Vibrational Overtone Spectroscopy and Intramolecular Dynamics of Ethene

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• 作者：Alexander Portnov ; Evgeny Bespechansky ; Ilana Bar
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：October 25, 2007
• 年：2007
• 卷：111
• 期：42
• 页码：10646 - 10653
• 全文大小：137K
• 年卷期：v.111,no.42(October 25, 2007)
• ISSN：1520-5215

文摘

The first through fourth C-H stretching overtone regions of ethene were measured by photoacousticspectroscopy of room-temperature molecules and action spectroscopy of jet-cooled molecules. The rotationalcooling led to improved resolution in the action spectra, turning these spectra into key players in determiningthe multiple band appearance in each region, their types, and origins. These manifolds arise from strongcouplings of the C-H stretches to doorway states and were analyzed in terms of a simplified joint local-mode/normal-mode (LM)/(NM) model and an equivalent NM model, accounting for principal resonances.The diagonalization of the LM/NM and NM vibrational Hamiltonians and the least-square fittings revealedmodel parameters, enabling assignment of A- and B-type bands. These bands behave differently through theV = 2-4 manifolds, showing coupling to doorway states for the former but not for the latter. The energyflow out of the fourth C-H overtone is governed by the interaction with bath states due to the increase in thedensity of states.