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Title: Lowest triplet (n,π{sup *}) state of 2-cyclohexen-1-one: Characterization by cavity ringdown spectroscopy and quantum-chemical calculations

Abstract

The cavity ringdown (CRD) absorption spectrum of 2-cyclohexen-1-one (2CHO) was recorded over the range 401.5–410.5 nm in a room-temperature gas cell. The very weak band system (ε ⩽ 0.1 M{sup −1} cm{sup −1}) in this spectral region is due to the T{sub 1}(n, π*) ← S{sub 0} electronic transition. The 0{sub 0}{sup 0} origin band was assigned to the feature observed at 24 558.8 ± 0.3 cm{sup −1}. We have assigned 46 vibronic transitions in a region extending from −200 to +350 cm{sup −1} relative to the origin band. For the majority of these transitions, we have made corresponding assignments in the spectrum of the deuterated derivative 2CHO-2,6,6-d{sub 3}. From the assignments, we determined fundamental frequencies for several vibrational modes in the T{sub 1}(n, π{sup *}) excited state of 2CHO, including the lowest ring-twisting (99.6 cm{sup −1}) and ring-bending (262.2 cm{sup −1}) modes. These values compare to fundamentals of 122.2 cm{sup −1} and 251.9 cm{sup −1}, respectively, determined previously for the isoconfigurational S{sub 1}(n, π{sup *}) excited state of 2CHO and 99 cm{sup −1} and 248 cm{sup −1}, respectively, for the S{sub 0} ground state. With the aid of quantum-mechanical calculations, we have also ascertained descriptions for these two modes, thereby resolving ambiguitiesmore » appearing in the previous literature. The ring-twisting mode (ν{sub 39}) contains a significant contribution from O=C–C=C torsion, whereas the ring-bending mode (ν{sub 38} in the ground state) involves mainly the motion of C-5 with respect to the plane containing the other heavy atoms. The CRD spectroscopic data for the T{sub 1}(n, π{sup *}) state have allowed us to benchmark several computational methods for treating excited states, including time-dependent density functional theory and an equation-of-motion coupled cluster method. In turn, the computational results provide an explanation for observed differences in the T{sub 1}(n, π{sup *}) vs. S{sub 1}(n, π{sup *}) ring frequencies.« less

Authors:
; ; ; ; ;  [1]
  1. Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54702-4004 (United States)
Publication Date:
OSTI Identifier:
22251271
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 139; Journal Issue: 21; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTRA; DENSITY FUNCTIONAL METHOD; EQUATIONS OF MOTION; EXCITED STATES; SPECTROSCOPY; TIME DEPENDENCE

Citation Formats

McAnally, Michael O., Zabronsky, Katherine L., Stupca, Daniel J., Phillipson, Kaitlyn, Pillsbury, Nathan R., and Drucker, Stephen. Lowest triplet (n,π{sup *}) state of 2-cyclohexen-1-one: Characterization by cavity ringdown spectroscopy and quantum-chemical calculations. United States: N. p., 2013. Web. doi:10.1063/1.4834655.
McAnally, Michael O., Zabronsky, Katherine L., Stupca, Daniel J., Phillipson, Kaitlyn, Pillsbury, Nathan R., & Drucker, Stephen. Lowest triplet (n,π{sup *}) state of 2-cyclohexen-1-one: Characterization by cavity ringdown spectroscopy and quantum-chemical calculations. United States. https://doi.org/10.1063/1.4834655
McAnally, Michael O., Zabronsky, Katherine L., Stupca, Daniel J., Phillipson, Kaitlyn, Pillsbury, Nathan R., and Drucker, Stephen. 2013. "Lowest triplet (n,π{sup *}) state of 2-cyclohexen-1-one: Characterization by cavity ringdown spectroscopy and quantum-chemical calculations". United States. https://doi.org/10.1063/1.4834655.
@article{osti_22251271,
title = {Lowest triplet (n,π{sup *}) state of 2-cyclohexen-1-one: Characterization by cavity ringdown spectroscopy and quantum-chemical calculations},
author = {McAnally, Michael O. and Zabronsky, Katherine L. and Stupca, Daniel J. and Phillipson, Kaitlyn and Pillsbury, Nathan R. and Drucker, Stephen},
abstractNote = {The cavity ringdown (CRD) absorption spectrum of 2-cyclohexen-1-one (2CHO) was recorded over the range 401.5–410.5 nm in a room-temperature gas cell. The very weak band system (ε ⩽ 0.1 M{sup −1} cm{sup −1}) in this spectral region is due to the T{sub 1}(n, π*) ← S{sub 0} electronic transition. The 0{sub 0}{sup 0} origin band was assigned to the feature observed at 24 558.8 ± 0.3 cm{sup −1}. We have assigned 46 vibronic transitions in a region extending from −200 to +350 cm{sup −1} relative to the origin band. For the majority of these transitions, we have made corresponding assignments in the spectrum of the deuterated derivative 2CHO-2,6,6-d{sub 3}. From the assignments, we determined fundamental frequencies for several vibrational modes in the T{sub 1}(n, π{sup *}) excited state of 2CHO, including the lowest ring-twisting (99.6 cm{sup −1}) and ring-bending (262.2 cm{sup −1}) modes. These values compare to fundamentals of 122.2 cm{sup −1} and 251.9 cm{sup −1}, respectively, determined previously for the isoconfigurational S{sub 1}(n, π{sup *}) excited state of 2CHO and 99 cm{sup −1} and 248 cm{sup −1}, respectively, for the S{sub 0} ground state. With the aid of quantum-mechanical calculations, we have also ascertained descriptions for these two modes, thereby resolving ambiguities appearing in the previous literature. The ring-twisting mode (ν{sub 39}) contains a significant contribution from O=C–C=C torsion, whereas the ring-bending mode (ν{sub 38} in the ground state) involves mainly the motion of C-5 with respect to the plane containing the other heavy atoms. The CRD spectroscopic data for the T{sub 1}(n, π{sup *}) state have allowed us to benchmark several computational methods for treating excited states, including time-dependent density functional theory and an equation-of-motion coupled cluster method. In turn, the computational results provide an explanation for observed differences in the T{sub 1}(n, π{sup *}) vs. S{sub 1}(n, π{sup *}) ring frequencies.},
doi = {10.1063/1.4834655},
url = {https://www.osti.gov/biblio/22251271}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 21,
volume = 139,
place = {United States},
year = {Sat Dec 07 00:00:00 EST 2013},
month = {Sat Dec 07 00:00:00 EST 2013}
}