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The F 2 + Center in KCl Crystals Part II: Optical Properties and Analogy with the H 2 + Molecule
Author(s) -
Aegerter M. A.,
Lüty F.
Publication year - 1971
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/pssb.2220430126
Subject(s) - excited state , luminescence , excitation , atomic physics , oscillator strength , absorption (acoustics) , dielectric , materials science , phonon , chemistry , molecular physics , condensed matter physics , physics , spectral line , optoelectronics , quantum mechanics , astronomy , composite material
F 2 +centers in KCl crystals were so far identified by one absorption band at 1.4 μm. Several new absorption bands found in the visible and near UV are studied at LHeT with an almost perfectly aligned system. Energy positions, dichroic behavior and oscillator strengths of these transitions are found in close agreement to the calculated states of the H 2 +molecule corrected with a single dielectric constant. Excitation of the lowest excited 2p σu state at 1.4 μm leads with a temperature independent quantum efficiency to the IR emission at 1.67 μm. The experimental band shapes of these IR transitions with their associated zero phonon line were analyzed using a simple model for the electron coupling. Low temperature excitation of all higher absorption states (2p πu , etc.) produces a 600 nm luminescence. At higher temperature a thermally activated process transfers the excitation energy to the lowest excited state (2p σu ) quenching the 600 nm luminescence and producing the IR emission.