Laser fluorescence excitation spectroscopy of the GeAr van der Waals complex

Abstract

Laser fluorescence excitation spectra of the GeAr van der Waals complex, in the vicinity of the individual fine-structure lines of the Ge 4s24p5s 3P°←4s24p2 3P atomic resonance transition in the region 275–260 nm are reported. Excited-state (v′,0) progressions of bands built upon the individual J′←J″ fine-structure atomic lines were observed. In all cases, the progressions terminated with a broad, unstructured band characteristic of the existence of a barrier in the excited-state potential energy curves. Assignment of the v′ vibrational quantum numbers for the resolved bands was successfully carried out through analysis of the GeAr70,72,74,76 isotope splittings of the bands. Rotational analyses of the resolved bands were carried out, and upper- and lower-state Ω assignments and determination of the rotational constants could be performed. Transitions out of lower Ω″=0+, 1, and 0+ levels associated with the asymptotic Ge(4s24p2 3P) J″=0, 1, and 2 atomic fine-structure levels, respectively, were observed. To derive information on the relevant Ge+Ar interactions, the observed spectra were interpreted through model potential energy curves based on the isoelectronic SiAr system. The large spin–orbit interaction of the Ge atom has a strong effect on the nonbonding interactions of the fine-structure levels with the Ar atom.