Berlin 2014 – scientific programme
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MO: Fachverband Molekülphysik
MO 19: Femtosecond Spectroscopy 2
MO 19.7: Talk
Thursday, March 20, 2014, 18:00–18:15, BEBEL HS213
Impact of Different Hydrogen Bond Sites on the Molecular Network of Ionic Liquids from Ultrafast CARS Spectroscopy — •Susana Chatzipapadopoulos1, Matthias Lütgens1, Frank Friedriszik1, Tobias Zentel1, Daniela Kerlé2, Oliver Kühn1, Ralf Ludwig2, and Stefan Lochbrunner1 — 1Institut für Physik, Universität Rostock, Germany — 2Institut für Chemie, Universität Rostock, Germany
Ionic liquids (ILs) have unique properties which depend critically on the interaction between the ions. Understanding the intermolecular forces might enable an application-oriented tuning of their macroscopic properties. Here we study different imidazolium based ILs of the type [TeMIM][NTf2] with femtosecond multiplex CARS. Dephasing times and vibrational resonance frequencies are extracted by quantitative modeling of the complete CARS response. In previous investigations on a similar system of the type [CnMIM][NTf2] we found a hydrogen bond network formed by the three hydrogen atoms of the imidazolium ring [1]. In the present study we modified the ILs and replaced two hydrogens by methyl groups. In this way a simplified network with only one hydrogen bond per cation results and the bond position can be varied. From the frequencies of the isolated resonances an unambiguous assignment of the hydrogen bonds in the complete network with three hydrogen donors per cation is established. Spectral shifts and changes in dephasing times are discussed with respect to differences between the complete and the simplified hydrogen bond network.
[1] C. Roth et al., New J. Physics 14 (2012), 105026.