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The near infrared electronic spectrum of tungsten methylidyne, WCH

TitleThe near infrared electronic spectrum of tungsten methylidyne, WCH
Publication TypeJournal Article
Year of Publication1996
AuthorsBarnes, M, Gillett, DA, Merer, AJ, Metha, GF
JournalJournal of Chemical Physics
Volume105
Pagination6168-6182
Date PublishedOct
Type of ArticleArticle
ISBN Number0021-9606
KeywordsCOMPLEXES, FREE-RADICALS, GAS-PHASE, HYPERFINE-STRUCTURE, LASER-INDUCED FLUORESCENCE, SPECTROSCOPY, STATES, SYSTEM, TRANSITION, ZNCH3
Abstract

The laser excitation spectrum of tungsten methylidyne, WCH, has been recorded in the 12 000-15 400 cm(-1) region. A total of 14 vibronic bands of WCH and 16 bands of WCD have been observed in this region. Rotational analysis shows that the ground state is (X) over tilde 3/2((2) Delta), with the substitution structure r(0)(W=C)=1.7366(5) Angstrom and r(0)(C-H)=1.076(5) Angstrom. The excited vibronic levels have been assigned, on the basis of their WCH/WCD isotope shifts and their wavelength resolved fluorescence patterns, to three electronic states, (A) over tilde 3/2((2) Delta), (B) over tilde 1/2((2) Pi), and (C) over tilde 5/2(2 Phi), at 12 090, 13 392, and 14 110 cm(-1), respectively. The wavelength resolved fluorescence spectra have also established the low-lying vibrational levels of the ground state. The ground state bending fundamental lies at 660 cm(-1), while the W-C stretching frequency is 1006 cm(-1); the corresponding frequencies in WCD are 501 cm(-1) and 953 cm(-1), respectively. No evidence for the C-H stretching frequency has been found. Emission has also been observed to a low-lying electronic state, 813 cm(-1) above the (X) over tilde 3/2 state. The pattern of rotationally resolved emission to this state clearly indicates that it is a (4) Sigma(1/2) state. Its bending frequency is 612 cm(-1), and its W-C stretching frequency is 971 cm(-1), indicating a slightly longer bond length than in the (X) over tilde 3/2 state. High resolution cw laser spectra of the (0,0) bands of the two lowest excited electronic states [(A) over tilde 3/2((2) Delta) and (B) over tilde 1/2((2) Pi)] reveal a small splitting of the four principal tungsten isotopes (W-182, W-183, W-184, and W-186) which serves to confirm the presence of tungsten in the carrier. Hyperfine splitting associated with the W-183 nucleus (I = 1/2) has been observed for the (0,0) band of the (A) over tilde 3/2- (X) over tilde 3/2 system, allowing the electron configuration of the ground state to be elucidated. (C) 1996 American Institute of Physics.

URL<Go to ISI>://A1996VM55400009