ELECTRONIC COHERENT ANTI-STOKES-RAMAN SPECTROSCOPY IN CEF3

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 (lambda-1 almost-equal-to 476 nm, lambda-2 = 532 nm) and near-ultraviolet (lambda-1 = 355 nm, lambda-2 almost-equal-to 385 nm) lasers. The enhancement of the third-order susceptibility owing to the electronic transitions, \chi-(3)R/chi-(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, sigma-zz(2161 cm-1) = (5.0 +/- 1.1) x 10(-30) cm2 and sigma-zz(2239 cm-1) = (1.9 +/- 0.7) x 10(-30) cm2. One could calculate both the absolute magnitude and the dispersion of \chi-(3)R\max by modeling the virtual intermediate states as a single degenerate 5d state at 45 000 cm-1.