J. Phys. Chem. A, 108 (15), 2993 -2998, 2004. 10.1021/jp0373696 S1089-5639(03)07369-9
Web Release Date: February 4, 2004

Copyright © 2004 American Chemical Society

Ion Emission from Water Ice Due to Energetic Particle Bombardment

Igor A. Wojciechowski, Shixin Sun, Christopher Szakal, Nicholas Winograd, and Barbara J. Garrison*

Department of Chemistry, 152 Davey Laboratory, Materials Research Institute, 184 MRI Building, Penn State University, University Park, Pennsylvania 16802

Received: November 5, 2003

In Final Form: December 20, 2003

Abstract:

Ion emission from water ice due to energetic particle bombardment is investigated in a combined molecular dynamics and tof-SIMS experimental study. Specifically, emission of water clusters A±(H2O)n, where A± denotes positive alkali metal ions, Li+, Na+, K+, Cs+ or negative halogen ions, F-, Cl-, I-, from frozen ice films is investigated. In the experiments, different concentrations of NaI and KI salts were dissolved in water before freezing. The influence of ion charge and concentration is investigated. Cationic clusters eject more effectively than anionic clusters in both the simulations and experiments. Although in most cases the increase of the salt concentration results in a higher absolute ion yield, this dependence is rather complex and is discussed in terms of ion pairing and clustering in the original solution and during emission.

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