Simulating the Formation of Sodium:Electron Tight-Contact Pairs: Watching the Solvation of Atoms in Liquids One Molecule at a Time
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- 作者：William J. Glover ; Ross E. Larsen ; Benjamin J. Schwartz
- 刊名：Journal of Physical Chemistry A
- 出版年：2011
- 出版时间：June 16, 2011
- 年：2011
- 卷：115
- 期：23
- 页码：5887-5894
- 全文大小：943K
- 年卷期：v.115,no.23(June 16, 2011)
- ISSN：1520-5215
文摘
The motions of solvent molecules during a chemical transformation often dictate both the dynamics and the outcome of solution-phase reactions. However, a microscopic picture of solvation dynamics is often obscured by the concerted motions of numerous solvent molecules that make up a condensed-phase environment. In this study, we use mixed quantum/classical molecular dynamics simulations to furnish the molecular details of the solvation dynamics that leads to the formation of a sodium cation-solvated electron contact pair, (Na+, e鈭?/sup>), in liquid tetrahydrofuran following electron photodetachment from sodide (Na鈭?/sup>). Our simulations reveal that the dominant solvent response is comprised of a series of discrete solvent molecular events that work sequentially to build up a shell of coordinating THF oxygen sites around the sodium cation end of the contact pair. With the solvent response described in terms of the sequential motion of single molecules, we are then able to compare the calculated transient absorption spectroscopy of the sodium species to experiment, providing a clear microscopic interpretation of ultrafast pump鈭抪robe experiments on this system. Our findings suggest that for solute鈭抯olvent interactions similar to the ones present in our study, the solvation dynamics is best understood as a series of kinetic events consisting of reactions between chemically distinct local structures in which key solvent molecules must be considered to be part of the identity of the reacting species.