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STEVEN D. FLYNN, GARY E. DOUBERLY, Department of Chemistry, University of Georgia, Athens, Georgia, USA 30602.
The Infrared spectrum of the vapor produced upon thermal vaporization of the [emim][Tf2N] ionic liquid has been obtained using the helium nanodroplet isolation method. Despite the low vapor pressure of [emim][Tf2N], sufficient gas phase densities are produced, allowing for efficient helium nanodroplet pick-up. The mass spectrum of the emim[Tf2N] doped droplet beam shows signatures\footnoteArmstrong, J.P.; Hurst, C.; Jones, R. G.; Licence, P.; Lovelock, K. R. J.; Satterley, C. J.; Villar-Garcia, I. J. Physical Chemistry Chemical Physics \textbf2007, 9 , 982.
Strasser, D.; Goulay, F.; Belau, L.; Kostko, O.; Koh, C.; Chambreau, S. D.; Vaghjiani, G. L.; Ahmed, M.; Leone, S. R. textitJournal of Physical Chemistry A \textbf2010, textit114, 879. that have been attributed in gas phase measurements to the presence of isolated, intact [emim][Tf2N] ion-pairs. Furthermore, the mass spectrometry results indicate that emim[Tf2N] does not undergo thermal decomposition at 410 K. Comparisons are made between the experimental measurements and ab initio calculations (mp2/6-311++g(d,p)) of the CH stretch vibrational bands and permanent electric dipole moments for several [emim][Tf2N] low energy isomers. The helium nanodroplet infrared spectrum of this species provides rather definitive support to the previously suggested vaporization mechanism of ionic liquids.\footnoteStrasser, D.; Goulay, F.; Kelkar, M. S.; Maginn, E. J.; Leone, S. R. Journal of Physical Chemistry A \textbf2007, 111 , 3191.
Chambreau, S. D.; Vaghjiani, G. L.; To, A.; Koh, C.; Strasser, D.; Kostko, O.; Leone, S. R. Journal of Physical Chemistry B \textbf2010, 114, 1361.
Maginn, E. J.; Kelkar, M. S. Journal of Physical Chemistry B \textbf2007, 111 , 9424.