Collisional ionization mass spectra of a fast beam of neutral molecules with ionization potentials in the range 4-5 eV have been obtained with a series of target gases, NO2, O2, N2 and He. Neutral beams were generated in a near resonant electron transfer process X+ +K(g) → X* + K+ where X+ is He2+, H3+, ND4+ or N2D7+. The efficiency of collisional ionization of metastable He2* and the ground state radicals ND4 and N2D7 on target gas decreases in the order NO2 > O2 > N2 > He. Of the four neutral species studied, only in the case of H3* is a change in rotational state of the projectile required for ionization. This restriction may explain the lack of an apparent target gas dependence on the efficiency of ionizing H3*. The technique is extended to a study of the CD5 radical where no evidence for metastability is observed. An upper limit of 10-8 s is set on the lifetime of this species.
|Number of pages||12|
|Journal||International Journal of Mass Spectrometry and Ion Processes|
|State||Published - Mar 15 1985|