Optical-optical double resonance polarization spectroscopy of the B-1 Pi state of (KRb)-K-39-Rb-85

High resolution spectra of the B (1) Pi<--X (1) Sigma(+) transition of the (KRb)-K-39-Rb-85 molecule have been measured with the technique of Doppler-free optical-optical double resonance polarization spectroscopy. Molecular constants of the B (1) Pi(v'=0-12) levels are determined, and the RKR potential is calculated. A number of irregularities in the energies of B (1) Pi state levels and intensity anomalies are observed. The energy shifts of the e and f levels of the B (1) Pi state are studied, and the perturbations between the B (1) Pi and (3) Sigma(+) states and between the B (1) Pi and (3) Sigma(+) states are identified. Several transitions to the (3) Pi(1) and (3) Sigma(+) states are also observed, and the molecular constants of the (3) Pi(1) and (3) Sigma(+) states are evaluated. The single rovibrational level B (1) Pi(v'=2, J'=41) is selectively excited by a single frequency laser chopped by an electro-optical modulator, and the decay time of the resulting fluorescence is measured at various pressures. From the Stern-Volmer plot, the radiative lifetime and the collisional cross section of the fluorescence quenching are determined to be 11.6 ns and 29 Angstrom(2), respectively. The intensity distribution of the dispersed fluorescence of the B (1) Pi(v'=2, J=41)-->X (1) Sigma(+)(v ''=0-11, J ''=42) transitions is in very good agreement with the calculated values of nu(4)\[v'=2\v '']\(2) The magnitude of the transition dipole moment is determined to be 9.2 D in the range of 4.08 Angstrom<R<4.73 Angstrom. These results are compared with the results of recent ab initio calculations. (C) 1996 American Institute of Physics.