O3.2 - Detection of Aromatic/Aliphatic Hydrocarbons and Amines by Laser-Ion Mobility Spectrometry (LIMS)

Trace detection of hydrocarbons has been investigated using a laser ion mobility spectrometer (LIMS). The LIMS instrument used employs resonant two-photon ionization as a mechanism for the generation of analyte gas ions. We find that LIMS easily ionizes aromatic and aliphatic hydrocarbons with conjugated and delocalized C-C double bond systems. Another class of organic compounds that could be successfully detected was amines. These latter substances contain double-occupied lone pair electrons localized on basic N atoms. All substances successfully detected feature a sizeable UV absorption within a certain range of photon energies Eph. Two-photon ionization is observed in case the molecule-specific ionization energy EI complies with the energetic condition 2Eph >E I.