THE CORE-PENETRATING RYDBERG SERIES OF THE CAF MOLECULE - AT THE BORDERLINE BETWEEN VALENCE AND RYDBERG STATES

This paper reports the results of a pulsed optical-optical double resonance study of three new low energy Rydberg states and the previously known but not rotationally analyzed F2PI state [C. A. Fowler, Phys. Rev. 59, 645 (1941)] of the CaF molecule. The v = 0 levels of these four electronic states are in the energy region 36 000-39 800 cm-1 (n* almost-equal-to 3-4). Molecular constants (A,pq) or gamma, and B were measured for all of the states. The F' 2SIGMA+ state at 36 125 cm-1 (n* = 3.177) is particularly important because it is the lowest and previously unobserved member of the 'p' 2SIGMA+ Rydberg series. The assignment of the F' state as the lowest member of the 'p' 2SIGMA+ series corrects a mistaken assignment of the C' 2SIGMA+ state as the lowest member of the 'p' 2SIGMA+ series [J. E. Murphy, . M Berg, A. J. Merer, N. A. Ha s, and R. W. Field, Phys. Rev. Lett. 65, 1861 (1990)].