Laser ablation of imidazolium based ionic liquids

Time-of-flight mass spectrometry has been used to investigate the IR ablation of several ionic liquid imidazolium salts of the form R(1)R(2)Iium X (R-1 = methyl; R-2 = methyl, ethyl, butyl, and hexyl; X = Cl-, NO3-, and CH3SO4-). The ablated ionic species were analyzed by time-of-flight mass spectrometry using pulsed extraction, and neutral species were detected using vacuum UV photoionization at 10.5 eV. The results demonstrate that at least 99% of the ablated material is removed in the form of nano- or microdroplets consisting of intact ionic liquid. Approximately 1% is ejected as imidazole molecules (R(1)R(2)Im) produced through the elimination of HCl, and about 0.1% of the material is ejected in the form of single salt molecules of R(1)R(2)Iium X. A chemical thermometer was used to measure the internal temperature (475 +/- 25 K) of the ablated vapor plume.