Results are presented which characterize the vacuum ultraviolet H2 laser as a selective ion source for analytical mass spectrometry of easily ionized compounds. The types of compounds ionized below the photon energy of 7.8 eV include many pharmaceuticals and drugs of abuse, such as cocaine, heroin, phencyclidine, methamphetamine, and LSD. Hydrogen laser photoionization has produced parent ions only, for all compounds studied thus far. The selectivity of the threshold photoionization process is very high, as compounds within as little as 0.2 eV above the threshold are completely rejected. Photoactive species can be injected as solutions in appropriate organic solvents, without interference from the solvent. At low levels, ion signals are observed, which are due to acceleration of stray electrons in the ion source. The electrons result from interaction of scattered laser radiation with metal surfaces.
|Original language||English (US)|
|Number of pages||10|
|Journal||International Journal of Mass Spectrometry and Ion Processes|
|Publication status||Published - Nov 25 1985|
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