KD
Harris
§Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, England.
Igor P
IP
Dolbnya
§Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, England.
Stephen P
SP
Collins
§Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, England.
John P
JP
Sutter
D000473:Alkanes / Q000737:chemistry; D016880:Anisotropy; D001718:Birefringence; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D061848:Optical Imaging; D014508:Urea / Q000737:chemistry; D014965:X-Rays
D000473:Alkanes; D014508:Urea
Bond Orientations; Molecular Crystals; Molecular Dynamics; Phase Transitions; X-ray Birefringence Imaging