Dynamic splitting of high-lying excited state of cluster centers in the Nd3+ doped crystals with fluorite structure

Site-selective and time-resolved fluorescence and kinetic laser spectroscopy with high spectral and nanosecond temporal resolution was provided for the M and N absorption bands of the I-4(9,2)(1) --> (4)G(5,2)(1) hypersensitive transition in the CdF2 : Nd3+ (0.1 wt%) crystal at 4.2 K. Fluorescence spectra and kinetics of fluorescence decay of the lower lying (relative to the excitation wavelength) F-4(3,2)(1) metastable level and its excitation spectra were measured. As the result a resonance splitting of the 4I(9,2)(1) --> (4)G(5,2)(I) crystal-field transition (Delta = 2.7 cm(-1)) exceeding that in CaF2 (Delta = 2.4 cm(-1)) and SrF2 (Delta = 1.5 cm(-1)) was found for the Nd-Nd pair in CdF2. The variation of the splitting from CdF2 to SrF2 nicely demonstrates the R-5 dependence of the coherent quadrupole-quadrupole interaction responsible for dynamic splitting. For the quartet N centers the total splitting Delta is found to be about 3.5 cm(-1) in CaF2 and 3.8 cm(-1) in CdF2, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.