Rotational Energy Distributions of Benzene Liberated from Aqueous Liquid Microjets: A Comparison between Evaporation and Infrared Desorption

Olivia J. Maselli; Jason R. Gascooke; Sarah L. Kobelt; Gregory F. Metha; Mark A. Buntine

doi:10.1071/CH05319

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Rotational Energy Distributions of Benzene Liberated from Aqueous Liquid Microjets: A Comparison between Evaporation and Infrared Desorption

Olivia J. Maselli ^A , Jason R. Gascooke ^A , Sarah L. Kobelt ^A , Gregory F. Metha ^A and Mark A. Buntine ^A ^B

+ Author Affiliations

- Author Affiliations

^A Department of Chemistry, University of Adelaide, SA 5005, Australia.

^B Corresponding author. Email: mark.buntine@adelaide.edu.au

Australian Journal of Chemistry 59(2) 104-108 https://doi.org/10.1071/CH05319
Submitted: 21 November 2005 Accepted: 13 January 2006 Published: 7 March 2006

Abstract

We have measured the rotational energy distribution of benzene molecules both evaporated and desorbed by an IR laser from a liquid microjet. Analysis of the 6₀¹ vibronic band of benzene has shown that the benzene molecules evaporating from the liquid microjet surface have a rotational temperature of 157 ± 7 K. In contrast, the rotational temperature of benzene molecules desorbed from the liquid microjet by a 1.9 μm laser pulse is 82 ± 5 K. However, in both cases careful inspection of the spectral profiles shows that the experimental rotational distributions are non-Boltzmann, displaying an underpopulation of high rotational states and a relative overpopulation of the low rotational states. The non-equilibrium evaporation and desorption spectral profiles are consistent with a model that involves transfer of internal energy into translation upon liberation from the condensed phase.

Acknowledgments

Financial support provided by the Australian Research Council (ARC) and the University of Adelaide, technical assistance in apparatus construction by Mr P. Apoefis, and the assistance of Mr M. Shoji (University of Tokyo) in conducting some of the experiments are all gratefully acknowledged. We thank Professor W. D. Lawrance (Flinders University) for helpful discussions. O.J.M. acknowledges scholarship support in the form of an Australian Postgraduate Award.

References

Rotational Energy Distributions of Benzene Liberated from Aqueous Liquid Microjets: A Comparison between Evaporation and Infrared Desorption

Abstract

Acknowledgments

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