We study the molecular rotation of the protic room-temperature ionic liquid ethylammonium nitrate with dielectric relaxation spectroscopy and femtosecond-infrared spectroscopy (fs-IR) of the ammonium N-H vibrations. The results suggest that the rotation of ethylammonium ion takes place via large angular jumps. Such nondiffusive reorientational dynamics is unique to strongly hydrogen-bonded liquids such as water and indicates that the intermolecular interaction is highly directional in this class of ionic liquids.

J. Phys. Chem. Lett.
Ultrafast Spectroscopy

Hunger, J., Sonnleitner, T., Liu, L., Buchner, R., Bonn, M., & Bakker, H. (2012). Hydrogen-bond dynamics in a protic ionic liquid : evidence of large-angle jumps. J. Phys. Chem. Lett., 3(20), 3034–3038. doi:10.1021/jz301334j