Laser Spectroscopy of GdO: Ligand Field Assignments of 4f7(8S)6p ← 4f7(8S)6s Transitions

✍ Scribed by L.A. Kaledin; M.G. Erickson; M.C. Heaven

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 510 KB
• Volume: 165
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1994.1136

✦ Synopsis

Wavelength-resolved fluorescence excitation techniques have been used to record three electronic transitions of (\mathrm{GdO}) at a resolution of (0.03 \mathrm{~cm}^{-1}). Previous analyses of two bands (Yu.N. Dmitriev et al, Acta Phys. Hung. 55, 467-479 (1984) and P. Carette et al., J. Mol. Spectrosc. 124, 243271 ( 1987)) have been extended with some corrections to the assignments of low- (J) lines. Improved molecular constants were obtained for the (X^{9} \Sigma^{-})and (a^{7} \Sigma^{-})states that correlate with (\mathrm{Gd}^{2+}) (\left(4 f^{7}\left({ }^{8} S\right) 6 s\right) \mathrm{O}^{2-}). A large difference between the spin-orbit coupling constants for (X^{9} \Sigma^{-}(\lambda=) (\left.-0.10353 \mathrm{~cm}^{-1}\right)) and (a^{7} \Sigma^{-}\left(\lambda=-0.64712 \mathrm{~cm}^{-1}\right)) was noted. This difference was ascribed to the fact that the (X) state is almost pure (f^{7}\left({ }^{8} S\right)), whereas the (a) state has partial (f^{7}\left({ }^{6} P\right)) character. Analysis of the (a) state required off-diagonal matrix elements of the spin-orbit interaction, evaluated using sixth-order degenerate perturbation theory, for treatment of nonrotating molecular spinorbit intervals. In principle, these elements are needed to describe (\mathbb{\Sigma}) states of septet and higher multiplicity. Energy intervals reflecting the structure (\mathrm{Gd}^{2+}\left(4 f^{7}\left({ }^{8} S\right) 6 p\right) \mathrm{O}^{2-}) were recognized among the excited states of GdO. Overall, the results were consistent with ligand field theory models for the excited states of lanthanide oxide ( (L n O) ) molecules. ct 1994 Academic Press. Inc.