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The extent of internal excitation of the protonated molecules of some liquid martices bombarded by keV Cs + ion beams
Author(s) -
Hamdan M.
Publication year - 1992
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290060315
Subject(s) - chemistry , protonation , ion , dissociation (chemistry) , ionization , molecule , chemical ionization , mass spectrometry , mass spectrum , electron ionization , excitation , collision induced dissociation , analytical chemistry (journal) , ion source , reagent , spectral line , atomic physics , tandem mass spectrometry , organic chemistry , chromatography , physics , astronomy , electrical engineering , engineering
In an attempt to probe the extent of internal excitation of protonated ions formed by positive fast‐ion bombardment, the protonated molecules of four commonly used liquid matrices are formed by means of the above technique and their respective mass‐selected collision‐induced dissociation (CID) spectra are investigated within the collision energy range, 5‐200 eV (in the laboratory frame of references). These measurements are also repeated for the same four precursor ions formed by means of positive‐ion chemical ionization in two different reagent gases, NH 3 and CH 4 . The observed dissociation channels and the relative peak heights associated with them imply that the internal excitation of protonated molecules formed by fast‐ion bombardment is much higher than that associated with the protonated ions formed in positive‐ion ammonia CI(NH 3 ‐CI + ). On the other hand, close resemblance between the CID spectra of ions formed by the first technique, by CH 4 ‐CI + and by electron ionization is clearly evident.