Search for Helices of Atomic Electron Density As a Structural Basis of Optical Activity in α-TeO2 Crystal

An X-ray diffraction study of the atomic structure of paratellurite (α-TeO2) crystal in the temperature range of 86–500 K has been performed. Regions of atomic electron density, shaped as helices with axes oriented parallel and perpendicular to the optical axis, are selected; these regions are found to be the structural basis of the optical activity of crystal. All helices turned out to be right-handed. The values of optical rotation in the directions parallel and perpendicular to the optical axis have been calculated using structural data. These values have identical signs, as was suggested proceeding from the identical twist of electron density helices.