Publication Date:
2015-03-18
Description:
Rotationally resolved high-resolution fluorescence excitation spectra of the 0–0 band of the B ̃ 2 E ′ ← X ̃ 2 A 2 ′ transition of the 15 N substituted nitrate radical were observed for the first time, by crossing a jet-cooled molecular beam and a single-mode dye laser beam at right angles. Several thousand rotational lines were detected in the 15 080–15 103 cm −1 region. We observed the Zeeman splitting of intense lines up to 360 G in order to obtain secure rotational assignment. Two, nine, and seven rotational line pairs with 0.0248 cm −1 spacing were assigned to the transitions from the X ̃ 2 A 2 ′ ( υ ″ = 0, k ″ = 0, N ″ = 1, J ″ = 0.5 and 1.5) to the 2 E 3 / 2 ′ ( J ′ = 1.5), 2 E 1 / 2 ′ ( J ′ = 0.5), and 2 E 1 / 2 ′ ( J ′ = 1.5) levels, respectively, based on the ground state combination differences and the Zeeman splitting patterns. The observed spectrum was complicated due to the vibronic coupling between the bright B ̃ 2 E ′ ( υ = 0) state and surrounding dark vibronic states. Some series of rotational lines other than those from the X ̃ 2 A 2 ′ ( J = 0.5 and 1.5) levels were also assigned by the ground state combination differences and the observed Zeeman splitting. The rotational branch structures were identified, and the molecular constants of the B ̃ 2 E 1 / 2 ′ ( υ = 0) state were estimated by a deperturbed analysis to be T 0 = 15 098.20(4) cm −1 , B = 0.4282(7) cm −1 , and D J = 4 × 10 −4 cm −1 . In the observed region, both the 2 E 1 / 2 ′ and 2 E 3 / 2 ′ spin-orbit components were identified, and the spin-orbit interaction constant of the B ̃ 2 E ′ ( υ = 0) state was estimated to be −12 cm −1 as the lower limit.
Print ISSN:
0021-9606
Electronic ISSN:
1089-7690
Topics:
Chemistry and Pharmacology
,
Physics
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