Xe{sub 2} gerade Rydberg states observed in the afterglow of a microplasma by laser spectroscopy of a{sup 3}Σ{sub u}{sup +}(1{sub u},O{sub u}{sup −}) absorption in the green (545–555 nm) and near-infrared (675–800 nm)
- Laboratory for Optical Physics and Engineering, Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States)
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{sub 2} A{sup 1}Σ{sub u}{sup +}(O{sub u}{sup +})→X{sup 1}Σ{sub g}{sup +}(O{sub g}{sup +}) emission in the vacuum ultraviolet (∼172 nm), induced by laser excitation of Ω{sub g}←a{sup 3}Σ{sub u}{sup +}(1{sub u},O{sub u}{sup −}) [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{sub g}←a{sup 3}Σ{sub u}{sup +} transitions involving Ω = 0{sup ±},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(5p{sup 6} {sup 1}S{sub 0}) + Xe(5p{sup 5} 6p) and built on a predominantly A{sup 2}Π{sub 3/2g} molecular ion core. Specifically, the spectroscopic constants for the upper state of the 1{sub g}←1{sub u},O{sub u}{sup ±} absorptive transitions are determined to be T{sub e} = 13 000 ± 150 cm{sup −1}, ω{sub e}{sup ′}=120±10 cm{sup −1}, ω{sub e}{sup ′}x{sub e}{sup ′}=1.1±0.4 cm{sup −1}, D{sub e} = 3300 ± 300 cm{sup −1}, and ΔR{sub e}=R{sub e}{sup ′}−R{sub e}{sup ″}=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{sub g} and (3)O{sub g}{sup +} states of Xe{sub 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 (<4 Ǻ). Experiments in the green (545–555 nm) also provide improved absorption spectra, relative to data reported in 1986 and 1999, associated with Xe{sub 2} Rydberg states derived from the Xe(7p) orbital.
- OSTI ID:
- 22311296
- Journal Information:
- Journal of Chemical Physics, Vol. 140, Issue 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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