Gas chromatography resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (GC/REMPI-TOFMS) using a nanosecond laser has been applied to analyze the 16 polycyclic aromatic hydrocarbons (PAHs). The excited-state lifetime, absorption characters, energy of electronic states of the 16 PAHs were investigated to optimize the ionization yield. The results suggested that REMPI is superior to elctron impact ionization method for soft ionization, and suppresses the background signal caused by the aliphatic hydrocarbons. Thus, GC/REMPI-TOFMS is a more reliable method for the determination of PAHs present in the environment.
Multiphoton ionization (MPI) mechanism in the solid state being still controversial we
coupled a tunable laser to the LAMMA 500 microprobe to reinvestigate, using different
UV irradiations, the ionization of some organic and organometallic solid compounds.
Two polycyclic aromatic hydrocarbons (PAH) anthracene and pyrene and metallic
derivatives of copper and cadmium were tested. Preliminary results are consistent with
thermal desorption of neutral molecules as the first step followed by photoionization
in the vapor phase.Thus the ionization mechanisms described for gases or vapors, and in particular some
REMPI or RIS processes appear to apply to our experimental conditions.
Trace Analysis of Polycyclic Aromatic Hydrocarbons Using Gas Chromatography–Mass Spectrometry Based on Nanosecond Multiphoton Ionization
