RENNERTELLER VIBRONIC ANALYIS OF THE GROUND STATE ENERGY
RENNER-TELLER VIBRONIC ANALYIS OF THE GROUND STATE ENERGY LEVELS OF THE HCCS FREE RADICAL Dennis J. Clouthier & Sheng-Gui He Department of Chemistry University of Kentucky Lexington, KY 40506 -0055
Electronic Spectroscopy of HCCS Excited State Electron configuration ( 2 3 4) 2 1/2 2 3/2 HCCS 417 -377 nm Ground State Electron configuration ( 2 4 3) 2 1/2 2 3/2
Bending Modes 4 H-C-C Bend 5 C-C-S Bend
Excited State of HCCS ØThe LIF spectra of HCCS & DCCS can be assigned if the 4 Renner-Teller effect is assumed to be very large. ØThis assumption also explains the different spinorbit splittings of the two isotopomers. ØHCCS is quasilinear in the excited state. S. -G. He & D. J. Clouthier, J. Chem. Phys. 120, 8544 (2004).
Pulsed Discharge Jet Apparatus Precursor & Argon
LIF Spectrum of HCCS
Vibronic Energy Levels of HCCS
HCCS Emission Spectra
HCCS Fluorescence Depletion Spectrum
DCCS Emission Spectra Br
DCCS Selective LIF Spectrum
Sears Resonances in HCCS
Theory H = H 0 + Hev + Hanh Includes Renner-Teller, spin-orbit, anharmonic, and Fermi resonance terms. Renner-Teller: 4, 5, & 45 terms. Anharmonic: usual terms plus new vibrational angular momentum coupling terms h 1 - h 4. Fermi resonance: W 1(344), W 2(344) etc.
Major Fitted Constants Parameter HCCS Experiment DCCS Ab Initio Experiment Ab Initio 1 2 781. 65(447) 780 755. 37(309) --- 523. 26(234) 579 416. 15(155) 471 3 355. 13(198) 374 326. 12(205) 343 A -276. 56(138) -261 -275. 99(66) -261 4 5 45 0. 4000(35) 0. 3287 0. 4194(32) 0. 3128 -0. 102(10) -0. 1330 -0. 1337(45) -0. 1171 0. 0997(35) 0. 0619 0. 0977(45) -0. 1046
ØEmission spectra analyzed and assigned. ØHamiltonian and matrix elements derived. ØHCCS/DCCS spectra fitted. ØRenner-Teller, spin-orbit coupling, anharmonic, and Fermi resonance parameters determined. ØThe thioketyl radical spectrum is now understood.
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