Electronic coherent anti-Stokes Raman spectroscopy in CeF_3

Abstract

The coherent anti-Stokes Raman spectroscopy (CARS) of electronic states of the Ce3+ ion in a CeF3 crystal at 3.8 K is reported. CARS resonances involving the ground state of the 2F5/2 manifold and the Stark components of the 2F7/2 manifold at 2161 and 2239 cm−1 have been detected. Measurements were made with both visible (λ1 ≈ 476 nm, λ2 = 532 nm) and near-ultraviolet (λ1 = 355 nm, λ2 ≈ 385 nm) lasers. The enhancement of the third-order susceptibility owing to the electronic transitions, |χ(3)R/χ(3)NR|max, is as great as 4.8. This represents an order-of-magnitude increase over that in singly resonant electronic CARS experiments in other rare-earth crystals. The CARS data also yielded accurate measurements of the Ce3+ electronic Raman cross sections. In the visible region, σzz(2161 cm−1) = (5.0 ± 1.1) × 10−30 cm2 and σzz(2239 cm−1) = (1.9 ± 0.7) × 10−30 cm2. One could calculate both the absolute magnitude and the dispersion of |χ(3)R|max by modeling the virtual intermediate states as a single degenerate 5d state at 45 000 cm−1.