Determination of the dielectric tensor function of triclinic CuSO4·5H2O

Höfer, Sonja; Popp, Jürgen; Mayerhöfer, Thomas G.

doi:10.1016/j.vibspec.2013.04.003

Cited by 30 publications

(28 citation statements)

References 20 publications

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“…[16]). To measure spectra along the cube face diagonals the cube was rotated by 45° (and not the polarizer).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…The latter measurements were used to prove the results of dispersion analysis since a good agreement between measured (principal) spectra and fit is only necessary but not sufficient for a meaningful result. To that end the measured spectra were compared with those calculated based on the results of dispersion analysis for the dispersion parameters employing a 4×4 matrix formalism [14] that generalizes those developed by Berreman [15] and Yeh [16].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

See 1 more Smart Citation

Complete dispersion analysis of single crystal neodymium gallate

Höfer

Uecker

Kwasniewski

et al. 2015

Vibrational Spectroscopy

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“…[16]). To measure spectra along the cube face diagonals the cube was rotated by 45° (and not the polarizer).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Theoretical Backgroundmentioning

confidence: 99%

Complete dispersion analysis of single crystal neodymium gallate

Höfer

Uecker

Kwasniewski

et al. 2015

Vibrational Spectroscopy

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“…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.…”

Section: Introductionmentioning

confidence: 98%

“…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.…”

Section: Introductionmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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Dispersion analysis of arbitrarily cut uniaxial crystals

Höfer

Uecker

Kwasniewski

et al. 2015

Vibrational Spectroscopy

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Employing Theories Far beyond Their Limits – Linear Dichroism Theory

Mayerhöfer

2018

ChemPhysChem

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Using linear polarized light, it is possible in case of ordered structures, such as stretched polymers or single crystals, to determine the orientation of the transition moments of electronic and vibrational transitions. This not only helps to resolve overlapping bands, but also assigning the symmetry species of the transitions and to elucidate the structure. To perform spectral evaluation quantitatively, a sometimes "Linear Dichroism Theory" called approach is very often used. This approach links the relative orientation of the transition moment and polarization direction to the quantity absorbance. This linkage is highly questionable for several reasons. First of all, absorbance is a quantity that is by its definition not compatible with Maxwell's equations. Furthermore, absorbance seems not to be the quantity which is generally compatible with linear dichroism theory. In addition, linear dichroism theory disregards that it is not only the angle between transition moment and polarization direction, but also the angle between sample surface and transition moment, that influences band shape and intensity. Accordingly, the often invoked "magic angle" has never existed and the orientation distribution influences spectra to a much higher degree than if linear dichroism theory would hold strictly. A last point that is completely ignored by linear dichroism theory is the fact that partially oriented or randomly-oriented samples usually consist of ordered domains. It is their size relative to the wavelength of light that can also greatly influence a spectrum. All these findings can help to elucidate orientation to a much higher degree by optical methods than currently thought possible by the users of linear dichroism theory. Hence, it is the goal of this contribution to point out these shortcomings of linear dichroism theory to its users to stimulate efforts to overcome the long-lasting stagnation of this important field.

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Determination of the dielectric tensor function of triclinic CuSO4·5H2O

Cited by 30 publications

References 20 publications

Complete dispersion analysis of single crystal neodymium gallate

Complete dispersion analysis of single crystal neodymium gallate

Dispersion analysis of arbitrarily cut uniaxial crystals

Employing Theories Far beyond Their Limits – Linear Dichroism Theory

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