OBSERVATION AND ANALYSIS OF CORE-PENETRATING RYDBERG STATES OF CALCIUM MONOFLUORIDE

Optical-optical double-resonance fluorescence excitation spectra of mo lecular Rydberg states of CaF are reported, and states up to 45500 cm- 1 above the X2SIGMA+ ground state are rotationally analyzed. The new e lectronic states are arranged into six ''core-penetrating'' Rydberg se ries by fitting their energies to the Rydberg equation using effective principal quantum numbers. The ionization potential of CaF is thereby determined to be 46998+/-5 cm-1. Spin-orbit, LAMBDA-doubling, and spi n-rotation constants are determined for a subset of the observed state s. Scaling relationships for each of these fine-structure effects are developed and shown to yield characteristic scaling parameters for eac h series. Analysis, using Ca+ atomic orbitals as a basis set for the m olecular Rydberg orbitals, shows that each of the six observed molecul ar Rydberg series correlates with a core-penetrating Rydberg series of the Ca+ ion, and that the p approximately d mixing suggested by the s pin-orbit scaling parameters of the 2PI states is consistent with that previously determined for low-lying states using a ligand-field model . The spin-orbit scaling parameter for the lone 2DELTA series is consi stent with pure l = 2 character. In the lowest-lying state of each ser ies, n approximately (n + 1) mixing is shown to account for deviations of the molecular constants from scaling predictions based on the corr esponding constants of the higher-lying states. The coefficients of sc aling relations for the LAMBDA-doubling and spin-rotation constants re veal interseries interactions which are consistent with substantial l mixing and which suggest that multistate perturbation and/or multichan nel quantum-defect analyses should be pursued.