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Photodissociation of alkane ions in the source of a mass spectrometer: A potential analytical technique
Author(s) -
Kim M. S.,
Morgan T. G.,
Kingston E. E.,
Harris F. M.
Publication year - 1983
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210181217
Subject(s) - ion , photodissociation , mass spectrum , mass spectrometry , ionization , electron ionization , spectral line , chemistry , alkane , analytical chemistry (journal) , atomic physics , hydrocarbon , physics , photochemistry , organic chemistry , chromatography , astronomy
Alkane ions generated by 70 eV electron ionization are irradiated in the source of a reversed geometry, double focusing mass spectrometer by 2.41 eV (514.5 nm) photons from an argon ion laser. The ions in the chamber are extracted, accelerated to 6 keV and spectra obtained by scanning the field of the magnet. The laser light is mechanically chopped and changes in the peak heights of the mass spectra resulting from photodissociation of ions in the ion chamber are recorded using a phase‐sensitive detector to give what are referred to as photoinduced spectra. The peaks for the molecular ions of alkanes are large relative to other peaks in the photoinduced spectra, a situation which contrasts with that for the mass spectra. The relative photodissociation cross‐sections of several alkanes, C 6 C 10 , C 12 and C 16 , have been measured and those of linear and branched [C 10 H 22 ] + ˙ ions are compared. Some of the characteristic features of the photoinduced spectra make the identification of the sample simpler than from mass spectra. The method is applied to the analysis of some alkane mixtures and its potential in analytical work discussed.