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Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

Ultraviolet Laser Irradiation of Low Concentration Liquid Microjets: Solute Evaporation and Solvent Initiated Reactivity

Wendy L. Holstein, Laura M. Dobeck, Dale E. Otten, Gregory F. Metha and Mark A. Buntine

Australian Journal of Chemistry 56(5) 481 - 487
Published: 20 May 2003

Abstract

Resonance-enhanced 266 nm 1 + 1 multiphoton ionization has been used in conjunction with a liquid microjet time-of-flight mass spectrometer to explore the photochemistry of a 10–3 M solution of anisole in ethanol. Only ions generated in the condensed phase originating from the three-photon non-resonant ionization of the ethanol solvent are liberated into the vacuum. No solute ions generated in solution are observed unless the concentration is increased to 1 M. Under high concentration conditions, solute pairing or aggregation at the liquid surface is a necessary precursor towards liberating solute photoions into the vacuum via a Coulombic explosion. At a solution concentration of 10–3 M, a decreased solute ion density at the liquid surface is insufficient to initiate a Coulombic explosion into the vacuum. Rather, non-resonantly generated solvent ions on the liquid surface dominate the ion ejection process. Related studies on 10–3 M solutions of 4-methoxyphenol in both ethanol and water show that at this concentration solute ionization is most likely to be observed following thermal evaporation from the surface of a liquid beam.

https://doi.org/10.1071/CH03011

© CSIRO 2003

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