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-3methylimidazolium 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 1Ethyl-3-methylimidazolium based ionic liquids. Surprisingly 1-Ethyl-3-methylimidazolium or 1-Ethyl-2methylimidazolium cations were not detected in the [EMMIM][TFSI] fragmentation pattern. (c) 2021 Published by Elsevier B.V.

Automated summary

The experiment explores the fragmentation patterns of different ionic liquids under VUV excitation, showing that ILs with larger anions exhibit reduced cation fragmentation. [EMMIM][TFSI] was studied for the first time, revealing unique decomposition products compared to other similar ILs. Surprisingly, certain cations were not detected in the fragmentation pattern of [EMMIM][TFSI].