ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Inter-Rydberg transitions of Ar2 in the green (∼460–530 nm) have been studied by intracavity, laser absorption spectroscopy. All five Hund's case (c) members of the Aπu5p manifold, predicted by the guidelines established by Mulliken [J. Chem. Phys. 52, 5170 (1970)] for Xe2 and later adapted by Chang and Setser [J. Chem. Phys. 69, 3885 (1978)] for Ar2, have been observed. The molecular transitions originate from Aσg4s(1u,0−u) and terminate on the A2 Σ+ 1/2 u ion core, 3Πg on the A2 Σ+ 1/2 u ion co-derived (5p Rydberg electron 0−g, 0+g, 2g, 1g, and 1g. Transitions involving three of these are strongly red degraded [revealing that Re4s(1u, 0−u) 〈Re5p(0−g) (approximately-less-than)Re(0+g)〈Re(1g upper)] whereas the bands associated with the 2g and lowest 1g levels are not. Analysis of newly observed hot bands (Δv≡v'−v‘〈0) yields the following vibrational constants for ω‘e =297.2±1.0 cm−1, ω‘e x‘e =3.3±0.4 cm−1, and ω‘e y‘e =0.08±0.05 cm−1. Several clear vibrational sequences are observed and tentative assignments for the Aπu5p separated atom limits are reported. The 0−g, 0+g, (2g, 1g), and 1g (upper) states apparently correlate (in the separated atom limit) with Ar(1S0)+Ar 5p[ 1/2 ]1, [ (5)/(2)]2, [ (5)/(2) ]3, and [ (3)/(2) ]1, respectively, which is consistent with the known 4p, 5p→4s oscillator strengths, the Ar 3p5 5p fine structure splittings, and the measured energy defects between the Aπu5p substrates. Rather than being degenerate at small R, the 0−g and 0+g states of the πu5p manifold are split by 247 cm−1 near Re. Bandheads arising from the Aσu5p(0−g)←Aσg4s (1u, 0−u) transition have also been observed. Calculations show that the Aσu5p(0−g) state dissociation energy (D0(approximately-equal-to)1.0 eV) is noticeably smaller than that for the Aπu5p levels (D0=1.26±0.01 eV).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.455386
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