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Observation of isolated electronic states in the collision‐induced dissociation of nitromethane ions
Author(s) -
Qian Kuangnan,
Shukla Anil,
Futrell Jean
Publication year - 1990
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.1290040611
Subject(s) - chemistry , nitromethane , dissociation (chemistry) , ion , excited state , atomic physics , collision induced dissociation , intramolecular force , tandem mass spectrometry , ground state , polyatomic ion , mass spectrometry , stereochemistry , physics , organic chemistry , chromatography
Collision‐induced dissociation of nitromethane molecular ions to NO + and NO 2 +has been studied at 19 eV center‐of‐mass collision energy using a crossed‐beam tandem mass spectrometer. Center‐of‐mass velocity contour maps for the two dissociation processes are distinctly different; NO 2 +has its intensity maximum at 7 degrees with energy transfer endothermicities of 1.8 eV while NO + has intensity maxima at zero and 8 degrees with energy transfer endothermicities of 0.3 and 5.5 eV, respectively. The observation of two distinct peaks in the NO + contour map clearly demonstrates that nitromethane ions excited to 5.5 eV internal energy do not dissociate from the ground state potential surface. Dissociation is faster than intramolecular relaxation, in contradiction to the fundamental postulate of statistical theories (RRKM, QET) for unimolecular dissociation.