Thermal desorption metastable atom bombardment ionization aerosol mass spectrometer

摘要: Abstract A metastable atom bombardment (MAB) ionization source has been coupled to an existing thermal desorption aerosol mass spectrometer. The design allows real-time alternation between MAB and electron (EI). jet of species produced in a DC discharge is directed at the volume spectrometer, where Penning thought be dominant mechanism. Performance characterized experiments with oleic acid particles. By changing gases N 2 , Kr, Ar, excited state energy can adjusted range 8.5–11.7 eV. For vaporization 180 °C, all yield significantly less fragmentation than EI, which could improve results factor analysis. Fragmentation increases temperature, but generated fragments have higher average those by EI. Analyte signal levels are 0.1% 0.006% equivalent analysis EI when using Ar * Kr respectively. These sensitivities not practical for ambient studies, sufficient measurements, as demonstrated direct measurements biomass burning emissions. measured flux 3.6 × 10 13  sr −1  s ∼30 times lower best literature values similar beam sources, suggesting that sensitivity increased improvements.