Intermolecular interactions in ionic liquids studied by THz, far IR and Raman spectroscopy

• Applicant: Professor Dr. Ralf Ludwig
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2008 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 92218760

The unusual properties of ionic liquids (ILs) are governed by the type and strength of interaction between its constituents. Intermolecular forces between cation and anion determine whether expanded network structures, larger aggregates or ion-pairs are found in this new liquid material. The strength of interaction is given by an interplay between different intermolecular forces. In this project these different types of forces will be studied by THz, far IR and Raman spectroscopy. All methods probe the lowfrequency vibrational modes which can be directly related to the intermolecular forces between cation and anion in aprotic and protic ionic liquids. A better understanding of hydrogen bonding, aggregation and proton transfer enables to tune the favored properties in these Coulomb systems. Probing the cation-anion interaction also opens a new path for developing new force fields used in molecular dynamics and Monte Carlo simulations. This is in particular true for protic ionic liquids (PILs), where the force field development is still in its infancy.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1191: Ionic Liquids