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Title: Study of infrared emission spectroscopy for the B{sup 1}Δ{sub g}–A{sup 1}Π{sub u} and B{sup ′1}Σ{sub g}{sup +}–A{sup 1}Π{sub u} systems of C{sub 2}

Thirteen bands for the B{sup 1}Δ{sub g}–A{sup 1}Π{sub u} system and eleven bands for the B{sup ′1}Σ{sub g}{sup +}–A{sup 1}Π{sub u} system of C{sub 2} were identified in the Fourier transform infrared emission spectra of hydrocarbon discharges. The B{sup ′1}Σ{sub g}{sup +} v = 4 and the B{sup 1}Δ{sub g} v = 6, 7, and 8 vibrational levels involved in nine bands were studied for the first time. A direct global analysis with Dunham parameters was carried out satisfactorily for the B{sup 1}Δ{sub g}–A{sup 1}Π{sub u} system except for a small perturbation in the B{sup 1}Δ{sub g} v = 6 level. The calculated rovibrational term energies up to B{sup 1}Δ{sub g} v = 12 showed that the level crossing between the B{sup 1}Δ{sub g} and d{sup 3}Π{sub g} states is responsible for many of the prominent perturbations in the Swan system observed previously. Nineteen forbidden transitions of the B{sup 1}Δ{sub g}–a{sup 3}Π{sub u} transition were identified and the off-diagonal spin-orbit interaction constant A{sub dB} between d{sup 3}Π{sub g} and B{sup 1}Δ{sub g} was derived as 8.3(1) cm{sup −1}. For the B{sup ′1}Σ{sub g}{sup +}–A{sup 1}Π{sub u} system, only individual band analyses for each vibrational level in the B′{sup 1}Σ{sub g}{supmore » +} state could be done satisfactorily and Dunham parameters obtained from these effective parameters showed that the anharmonic vibrational constant ω{sub e}x{sub e} is anomalously small (nearly zero). Inspection of the RKR (Rydberg-Klein-Rees) potential curves for the B{sup ′1}Σ{sub g}{sup +} and X{sup 1}Σ{sub g}{sup +} states revealed that an avoided crossing or nearly avoided crossing may occur around 30 000 cm{sup −1}, which is responsible for the anomalous molecular constants in these two states.« less
Authors:
; ;  [1] ;  [2]
  1. Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, 700-8530, Okayama (Japan)
  2. Department of Chemistry and Biochemistry, Old Dominion University, 4541 Hampton Boulevard, Norfolk, Virginia 23529-0126 (United States)
Publication Date:
OSTI Identifier:
22493728
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 144; Journal Issue: 6; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; EMISSION SPECTRA; EMISSION SPECTROSCOPY; FORBIDDEN TRANSITIONS; FOURIER TRANSFORMATION; G STATES; GLOBAL ANALYSIS; HYDROCARBONS; INFRARED SPECTRA; L-S COUPLING; PERTURBATION THEORY; POTENTIALS