Dispersion analysis of triclinic K2Cr2O7

Dispersion analysis of arbitrarily cut uniaxial crystals

“…The c-axis is parallel to two cube faces and has an angle of 38° to the other cube faces. A possible sequence of rotation to address all cube faces is presented in [2][3][4]. The little shoulder at roughly 850 cm -1 (marked in spectrum R s 0 0 0) could not be resolved by the fit.…”

“…A detailed description of the formalism to calculate the reflection spectra can be found in [2][3][4].…”

“…If dispersion analysis is able to determine the orientations of the transition moments in the triclinic crystals, as was shown in [2] and [3], it should be possible to do the same also for crystals with higher symmetry. Since in such crystals the transition moments are oriented parallel to certain symmetry elements (rotation axes and mirror planes), it should be possible to find out by dispersion analysis not only the dispersion parameters, but simultaneously the crystal orientation and symmetry (certainly not the full symmetry, since e.g.…”

“…In [2] and [3] we developed a scheme to perform dispersion analysis on triclinic crystals. With CuSO 4 •5H 2 O we investigated a representative of a triclinic crystal which shows almost orthorhombic-like behavior in the IR spectral region due to only weakly distorted 2 4 SO  tetrahedrons.…”

“…In the end, we aim at being able to differentiate between cubic, uniaxial, orthorhombic, monoclinic and triclinic crystal symmetry by adapting the measurement and evaluation scheme developed by [2,3] to the respective crystal class. As a first step in this direction, we need to evaluate how reliable we can perform dispersion analysis for the individual crystals classes while being able to determine crystal structure and orientation.…”