THE GROUND STATE SPIN-ORBIT SPLITTING OF PtH

$^{1}$ B. Kaving and R. Scullman, Can. J. Phys. 49. 2264 (1971).Author Institution: Department of Chemistry, Massachusetts Institute of TechnologyWe have observed several new bands in the electronic spectrum of PtH by laser excitation spectroscopy in the region $23,200-22,600 cm^{-1}$. For one band at $4368 \AA, a \Omega =3/2\leftarrow 2\leftarrow X^{2}\Delta_{5/2} (0,0)$ transition, it appears that the $\Omega^{\prime}=3/2$ state we have observed is the same upper state seen by Kaving and $co-workers^{1}$. The dispersed fluorescence spectrum of the 4368 {\AA} band includes a strong transition to a state at $\sim 3250 cm^{-1}$ above the $X^2\Delta_{5/2}$ ground state, probably the $X^{\prime\prime}2\Delta_{3/2}$. Our spin-orbit splitting is approximately 2000 $cm^{-1}$ larger than Kaving's prediction, but is consistent with recent theoretical calculations and the large atomic spin-orbit splitting of Pt. We will discuss this result as well as other progress made in the analysis of the electronic spectrum of PtH