Precise characterization of the B (1/2) and C (3/2) states of XeF from a deperturbation analysis of the B→X spectrum of 136XeF

The B ((1)/(2)) and C ((3)/(2)) ion-pair excited states of XeF are coupled by the rotational Hamiltonian, producing perturbations in the rotational structure of B --> X((2)Sigma(+)) transitions involving upsilon' levels <5. Five upsilon'-upsilon" bands in the B --> X emission spectrum of the single isotopomer (XeF)-Xe-136-F-19 are analyzed by a deperturbation model to yield improved spectroscopic parameters (cm(-1)) for the low-v regions of the B and C states: For B, omega(e) = 308.09, omega(e)omega(e) = 1.480, B-e = 0.145 29, and alpha(e) = 0.000 675; for C, omega(e) = 345.1; omega(e)omega(e) = 2.10, B-e = 0.165 42, and alpha(e) = 0.001 48. The C state lies 797 cm(-1) below the B state, with R-e = 2.473 Angstrom. The electronic perturbative coupling element for B-C interactions is 1.632, which is 6% below the simple Hund's case c-based prediction (root3) and just 3% greater than an estimate obtained from a more elaborate case a approach.