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Gas‐phase ion‐molecule bimolecular and clustering reactions in dilute solutions of acetonitrile in xenon, krypton, argon, neon and helium
Author(s) -
Lilies Andreas J.
Publication year - 1989
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.1210240309
Subject(s) - chemistry , molar ionization energies of the elements , ionization , electron ionization , chemical ionization , ion , neon , krypton , xenon , mass spectrum , atomic physics , mass spectrometry , ion source , argon , analytical chemistry (journal) , physics , organic chemistry , chromatography
Gas‐phase bimolecular and clustering reactions of acetonitrile in Xe, Kr, Ar, Ne and He were studied at high chemical ionization pressures in the new coaxial ion source at Auburn. With electron energies near the ionization threshold, the mass spectra are exceedingly simple and are comprised of [CH 4 CH] + and clusters of [CH 4 CN] + with various ligands such as H 2 O and CH 3 CN. At higher electron energies many other peaks appear. The intensities of the new peaks depend upon the ionization potential of the charge transfer gas, the ionizing electron energy and the ion source conditions, and are due to reactions of fragment ions. Residence time distributions at electron energies above the ionization threshold (∼ 30 eV) demonstrate that two molecular structures are present in the ion beam at m / z 42, one presumably is protonated acetonitrile ([CH 3 CNH] + ) while the evidence indicates that the second species does not contain acidic hydrogens. With ionizing electron energies near threshold (∼ 10. 5 eV) only one structure is observed. Studies with electron energies near the ionization threshold under high‐pressure chemical ionization conditions result in greatly simplified mass spectra and are possible only because of the coaxial geometry of the ion source.