Cyclohexane Vibrations: High Resolution Spectra And Anharmonic Local Mode Calculations

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https://hdl.handle.net/2142/111115

Title: Cyclohexane Vibrations: High Resolution Spectra And Anharmonic Local Mode Calculations
Author(s): Bernath, Peter F.
Contributor(s): Sibert, Edwin
Issue Date: 2021-06-24
Keyword(s): Rotational structure/frequencies
Abstract: High resolution infrared absorption spectra of cyclohexane (C$_6$H$_{12}$) have been recorded from 1100 to 4000 cm$^{-1}$ at room temperature and 241 K. Cyclohexane is an oblate symmetric top with $D_{3d}$ symmetry. A rotational analysis was obtained for the $\nu_{27}$ (e$_{\rm{u}}$) and $\nu_{14}$ (a$_{\rm{2u}}$) CH$_2$ scissor modes at 1452.9 cm$^{-1}$ and 1456.4 cm$^{-1}$, respectively. Several combination modes were also assigned and rotationally analyzed. The C-H stretching modes are perturbed by overtone and combination modes of the CH$_2$ scissor vibrations, and an anharmonic local mode calculation was needed to interpret the spectra. The 4 main strong allowed C-H stretching modes appear as two e$_{\rm{u}}$ a$_{\rm{2u}}$ pairs near at 2862 cm$^{-1}$ and 2933 cm$^{-1}$. The Fermi-resonance local mode model coupling terms give physical insight into the effects that organize the cyclohexane vibrational energy levels. The unstrained cyclohexane molecule is a useful paradigm for six-membered rings in larger chemical and biological systems.
Publisher: International Symposium on Molecular Spectroscopy
Type of Resource: Text
Language: eng
Permalink: http://hdl.handle.net/2142/111115
DOI: 10.15278/isms.2021.RA07