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Optical Energy Gap and Crystal Field Excitations in CuGeO 3
Author(s) -
Dević S. D.,
Popović Z. V.,
Breitschwerdt A.,
Dhalenne G.,
Revcolevschi A.
Publication year - 1997
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(199710)203:2<579::aid-pssb579>3.0.co;2-x
Subject(s) - crystal (programming language) , absorption edge , excitation , band gap , materials science , absorption (acoustics) , field (mathematics) , crystal field theory , absorption spectroscopy , ion , range (aeronautics) , single crystal , atomic physics , atmospheric temperature range , spectral line , molecular physics , optics , chemistry , optoelectronics , crystallography , physics , mathematics , organic chemistry , quantum mechanics , meteorology , computer science , pure mathematics , composite material , programming language , astronomy
The optical transmission of CuGeO 3 single crystals was measured at different temperatures in the 250 to 900 nm spectral range. Two spectral regions were analyzed corresponding to the optical absorption edge and crystal field excitation. The energy gap values at room temperature of 3.18 and 3.54 eV as well as the energy gap temperature coefficients of 0.3 and 0.1 meV/K were determined along and perpendicular to the GeO 4 chains, respectively. In the crystal field spectral region, lowering of temperature leads to the appearance of three absorption maxima from the broad spectral feature centered at 1.76 eV at room temperature. We assign these low‐energy excitations to the crystal field splitting of 3d 9 energy levels of Cu 2+ ions in CuO 6 octahedra.