Publication Date:
2014-07-01
Description:
Bound←bound transitions of the Xe dimer at small internuclear separation ( R 〈 4.0 Å) have been observed in the 545–555 nm and 675–800 nm spectral regions by laser spectroscopy in the afterglow of a pulsed Xe microplasma with a volume of ∼160 nl. Transient suppression of Xe 2 A 1 Σ u + ( O u + ) → X 1 Σ g + ( O g + ) emission in the vacuum ultraviolet (∼172 nm), induced by laser excitation of Ω g ← a 3 Σ u + ( 1 u , O u − ) [Rydberg←Rydberg] transitions of the molecule, has confirmed the existence of structure between 720 and 770 nm (reported by Killeen and Eden [J. Chem. Phys.84, 6048 (1986)]) but also reveals red-degraded vibrational bands extending to wavelengths beyond 800 nm. Spectral simulations based on calculations of Franck-Condon factors for assumed Ω g ← a 3 Σ u + transitions involving Ω = 0 ± ,1 gerade Rydberg states suggest that the upper level primarily responsible for the observed spectrum is an Ω = 1 state correlated, in the separated atom limit, with Xe (5 p 6 1 S 0 ) + Xe (5 p 5 6 p ) and built on a predominantly A 2 Π 3/2 g molecular ion core. Specifically, the spectroscopic constants for the upper state of the 1 g ← 1 u , O u ± absorptive transitions are determined to be T e = 13 000 ± 150 cm −1 , ω e ′ = 120 ± 10 cm − 1 , ω e ′ x e ′ = 1.1 ± 0.4 cm − 1 , D e = 3300 ± 300 cm −1 , and Δ R e = R e ′ − R e ″ = 0.3 ± 0.1 Å which are in general agreement with the theoretical predictions of the pseudopotential hole-particle formalism, developed by Jonin and Spiegelmann [J. Chem. Phys.117, 3059 (2002)], for both the (5)1 g and ( 3 ) O g + states of Xe 2 . These spectra exhibit the most extensive vibrational development, and provide evidence for the first molecular core-switching transition, observed to date for any of the rare gas dimers at small R (
Print ISSN:
0021-9606
Electronic ISSN:
1089-7690
Topics:
Chemistry and Pharmacology
,
Physics
