LASER SPECTROSCOPIC STUDY OF THE SiAr VAN DER WAALS COMPLEX
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Date
2002
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Publisher
Ohio State University
Abstract
Laser fluorescence excitation spectra of the SiAr van der Waals complex, in the vicinity of the Si ${^{3}}D^{0} \leftarrow {^{3}}P$ atomic resonance transition near 220.7 nm are reported. At low resolution, a single excited state $(v^{\prime},0)$ progression of bands terminating in a dissociation continuum is observed. Several weaker bands associated with many of these strong bands are found in scans at higher resolution. A transition to an excited ${^{3}}\Sigma^{-}$ state which correlates with the excited $Si({^{3}}D^{0})+Ar$ asymptote was assigned, and a rotational and vibrational analysis of the observed bands was carried out. The dissociation energies of the $\Omega = 0^{+}$ components of the ground $X^{3}\Sigma^{-}$ and excited ${^{3}}\Sigma^{-}$ states were determined [$D^{\prime\prime}_{0} = 178.8 \pm 0.4$ and $D^{\prime}_{0} = 122.5 \pm 0.4 cm^{-1}$]. Ab initio calculations of the SiAr $X^{3}\Sigma^{-}$ and $A^{3}\Pi$ electronic states correlating with the ground-state $Si(3s^{2}3p^{2} {^{3}}P) + Ar$ asymptote were also carried out. The potential energy curves of the definite-$\Omega$ states were computed and used to estimate the dissociation energy, rotational constant, and phenomenological spin-spin interaction in the $X^{3}\Sigma^{-}$ state. These parameters were found to be in resonable agreement with the experimental determinations.
Description
Author Institution: Department of Chemistry, The Johns Hopkins University; Department of Chemistry and Biochemistry, The University of Maryland