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Title: The à 1A u state of acetylene: ungerade vibrational levels in the region 45,800–46,550 cm -1

Abstract

The ungerade vibrational levels of the à 1A u (S 1-trans) state of C 2H 2 lying in the region 45,800-46,550 cm -1 have been assigned from IR-UV double resonance spectra. The aim has been to classify the complete manifold of S 1-trans levels in this region, so as to facilitate the assignment of the bands of S 1-cis C 2H 2. The rotational structure is complicated because of the overlapping of vibrational polyads with different Coriolis and Darling–Dennison parameters, but assignments have been possible with the help of predictions based on the properties of polyads at lower energy. An important result is that the analysis of the (1 14 1, 1 16 1) polyad determines the anharmonicity constants x14 and x16, which will be needed to proceed to higher energies. Some regions of impressive complexity occur. Among these is the band given by the 3 36 1, K=1 state at 45,945 cm -1, where a three-level interaction within the S 1 state is confused by triplet perturbations. Several probable S 1-cis states have been observed, including cis-6 2, K=1; this vibrational level appears to show a K-staggering, of the type that arises when quantum mechanical tunnelling through the barriermore » to cis-trans isomerization is possible. The total number of identified cis vibrational states is now 6 out of an expected 10 up to the energies discussed in this paper.« less

Authors:
 [1];  [1];  [2];  [1];  [1];  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Chemistry
  2. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, (Taiwan) ; Univ. of British Columbia, Vancouver, BC (Canada). Dept. of Chemistry
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1169176
Grant/Contract Number:  
FG02-87ER13671
Resource Type:
Accepted Manuscript
Journal Name:
Molecular Physics
Additional Journal Information:
Journal Volume: 110; Journal Issue: 21-22; Journal ID: ISSN 0026-8976
Publisher:
Taylor & Francis
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; acetylene; cis-trans isomerization; double resonance; spectroscopy; perturbations

Citation Formats

Baraban, Joshua H., Changala, P. Bryan, Merer, Anthony J., Steeves, Adam H., Bechtel, Hans A., and Field, Robert W. The à 1Au state of acetylene: ungerade vibrational levels in the region 45,800–46,550 cm-1. United States: N. p., 2012. Web. doi:10.1080/00268976.2012.706329.
Baraban, Joshua H., Changala, P. Bryan, Merer, Anthony J., Steeves, Adam H., Bechtel, Hans A., & Field, Robert W. The à 1Au state of acetylene: ungerade vibrational levels in the region 45,800–46,550 cm-1. United States. doi:10.1080/00268976.2012.706329.
Baraban, Joshua H., Changala, P. Bryan, Merer, Anthony J., Steeves, Adam H., Bechtel, Hans A., and Field, Robert W. Tue . "The à 1Au state of acetylene: ungerade vibrational levels in the region 45,800–46,550 cm-1". United States. doi:10.1080/00268976.2012.706329. https://www.osti.gov/servlets/purl/1169176.
@article{osti_1169176,
title = {The à 1Au state of acetylene: ungerade vibrational levels in the region 45,800–46,550 cm-1},
author = {Baraban, Joshua H. and Changala, P. Bryan and Merer, Anthony J. and Steeves, Adam H. and Bechtel, Hans A. and Field, Robert W.},
abstractNote = {The ungerade vibrational levels of the à 1Au (S1-trans) state of C2H2 lying in the region 45,800-46,550 cm-1 have been assigned from IR-UV double resonance spectra. The aim has been to classify the complete manifold of S1-trans levels in this region, so as to facilitate the assignment of the bands of S1-cis C2H2. The rotational structure is complicated because of the overlapping of vibrational polyads with different Coriolis and Darling–Dennison parameters, but assignments have been possible with the help of predictions based on the properties of polyads at lower energy. An important result is that the analysis of the (1141, 1161) polyad determines the anharmonicity constants x14 and x16, which will be needed to proceed to higher energies. Some regions of impressive complexity occur. Among these is the band given by the 3361, K=1 state at 45,945 cm-1, where a three-level interaction within the S1 state is confused by triplet perturbations. Several probable S1-cis states have been observed, including cis-62, K=1; this vibrational level appears to show a K-staggering, of the type that arises when quantum mechanical tunnelling through the barrier to cis-trans isomerization is possible. The total number of identified cis vibrational states is now 6 out of an expected 10 up to the energies discussed in this paper.},
doi = {10.1080/00268976.2012.706329},
journal = {Molecular Physics},
number = 21-22,
volume = 110,
place = {United States},
year = {2012},
month = {7}
}

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