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 4I9/2(1) →4G5/2(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) 4F3/2(1) metastable level and its excitation spectra were measured. As the result a resonance splitting of the 4I9/2(1)→4G5/2(1) crystal-field transition (Δ=2.7 cm−1) exceeding that in CaF2 (Δ=2.4 cm−1) and SrF2 (Δ=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 Δ is found to be about 3.5 cm−1 in CaF2 and 3.8 cm−1 in CdF2, respectively.