Laser-enhanced electron ionisation

Enhanced molecular ion implies reduced matrix interference. An SMB-El mass spectrum usually provides information comparable to field ionisation, but fragmentation can be promoted through increase of the electron energy. For many compounds the sensitivity of HSI can be up to 100 times that of El. Aromatics are ionised with a much greater efficiency than saturated compounds. Supersonic molecular beams are used in mass spectrometry in conjunction with GC-MS [44], LC-MS [45] and laser-induced multiphoton ionisation followed by time-of-flight analysis [46]. 

Laser-enhanced ionisation spectroscopy (LEIS) is essentially a very sensitive mono-element analysis method (as AFS or AAS) with limits of detection (LCDs) often in the 1-100 pgmL range [96,97]. LEIS is based on the measurement of the increase in ionisation of the analyte in a flame, furnace, or glow discharge by laser irradiation as a result of selective population of a level of the term diagram. In LEIS, one or two dye lasers are tuned to a wavelength characteristic of an electronic transition of the species of interest. The laser beam(s) are directed... 

---