Dynamics of Electrons in Ammonia Cages: The Discovery System of Solvation

Authors

  • I-Ren Lee,

    1. Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA, Fax: (+1) 626-796-8315.
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  • Wonchul Lee Dr.,

    1. Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA, Fax: (+1) 626-796-8315.
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  • Ahmed H. Zewail Prof.

    1. Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA, Fax: (+1) 626-796-8315.
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Abstract

Two centuries ago solvated electrons were discovered in liquid ammonia and a century later the concept of the solvent cage was introduced. Here, we report a real time study of the dynamics of size-selected clusters, n=20 to 60, of electrons in ammonia, and, for comparison, that of electrons in water cages. Unlike the water case, the observed dynamics for ammonia indicates the formation, through a 100 fs temperature jump, of a solvent collective motion in a 500 fs relaxation process. The agreement of the experimental results—obtained for a well-defined n, gated electron kinetic energy, and time delay—with molecular dynamics theory suggests the critical and different role of the kinetic energy and the librational motions involved in solvation.

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