Engineering Physics Annotation << Back Laser Field Asymmetric Ion Mobility Spectrometer for Ultralow Concentrations of Nitro Compounds Detection G.E. Kotkovskiy, A.V. Tugaenko, A.A. Chistyakov The new method of substance analysis combining field asymmetric ion mobility spectrometry and atmosphere laser ionization is presented. The 4-th harmonic of pulse YAG: Nd3+ (? = 266 nm) laser radiation is used. The results of detection of nitro compounds: 2, 4, 6-trinitrotoluene (TNT) and Hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX) are presented. The dependence of ion peak position on humidity in the drift region is investigated. It is shown that background peak is shifted at humidity increase while nitro compounds peaks are stable. It is also shown that at high intensity of laser radiation (q ~ 107 W/cm2) the spectrum is similar to the spectra obtained from other sources of ionization. The set of reactant peaks is observed in this case. Opposite, at low intensity (q ~ 105 W/cm2) the spectrum free from background and reactant-peaks with unique peak of investigated substance (TNT) might be obtained. It is supposed that different mechanisms of ionization are realized at various laser intensities. Keywords: FAIMS, nitro compounds, laser, ionization, mobility. E-mail: anton_tu@list.ru