Origins of Spectral Broadening in Iodated Vaska鈥檚 Complex in Binary Solvent Mixtures
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- 作者：Brynna H. Jones ; Aaron M. Massari
- 刊名：Journal of Physical Chemistry B
- 出版年：2013
- 出版时间：December 12, 2013
- 年：2013
- 卷：117
- 期：49
- 页码：15741-15749
- 全文大小：360K
- 年卷期：v.117,no.49(December 12, 2013)
- ISSN：1520-5207
文摘
Linear absorption spectroscopy of the iridium-bound carbonyl on an iodated adduct of Vaska鈥檚 complex has shown that the mean vibrational frequency is insensitive to solvation by a broad range of solvents, while the spectral line width changes significantly. The spectral broadening is more significant in chloroform than benzyl alcohol, which is puzzling considering that benzyl alcohol is more polar. In this study, 2D-IR spectroscopy was performed on this vibrational mode to dissect the linear line shape into its homogeneous and inhomogeneous contributions in binary solvent mixtures of either chloroform or benzyl alcohol in d6-benzene. The full frequency鈥揻requency correlation function was determined, including the homogeneous line width and fast spectral diffusion. We find that the frequency fluctuation magnitudes show the most notable changes in chloroform mixtures, while the time constants for spectral diffusion change more dramatically in benzyl alcohol mixtures. Nonetheless, we conclude that the frequency fluctuation magnitudes in both solvent mixtures most clearly explain the differences in their linear line widths. The homogeneous contributions were found to either stay the same or decrease as the more polar solvent was added to d6-benzene, thereby implicating inhomogeneous dynamics as the dominant broadening mechanism.