Optical properties of chromate ion in potassium sulphate crystals
TL;DR: In this paper, the authors show that a fine structure of alternately weak and strong lines is present in the spectrum of potassium sulphate crystals containing chromate ions, and that the strong lines are due to transitions from the ground state to vibrational levels of the excited state.
About: This article is published in Chemical Physics Letters.The article was published on 1972-02-01. It has received 9 citations till now. The article focuses on the topics: Ground state & Excited state.
Citations
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TL;DR: In this paper, a model that assumes that the dichromate ion enters the lattice by replacing two halide ions with no charge compensating vacancy satisfactorily explains all the experimental results.
Abstract: Optical and infrared spectra of dichromate ions in KCl, KBr, and KI matrices are reported. Optical spectra of Cr2O7−− consist of three absorption bands that are attributed to the electronic transitions 1A 1(t16)→1T 2(t15t21); 1A 1(t61)→1E(t15t21) or 1T 2(t15t21); and 1A 1(t16) →1T 2(t15e1) on the basis of molecular orbitals. Fine structure caused by coupled vibration‐electronic transitions is observed in the 1A 1(t16)→1T 2(t15e1) band. This fine structure further splits at low temperature (77°K) because of the symmetry lowering of the dichromate ion from Td to C3v. Infrared spectra show a number of lines. A model that assumes that the dichromate ion enters the lattice by replacing two halide ions with no charge compensating vacancy satisfactorily explains all the experimental results.
18 citations
TL;DR: In this paper, the reduction in symmetry from the fully octahedral symmetry of the alkali halides induces a wide range of effects, including the lifting of electronic and vibrational degeneracies, the occurrence of spin-forbidden transitions, and highly anisotropic g- and hyperfine-tensors.
14 citations
TL;DR: In this paper, the vibrational frequencies of CrO ion embedded in orthorhombic sulphates have been determined from optical and infrared absorption studies, where the electronic levels have a superposed vibration structure, in the regions 2300 to 2750 A and 3300 to 3850 A, with alternate strong and weak lines.
Abstract: Vibrational frequencies of CrO ion embedded in orthorhombic sulphates have been determined from optical and infrared absorption studies. In the optical absorption spectra, the electronic levels are found to have a superposed vibration structure, in the regions 2300 to 2750 A and 3300 to 3850 A, with alternate strong and weak lines. The set of strong lines is interpreted to be due to the transitions from the ground electronic state to the vibrational levels of the excited state, whereas the set of weaker lines is assigned to the transitions from one of the vibrational levels of the ground electronic state to the vibrational levels of the upper excited electronic state. It is found that the IR forbidden bands become allowed and are observed in these lattices. No splitting is observed in the degenerate modes in IR spectra.
Es wurden die Schwingungsfrequenzen des in rhombischen Sulfaten eingebauten CrO. Ions aus optischen und Infrarotabsorptionsuntersuchungen bestimmt. In den optischen Spektren wurde gefunden, das die Elektronenniveaus eine uberlagerte Schwingungsstruktur in den Bereichen 2300 bis 2750 A und 3300 bis 3850 A aufweisen, mit abwechselnd starken und schwachen Linien. Der Satz der starken Linien wird als Ubergange vom elektronischen Grundzustand zu Schwingungszustanden des angeregten Niveaus gedeutet, wahrend der Satz der schwacheren Linien Ubergangen von einem der Schwingungszustande des Grundzustandes zu Schwingungszustanden des oberen, angeregten Elektronenzustands zugeordnet wird. Es wird gefunden, das die IR-verbotenen Banden erlaubt werden und in diesen Gittern beobachtet werden konnen. In den entarteten Moden des 1R-Spektrums wird keine Aufspaltung beobachtet.
8 citations
TL;DR: Two electronic bands arising from the t1 → 2e and t 1 → 3t2 transitions are observed in the region ≈ 360 nm and ≈ 250 nm in alkali halide crystals doped with Cr2O2−7 as discussed by the authors.
7 citations
References
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TL;DR: An S.C.F.-M.O.-L.A. calculation in the Roothaan-Popie scheme, using the Pariser-Parr approximations, has been carried out for the ions [CrO4]-- and [MnO4]- and the necessary integrals have been evaluated semi-empirically as discussed by the authors.
Abstract: An S.C.F.-M.O.-L.C.A.O. calculation in the Roothaan-Popie scheme, using the Pariser-Parr approximations, has been carried out for the ions [CrO4]-- and [MnO4]-. The necessary integrals have been evaluated semi-empirically. For a more exact evaluation of the spectral transitions, a configuration interaction calculation, extended to the most important mono-excited configurations, has been performed. The order of levels previously suggested by Ballhausen and Liehr and other authors is confirmed by the results of the calculations. A new spectral assignment is presented, attributing to each observed absorption band two electronic transitions occurring between one of the occupied M.O.'s (t 1, 2t 2, 1t 2) and the two lowest empty M.O.'s (2e, 3t 2).
70 citations
53 citations
TL;DR: In this article, a linear relation was established between the M.O. energies and the oxidation number and electron configuration of the central ion of tetroxo complexes, and the extent of π-bonding effects was quantitatively studied and compared with the analogous situation in the hexahalides.
Abstract: M.O. theory is used for classifying the energy levels of tetroxo complexes, and linear relations are shown to exist between the M.O. energies (and hence the electro-negativities) and the oxidation number and electron configuration of the central ion. The extent of π-bonding effects is quantitatively studied and compared with the analogous situation in the hexahalides.
41 citations