Laser-induced fluorescence spectroscopy of jet-cooled SiC sub 2

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.461476· OSTI ID:5797319

Butenhoff, T J; Rohlfing, E A ^[1]

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1. Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551 (US)

We present a spectroscopic study of the {ital {tilde A}} {sup 1}{ital B}{sub 2}{l arrow}{ital {tilde X}} {sup 1}{ital A}{sub 1} system of jet-cooled SiC{sub 2} that includes both laser-induced fluorescence (LIF) excitation and dispersed fluorescence (DF) spectra. Rotational analysis of several previously unobserved bands in the LIF spectrum enables us to reassign the vibronic structure in the {ital {tilde A}} {sup 1}{ital B}{sub 2}{l arrow}{ital {tilde X}} {sup 1}{ital A}{sub 1} system and gives an accurate term energy for the low-frequency, antisymmetric mode in the ground state, G(0,0,1)=196.37(4) cm{sup {minus}1}. Analysis of DF spectra from ten different {ital {tilde A}}-state levels yields vibrational term energies for 43 levels in the ground state, including (0,0,{ital v}{sup {double prime}}{sub 3}) levels as high as {ital v}{sup {double prime}}{sub 3}=16. The rapidly decreasing level spacings in the (0,0,{ital v}{sup {double prime}}{sub 3}) progression, coupled with a dramatic decrease in the small inertial moment, give insight into the extreme anharmonic potential surface of the ground state. These data also provide indirect evidence for the onset of large-amplitude pseudorotation that samples both cyclic and linear minima. In contrast, the {ital {tilde A}} state is quite harmonic at the cyclic minimum, indicative of a more substantial barrier between the two isomers.

• OSTI ID: 5797319
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 95:1; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
CARBIDES
CARBON COMPOUNDS
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
EXCITED STATES
FLUORESCENCE
JETS
LASER RADIATION
LUMINESCENCE
MOLECULES
RADIATIONS
ROTATIONAL STATES
SILICON CARBIDES
SILICON COMPOUNDS
VIBRATIONAL STATES