Polarized electronic absorption spectra of colourless chalcocyanite, CuSO<sub>4</sub>, with a survey on crystal fields in Cu<sup>2+</sup> minerals

Autor(en)
Manfred Wildner, Gerald Giester, Monika Kersten, Klaus Langer
Abstrakt

Polarized electronic absorption spectra of colorless chalcocyanite, CuSO4, have been measured using microscope-?spectrometric techniques. The spectra are characterized by a structured and clearly polarized band system in the near-?IR spectral range with components centered at 11,?720, 10,?545, 9,?100, and 7,?320 cm-?1, which have been assigned to crystal field d-?d transitions of Cu2+ cations in pseudo-?tetragonally elongated CuO6 polyhedra with point symmetry Ci (1[n.773]?)?. The polarization behavior is interpreted based on a D2(C2'') pseudo-?symmetry. Crystal field calcns. were performed for the actual triclinic point symmetry by applying the Superposition Model of crystal fields, as well as in terms of a 'classic' pseudo-?tetragonal crystal field approach yielding the parameters Dq(eq)? = 910, Dt = 395, and Ds = 1,?336 cm-?1, corresponding to a cubically averaged Dqcub = 679 cm-?1. A comparative survey on crystal fields in Cu2+ minerals shows that the low overall crystal field strength in chalcocyanite, combined with a comparatively weak pseudo-?tetragonal splitting of energy levels, is responsible for its unique colorless appearance among oxygen-?based Cu2+ minerals. The weak crystal field in CuSO4 can be related to the lower position of the SO42-? anion compared to, e.g. the H2O mol. in the spectrochem. series of ligands.

Organisation(en)
Institut für Mineralogie und Kristallographie
Externe Organisation(en)
Technische Universität Berlin
Journal
Physics and Chemistry of Minerals
Band
41
Seiten
669-680
Anzahl der Seiten
12
ISSN
0342-1791
DOI
https://doi.org/10.1007/s00269-014-0681-1
Publikationsdatum
05-2014
Peer-reviewed
Ja
ÖFOS 2012
105116 Mineralogie, 105113 Kristallographie, 1030 Physik, Astronomie
Schlagwörter
ASJC Scopus Sachgebiete
Allgemeine Materialwissenschaften, Geochemistry and Petrology
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/cdb1fd96-2109-40d5-8994-6e79ddbbc719