Coupling of torsion and OH-stretching in tert-butyl hydroperoxide. II. The OH-stretching fundamental and overtone spectra
| Autor: | Alexander Kjærsgaard, Casper V. Jensen, Anne B. McCoy, Emil Vogt, Henrik G. Kjaergaard, Anne S. Hansen, Rachel M. Huchmala, Jens Wallberg, Mark Boyer, Marsha I. Lester |
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| Rok vydání: | 2021 |
| Předmět: |
Torsional vibration
Materials science 010304 chemical physics Infrared Overtone Transition dipole moment General Physics and Astronomy Torsion (mechanics) 010402 general chemistry 01 natural sciences Molecular physics Spectral line 0104 chemical sciences symbols.namesake Fourier transform 0103 physical sciences symbols Physics::Chemical Physics Physical and Theoretical Chemistry Spectroscopy |
| Zdroj: | Vogt, E, Huchmala, R M, Jensen, C V, Boyer, M A, Wallberg, J, Hansen, A S, Kjærsgaard, A, Lester, M I, Mccoy, A B & Kjaergaard, H G 2021, ' Coupling of torsion and OH-stretching in tert-butyl hydroperoxide. II. The OH-stretching fundamental and overtone spectra ', The Journal of Chemical Physics, vol. 154, no. 16, 164307 . https://doi.org/10.1063/5.0048022 |
| ISSN: | 1089-7690 |
| Popis: | The vibrational spectra of gas phase tert-butyl hydroperoxide have been recorded in the OH-stretching fundamental and overtone regions (ΔvOH = 1–5) at room temperature using conventional Fourier transform infrared (ΔvOH = 1–3) and cavity ring-down (ΔvOH = 4–5) spectroscopy. In hydroperoxides, the OH-stretching and COOH torsion vibrations are strongly coupled. The double-well nature of the COOH torsion potential leads to tunneling splitting of the energy levels and, combined with the low frequency of the torsional vibration, results in spectra in the OH-stretching regions with multiple vibrational transitions. In each of the OH-stretching regions, both an OH-stretching and a stretch–torsion combination feature are observed, and we show direct evidence for the tunneling splitting in the OH-stretching fundamental region. We have developed two complementary vibrational models to describe the spectra of the OH-stretching regions, a reaction path model and a reduced dimensional local mode model, both of which describe the features of the vibrational spectra well. We also explore the torsional dependence of the OH-stretching transition dipole moment and show that a Franck–Condon treatment fails to capture the intensity in the region of the stretch–torsion combination features. The accuracy of the Franck–Condon treatment of these features improves with increasing ΔvOH. |
| Databáze: | OpenAIRE |
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