Electric fields of ionic liquids (ILs) were investigated by vibrational Stark effect spectroscopy using ethyl thiocyanate as a probe molecule. It was found that the stretching vibration of C≡N in nonhydroxyl ILs originates exclusively from the intrinsic electric fields, which are on average 3.0 MV cm^-1 higher than those of molecular solvents. In contrast, in the case of hydroxyl functional ILs, hydrogen bonding as well as the electric field contribute to the IR shift of C≡N.

★★★☆☆ Zhang SG,Zhang Y,Deng YQ. Investigation Of The Intrinsic Electric Field Of Nonhydroxyl And Hydroxyl Ionic Liquids By Vibrational Stark Effect Spectroscopy[J]. Rsc Advances,2013,3:11480-11484.