Development of Sniffing Atmospheric Pressure Penning Ionization

抄録

The atmospheric pressure Penning ionization was applied to the analysis of atmospheric-pressure ambient gaseous samples. The metastable rare gas atoms (Rg*) were produced by a negative-mode corona discharge of reagent rare gas (Rg). The rare gas containing Rg* in the discharge cell flowed out into the ion source cell through a nozzle with an inner diameter of 1 mm as a jet stream. The jet stream acts as a gas-jet pump and the pressure of the ion source cell becomes somewhat lower than the atmospheric pressure. The sample gas at ambient atmospheric pressure was sucked into the reduced-pressure ion source cell through the stainless steel tube (10 cm in length, 1 mm in diameter). The sample gases introduced in the ion source cell are ionized by Penning ionization. This technique was found to be applicable to various gaseous samples such as aromatic compounds, oxygen- and nitrogen-containing compounds, etc. However, no ion signal could be detected for aliphatic hydrocarbons. This may be due to the much smaller ionization cross sections for these compounds than N₂ and O₂ molecules which are introduced into the ion source together with sample gases.