論文

2009年8月

Stretch-bend combination polyads in the (A)over-tilde(1)A(u) state of acetylene, C2H2

JOURNAL OF MOLECULAR SPECTROSCOPY
  • Adam H. Steeves
  • ,
  • Hans A. Bechtel
  • ,
  • Anthony J. Merer
  • ,
  • Nami Yamakita
  • ,
  • Soji Tsuchiya
  • ,
  • Robert W. Field

256
2
開始ページ
256
終了ページ
278
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1016/j.jms.2009.05.005
出版者・発行元
ACADEMIC PRESS INC ELSEVIER SCIENCE

Rotational analyses are reported for a number of newly-discovered vibrational levels of the SI-trans; ((A) over tilde (1)A(u)) state of C2H2. These levels are combinations where the Franck-Condon active nu(2)' and nu(3)' vibrational modes are excited together with the low-lying bending vibrations, nu(4)' and nu(6)'. The structures of the bands are complicated by strong a- and b-axis Coriolis coupling, as well as Darling-Dennison resonance for those bands that involve overtones of the bending vibrations. The most interesting result is the strong anharmonicity in the combinations of nu(3)' (trans bend, a(g)) and nu(6)' (in-plane cis bend, b(u)). This anharmonicity presumably represents the approach of the molecule to the trans-cis isomerization barrier, where ab initio results have predicted the transition state to be half-linear, corresponding to simultaneous excitation of nu(3)' and nu(6)'. The anharmonicity also causes difficulty in the least squares fitting of some of the polyads, because the simple model of Coriolis coupling and Darling-Dennison resonance starts to break down. The effective Darling-Dennison parameter, K-4466, is found to increase rapidly with excitation of nu(3)', while many small centrifugal distortion terms have had to be included in the least squares fits in order to reproduce the rotational structure correctly. Fermi resonances become important where the K-structures of different polyads overlap, as happens with the 2(1)3(1)B(1) and 3(1)B(3) polyads (B = 4 or 6). The aim of this work is to establish the detailed vibrational level structure of the S-1-trans state in order to search for possible S-1-cis ((1)A(2)) levels. This work, along with results from other workers, identifies at least one K sub-level of every single vibrational level expected up to a vibrational energy of 3500 cm(-1). (C) 2009 Elsevier Inc. All rights reserved.

Web of Science ® 被引用回数 : 21

リンク情報
DOI
https://doi.org/10.1016/j.jms.2009.05.005
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000268599300013&DestApp=WOS_CPL
ID情報
  • DOI : 10.1016/j.jms.2009.05.005
  • ISSN : 0022-2852
  • Web of Science ID : WOS:000268599300013

エクスポート
BibTeX RIS