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High‐pressure photoionization mass spectrometry. Effect of internal energy and density on the ion–molecule reactions occurring in methyl, dimethyl, and trimethylamine
Author(s) -
Hellner L.,
Sieck L. W.
Publication year - 1973
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550050202
Subject(s) - chemistry , dimethylamine , photoionization , methylamine , molecule , mass spectrometry , solvation , ion , analytical chemistry (journal) , photochemistry , ionization , organic chemistry , chromatography
The ion–molecule reactions of CH 3 NH 2 + , (CH 3 ) 2 NH + , and (CH 3 ) 3 N + with the respective amines have been investigated at thermal kinetic energies in a high‐pressure photoionization mass spectrometer at several wavelengths (energies) in the vacuum ultraviolet. The absolute rate coefficient for proton transfer from (CH 3 ) 3 N + to (CH 3 ) 3 N decreases from 8.2 × 10 −10 cm 3 /molecule · sec at 147.0 nm (8.4 eV) to 4.9 × 10 −10 cm 3 /molecule. sec at 106.7‐104.8 nm (11.7 eV). In dimethylamine, the rate coefficient decreases from 11.6 × 10 −10 cm 3 /molecular. sec at 8 4 eV to 10.2 × 10 −10 cm 3 /molecule osec at 11.7 eV, while no significant effect of energy was detected in methylamine. The reactions of several fragment ions are also reported. Experiments were also carried out at pressures up to 0.5 torr in order to investigate the further solvation of CH 3 NH 2 + , (CH 3 ) 2 NH 2 + , and (CH 3 ) 3 NH + . It was found that the maximum proton solvation numbers in methyl‐, dimethyl‐, and trimethyl‐amine are 4, 3, and 2, respectively, under these conditions.