Ion fragmentation study of [EMMIM][TFSI], [EMIM][OTf] and [EMIM][DCA] by vacuum ultraviolet light

The ionic liquids (ILs) 1-Ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [EMMIM][TFSI], 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate [EMIM][OTf] and 1-Ethyl-3-methylimidazolium dicyanamide [EMIM][DCA] were evaporated by effusion and a time-of-flight (TOF) instrument was employed as the mass analyzer while vacuum ultraviolet (VUV) light in the energy range 9–20 eV was used to excite the IL molecules. Fragmentation patterns with respect to excitation energy are discussed and decomposition products are analyzed. Hydrogenated and dehydrogenated fragments are discussed. Our experiment seems to show that the ionic liquids with larger anions have less cation fragmentation. [EMMIM][TFSI] was studied for the first time and it produces different fragments than 1-Ethyl-3-methylimidazolium based ionic liquids. Surprisingly 1-Ethyl-3-methylimidazolium or 1-Ethyl-2-methylimidazolium cations were not detected in the [EMMIM][TFSI] fragmentation pattern.