O–H Stretch Overtone Excitation of Ethyl Hydroperoxide Conformers
| Autor: | Shizuka Hsieh, Thida Thida, Kelly Smith, Noah Naamad, R. G. Linck, Margaret K. Nyamumbo |
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| Rok vydání: | 2011 |
| Předmět: |
Quantitative Biology::Biomolecules
Chemistry Overtone Ab initio Physics::Optics Photoacoustic imaging in biomedicine Laser Mathematics::Algebraic Topology Spectral line law.invention law Physical chemistry Ethyl hydroperoxide Physics::Atomic Physics Physics::Chemical Physics Physical and Theoretical Chemistry Conformational isomerism Excitation |
| Zdroj: | The Journal of Physical Chemistry A. 115:14040-14044 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp208467f |
| Popis: | We present laser photoacoustic spectra of ethyl hydroperoxide (EHP) for 3-6 quanta of O-H stretch. Spectra are consistent with ab initio spectral simulations that take into account the influence of torsional motion about the O-O bond on O-H stretch overtone excitation. Experimental and simulated spectra share two trends. First, spectral features due to torsional excitation, including hot bands, become more prominent with increasing O-H stretch excitation, as has been shown previously for similar molecules such as methyl hydroperoxide. Second, contributions from the two different EHP conformers become clearly distinguishable at higher O-H stretch excitation, mainly due to the role of torsional motion. Results are consistent with a higher energy separation (330 cm(-1)) between the lower energy anti and the higher energy gauche conformers than predicted by electronic structure calculations (137 cm(-1)). Calculated absorption intensities are consistently higher than experimental values by ~30% but within the experimental uncertainty. With each additional O-H stretch overtone, the dropoff in calculated integrated absorption intensities at room temperature becomes less extreme, with a 14-fold dropoff from 3ν(OH) to 4ν(OH) and an 8-fold decrease from 5ν(OH) to 6ν(OH). |
| Databáze: | OpenAIRE |
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