title: The effects of added hydrogen on a helium atmospheric-pressure plasma jet ambient desorption/ionization source.
abstract: We present mass spectrometric data demonstrating the effect that hydrogen has on a helium-based dielectric-barrier discharge (DBD) atmospheric-pressure plasma jet used as an ambient desorption/ionization (ADI) source. The addition of 0.9 % hydrogen to the helium support gas in a 35-W plasma jet increased signals for a range of test analytes, with enhancement factors of up to 68, without proportional increases in background levels. The changes in signal levels result from a combination of changes in the desorption kinetics from the surface and increased ion production in the gas phase. The enhancement in ADI-MS performance despite the quenching of key plasma species reported in earlier studies suggests that ionization with a H2/He plasma jet is the result of an alternate mechanism involving the direct generation of ionized hydrogen.
authors: Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
authors: Jonathan P
authors: JP
authors: Wright
authors: Matthew S
authors: MS
authors: Heywood
authors: Glen K
authors: GK
authors: Thurston
authors: Paul B
authors: PB
authors: Farnsworth
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