Multiresonant Coherent Multidimensional Spectroscopy of the Vibrationally Induced Decarboxylation of AOT: Deuterium Oxide Reverse Micelles

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• 作者：Samuel B. Penwell ; John C. Wright
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：May 12, 2011
• 年：2011
• 卷：115
• 期：18
• 页码：5564-5573
• 全文大小：1117K
• 年卷期：v.115,no.18(May 12, 2011)
• ISSN：1520-5207

文摘

The multiresonant coherent multidimensional spectroscopy study of D₂O in AOT micelles reveals two unexpected features in addition to those expected for D₂O. These features appear when the excitation pulse time ordering defines either fully coherent Liouville pathways or partially coherent pathways where there are intermediate populations. The features shift as the excitation pulse ordering changes between the two sets of pathways. They are attributed to the asymmetric stretch mode of CO₂ that is formed by the infrared excited decarboxylation of AOT. The cross-peaks鈥?intensity is enhanced when the excitation pulse is resonant with the CO₂ P and R branches for the fully coherent pathways, but they are depressed at the P and R branch resonances for the partially coherent pathways. The enhancement is attributed to the simultaneous production of CO₂ during the first excitation pulse when it is resonant with both the CO₂ and the D₂O. The depression is attributed to the absorption of the last excitation pulse by the CO₂ produced by the previous two excitation pulses. We believe that the decarboxylation occurs because of energy transfer from multiply excited D₂O molecules. It may cause a Norrish type I 伪-cleavage in the AOT that is followed by a Hunsdiecker reaction 尾-scission of the radical to form the CO₂. This experiment demonstrates the marriage of infrared induced chemistry and multiresonant coherent multidimensional spectroscopy into a single nonlinear process.