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Titolo:
The infrared-ultraviolet dispersed fluorescence spectrum of acetylene: Newclasses of bright states
Autore:
Hoshina, K; Iwasaki, A; Yamanouchi, K; Jacobson, MP; Field, RW;
Indirizzi:
Univ Tokyo, Sch Sci, Dept Chem, Bunkyo Ku, Tokyo 1130033, Japan Univ Tokyo Tokyo Japan 1130033 ept Chem, Bunkyo Ku, Tokyo 1130033, Japan MIT, Dept Chem, Cambridge, MA 02139 USA MIT Cambridge MA USA 02139MIT, Dept Chem, Cambridge, MA 02139 USA MIT, George R Harrison Spect Lab, Cambridge, MA 02139 USA MIT Cambridge MA USA 02139 R Harrison Spect Lab, Cambridge, MA 02139 USA
Titolo Testata:
JOURNAL OF CHEMICAL PHYSICS
fascicolo: 17, volume: 114, anno: 2001,
pagine: 7424 - 7442
SICI:
0021-9606(20010501)114:17<7424:TIDFSO>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
INTRAMOLECULAR VIBRATIONAL REDISTRIBUTION; DOUBLE-RESONANCE SPECTROSCOPY; HIGHLY EXCITED ACETYLENE; ENERGY-LEVELS; PARTIAL DEPERTURBATION; ABSORPTION-SPECTRUM; INTERNAL ENERGY; C2H2; CONSTANTS; PATTERN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
46
Recensione:
Indirizzi per estratti:
Indirizzo: Yamanouchi, K Univ Tokyo, Sch Sci, Dept Chem, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan Univ Tokyo 7-3-1 Hongo Tokyo Japan 1130033 o 1130033, Japan
Citazione:
K. Hoshina et al., "The infrared-ultraviolet dispersed fluorescence spectrum of acetylene: Newclasses of bright states", J CHEM PHYS, 114(17), 2001, pp. 7424-7442

Abstract

Single rotational levels of ungerade vibrational levels, 2 nu (3)'+nu (6)'and 3 nu (3)'+nu (6)' (both with b(u) symmetry), in the (A) over tilde (1)A(u) electronically excited state of acetylene were excited by an IR-UV double resonance scheme via the nu (3)" fundamental level in the (X) over tilde (1)Sigma (+)(g) state, and the rotationally resolved dispersed fluorescence (DF) spectra were recorded at 3.2-4.5 cm(-1) resolution. The term valuesof the new ungerade levels were determined within an accuracy of 0.56 cm(-1)(1 sigma) through careful calibration achieved by frequency standard atomic Fe and Hg lines. A total of 111 new ungerade vibrational levels with Sigma (+)(u), Sigma (-)(u), and Delta (u) symmetry below 10 000 cm(-1) was identified in the high-resolution IR-UV-DF spectra, which provide access to new classes of (X) over tilde (1)Sigma (+)(g) bright states: (i) (0,upsilon (2)" ,0,upsilon (4)" (1),1(-1))Sigma (+)(u), (0,upsilon (2)" ,0,upsilon (4)"(1),1(1))Delta (u), and (0,upsilon (2)" ,0,upsilon (4)" (3),1(-1))Delta (u), which are the Franck-Condon (FC) bright levels from the n nu (3)' + nu (6)' (n=2,3) levels in the (A) over tilde (1)A(u) state; (ii) (0,upsilon (2)" ,0,upsilon (4)" (-1),1(1))Sigma (-)(u) levels which appear through the a-axis Corioris interaction between n nu (3)' + nu (6)' and n nu (3)' + nu (4)' (n=2,3) in the A (1)A(u) state; and (iii) (0,upsilon (2)" ,1,upsilon (4)" (0),0)Sigma (+)(u) and (0,upsilon (2)" ,1,upsilon (4)" (2),0)Delta (u) levels which gain transition intensity from the Duschinsky effect associated with the bent-linear (A) over tilde-(X) over tilde transition. All observedungerade term values and previously determined gerade and ungerade term values below 10 000 cm(-1) were fitted by two effective model Hamiltonians, i.e., a pure-bend effective Hamiltonian and a stretch-bend effective Hamiltonian. The stretch-bend effective Hamiltonian is expressed in terms of 31 Dunham expansion parameters and 11 anharmonic resonance parameters associatedwith (i) five stretch-bend anharmonic resonances; (ii) one stretch-stretchand two bend-bend Darling-Dennison resonances; and (iii) one vibrational lresonance. The parameters in this Hamiltonian were determined from a least-squares fit of 287 vibrational term values (111 new ungerade levels, 128 levels from absorption, 1 level from stimulated Raman, 13 levels from stimulated emission pumping (SEP), and 34 levels from UV-DF spectroscopy) below 10 000 cm(-1) with a standard deviation of sigma = 1.21 cm(-1). The FC patterns for the v(4)" = odd ungerade levels, (0,v(2)" ,0,v(4)" ,1), in the IR-UV-DF spectra were derived, and the nodes along the v(4)' trans-bend mode were found at v(4)" = 11 via the 2 nu (3)' + nu (6)' upper state, and at v(4)" = 9 and 15 via the 3 nu (3)' + nu (6)' upper state, which is consistent with the nu (')(3) dependence of the FC patterns observed in previous UV-DF studies. (C) 2001 American Institute of Physics.

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Documento generato il 06/07/20 alle ore 03:35:08