ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Spectroscopic constants (De, re, ωe, μe) are presented for the ground and low-lying states of the monoxides and monosulfides of yttrium, zirconium, and niobium using large valence basis sets in conjunction with relativistic effective core potentials. For states well described by a single configuration, electron correlation is incorporated using the modified coupled-pair functional method. When several molecular states of the same symmetry or transition moments are determined, we employ state-averaged CASSCF/MRCI methods. The theoretical spectroscopic constants for the oxides are generally in excellent agreement with experiment, so that the corresponding results for the sulfides should be helpful to spectroscopists attempting to characterize these band systems. The quartet manifold of states in YO is found to lie too high to significantly affect the spectroscopy of the low-lying doublet states. Both the A 2Π–X 2Σ+ and B 2Σ+–X 2Σ+ transitions in YO are very strong, resulting in radiative lifetimes of 21 and 17 ns for the A 2Π and B 2Σ+ states, respectively. The (1)3Φ–a3Δ band system of ZrS is identified as a likely carrier of the Keenan bands observed in the infrared spectra of S stars. The theoretical De values parallel experiment, but are systematically low, as the calculations do not fully account for the large correlation contribution to the bond energy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.455060
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