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Title: Hyperfine rather than spin splittings dominate the fine structure of the B {sup 4}Σ{sup −}–X {sup 4}Σ{sup −} bands of AlC

Laser-induced fluorescence and wavelength resolved emission spectra of the B {sup 4}Σ{sup −}–X {sup 4}Σ{sup −} band system of the gas phase cold aluminum carbide free radical have been obtained using the pulsed discharge jet technique. The radical was produced by electron bombardment of a precursor mixture of trimethylaluminum in high pressure argon. High resolution spectra show that each rotational line of the 0-0 and 1-1 bands of AlC is split into at least three components, with very similar splittings and intensities in both the P- and R-branches. The observed structure was reproduced by assuming b{sub βS} magnetic hyperfine coupling in the excited state, due to a substantial Fermi contact interaction of the unpaired electron in the aluminum 3s orbital. Rotational analysis has yielded ground and excited state equilibrium bond lengths in good agreement with the literature and our own ab initio values. Small discrepancies in the calculated intensities of the hyperfine lines suggest that the upper state spin-spin constant λ′ is of the order of ≈0.025–0.030 cm{sup −1}.
Authors:
;  [1]
  1. Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)
Publication Date:
OSTI Identifier:
22493666
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 144; Journal Issue: 3; 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; ALUMINIUM; ALUMINIUM CARBIDES; ARGON; BOND LENGTHS; COUPLING; ELECTRON BEAMS; ELECTRONS; EMISSION SPECTRA; EQUILIBRIUM; EXCITED STATES; FINE STRUCTURE; FLUORESCENCE; LASER RADIATION; RADICALS; RESOLUTION; SPIN