The D′⇆A′ transition in CIF

The D' (2 P-3(2)) <-> A'(2 (3)Pi) transition in ClF is studied in emission, in fluorescence, and through OODR excitation experiments. The emission spectrum is excited in a flowing Tesla discharge of CIF in half an atmosphere of Ar and is photographed at high resolution. The excitation and fluorescence spectra are obtained by pumping through perturbed levels of the B (0(+) (3)Pi) valence state. The emission data yield a detailed characterization of nu' levels 0 and 1 and nu " levels 3-8. The excitation spectra extend the nu' range to nu' = 16 and put both states on an absolute energy scale. The low-resolution fluorescence spectra span nu(") = 1-17, the upper limit of which lies within similar to 20 cm(-1) of dissociation. Key spectroscopic parameters (cm(-1)) from the study, valid for (ClF)-Cl-35-F-19, are: T-e' = 55 253, omega(e)' = 365.22, omega(e)x(e)' = 2.005, T-e(") = 18 257, omega(e)(") = 363.53, omega(e)x(e)(") = 8.30, B-e' = 0.21790, a(e)' = 0.00175, B-e(") = 0.33412, a(e)("), = 0.00631, R-e' = 2.5069 Angstrom, R-e(") = 2.024 Angstrom. A near-dissociation fit of the D' --> A' emission and fluorescence data locates the first dissociation limit at 21 495(5) cm(-1) which is lower than the accepted value, but by just one standard error. (C) 1999 Academic Press.