LASER SPECTROSCOPY STUDY OF LaF: LINKAGE OF THE TRIPLET STATE MANIFOLD WITH $0.03 cm^{-1}$ ACCURACY

$^{1.}$ K. P. Huber and G. Herzberg. ""Constants of Diatomic Molecules"", Van Nostrand, N.Y. 1979, $^{2.}$ H. Schall, Ph.D. thesis, MIT, 1985; H. Schall, C. Linton and R.W. Field, J. Mol, Spectrosc., 100,437,1983Author Institution: Department of Chemistry, Emory UniversityThe technique of selectively detected fluorescence excitation spectroscopy has been used to analyze two forbidden $d^{3}\Phi_{3-}$ and $a_{3}{^{3}}\Delta_{3}$ and $e_{3}\Phi_{3-a_{4}}^{1}\Delta_{2}$ transitions of LaF. The principal constants (in $cm^{-1}$) obtained from recent and $previous^{1-2}$ analyses are: [FIGURE] The multiplet splittings for the triplet states shows that case (a) LS coupling is a better approximation for the LaF triplet states than case (c) j-j coupling. This is in contrast to the situation for the isoclectronic molecule CcO,where j-j coupling is suitable for states arising from the 4f6s configuration. Ligand field theory calculations have been used in an attempt to provide configurational assignments for the excited states