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Light-induced valence-state switching in BaFCl:La and SrFCl:La

Matsarski, Marie
Mohnhaupt, K. M.
Published in Physical Review. B, Condensed Matter. 2003, vol. 68, no. 20, p. 205113
Abstract A tetragonal La[2+] center (symmetry C[4v]) was identified in single crystals of BaFCl and SrFCl doped with lanthanum with the aid of electron paramagnetic resonance (EPR)/electron-nuclear double resonance (ENDOR). This center forms a donor-acceptor couple with initially present F(F-) centers. Switching takes place by illumination of appropriate wavelength. The kinetics of the process was monitored by EPR as La[2+] and the unswitched F center are paramagnetic. The results of our experimental investigation of this kinetics are presented. A foregoing spectroscopic characterization of the La[2+] center allowed one to identify a d-d (the B[1]-E) transition, a charge-transfer band (for BaFCl at 10 940 cm[-1] and at 17 890 cm[-1], respectively) and to obtain a value of 710 cm[-1] for the spin-orbit coupling constant in the ground state. In order to narrow the choice of possible acceptor-donor partners a detailed EPR/optical search was further done to identify a number of lattice defects and oxygen centers—in addition to a La-oxygen molecular structure.
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Research group Groupe Bill
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MATSARSKI, Marie et al. Light-induced valence-state switching in BaFCl:La and SrFCl:La. In: Physical Review. B, Condensed Matter, 2003, vol. 68, n° 20, p. 205113. https://archive-ouverte.unige.ch/unige:3512

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Deposited on : 2009-10-02

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