A millisecond pulsed glow discharge is used as a versatile ion source for time-gated generation of elemental, structural, and molecular ions. The utility of this ion source for comprehensive chemical analysis of a series of aromatic and halogenated hydrocarbons is illustrated in this manuscript. To highlight the analytical utility of this transient ion source, it was connected to a gas chromatograph for the mass spectrometric determination of mixtures containing benzene, toluene, o-xylene, cymene, tert-butylbenzene, carbon tetrachloride, chloroform, chlorobenzene, tetrachlorethane, and dichlorobenzene. Explicit chemical analysis was accomplished by introducing the GC eluent into a pulsed glow discharge operating at a rate of 100 Hz with a 50% duty cycle. Using three independent digitizers for time-gated acquisition in three separate time regimes, nearly concurrent collection of elemental, structural, and molecular information was accomplished. In general, elemental information was obtained during the first 0.015 ms after the plasma onset; structural information, as ascertained from molecular fragmentation, was obtained during the plateau time regime when the plasma pulse is at a steady state, whereas molecular M(+) and MH(+) ions were obtained during the afterpeak time regime, that is, after the cessation of the plasma power pulse.

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Lead liquid metal ion sources (LMISs) were operated using a special specimen holder in situ in a 1 MeV TEM. The dynamics of the tip shape have been observed as a function of the ion emission current. At currents there was a jet-like protrusion on the vertex of the Taylor cone. Linear dependences were found for the decrease of the cone half-angle and the increase of the jet length l as functions of increase in ion emission current. Microdroplet emission was observed at the shank of the Taylor cone over time intervals of 0.1 s and more. The diameter of these microdroplets varied between 40 and 340 nm. This work has improved our understanding of the ion and microdroplet emission processes from the Pb LMIS.