Fragramention of energy-selected nitromethane ions

Niwa, Yoshio; Tajima, Susumu; Tsuchiya, Toshikazu

doi:10.1016/0020-7381(81)80093-9

Cited by 27 publications

(20 citation statements)

References 11 publications

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“…However, we measured it to be only 0.054 ± 0.005 eV, in good agreement with the literature. 8 The large excess energy but small release suggests that nitromethane ion isomerizes with a subsequent simple bond cleavage to the NO+ ion. An isomerization to the intermediate methylnitrite structure is the most reasonable one consistent with these requirements.…”

Section: Resultsmentioning

confidence: 99%

“…6 ,7 Studies using these methods have focused primarily on the excited states of the neutral molecule and on the formation of free radicals; however, relatively few investigations of the formation and unimolecular decomposition of nitromethane ions have been reported. [6][7][8][9][10][11][12] The absorption and emission spectra of the nitro methane molecule can now be interpreted quite well, 1 but the fragmentation behavior of the nitromethane ion is still not fully understood.…”

Section: Introductionmentioning

confidence: 99%

“…8 The decrease in the relative abundance of the NO' breakdown curve with respect to increasing internal energy, and the subsequent increase in relative abundance of this breakdown curve in the region of the fifth ionization band in the photoelectron spectrum (PES), was interpreted as evidence for the formation of NO' from • .l.n .. isolated" electronic state of the nitromethane mo-1ecular ion. Similarly, the breakdown curves and the kinetic energy release (KER) indicated that the fragmentation to CHi +N0 2 proceeded via an isolated electronic state of the molecular ion and could not be interpreted on the basis of the quasiequilibrium theory (QET) of mass spectra.…”

Section: Introductionmentioning

confidence: 99%

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Competition between isomerization and fragmentation of gaseous ions. II. Nitromethane and methylnitrite ions

Gilman

Hsieh

Meisels

1983

The Journal of Chemical Physics

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Nonadiabatic unimolecular reactions. III. Dissociation mechanisms of methylnitrite and deuterated methylnitrite ions J. Chem. Phys. 88, 5606 (1988); 10.1063/1.454571The unimolecular decomposition rates of energy selected methylnitrite and deuterated methylnitrite ions Major fragmentation pathways of the nitromethane and methylnitrite ions have been examined. Ionization and fragmentation onsets for these processes have been determined and breakdown graphs have been constructed for both compounds using a threshold photoelectron-photoion coincident (TPEPICO) mass spectrometer. At onset, fragmentation of the nitromethane ion to NO+ is preceded by isomerization to the energetically favored methylnitrite ion; the barrier to isomerization is 0.64 eV. Symmetry considerations indicate that the nitromethane ion in its 2A2 (1T) state correlates with the 2A "(1T) state of the methylnitrite ion through which dissociation to the NO+ fragment occurs.1174

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Competition between isomerization and fragmentation of gaseous ions. II. Nitromethane and methylnitrite ions

Gilman

Hsieh

Meisels

1983

The Journal of Chemical Physics

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“…Molecular beam studies of the CAD of the nitromethane cation [41] (which also has electronically isolated states [40]) have indicated that its low energy CAD also involves electronic transitions (rather than vibrational excitation) [41]. Other examples of non-QET behavior have been reported previously [42][43][44].…”

Section: Energy Transfer Efficiency4mentioning

confidence: 99%

Kinetics and mechanism of the collision-activated dissociation of the acetone cation

Martinez

Ganguli

1992

J. Am. Soc. Mass Spectrom.

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For center-of-mass collision energies Ecm = 1-60 eV, the major fragment ions for the collision-activated dissociation (CAD) of the acetone cation are the acetyl cation (m / z 43; absolute branching ratios of 0.96-0.60) and the methyl cation (m/ z 15; absolute branching ratios of 0.02-0.26); the absolute total cross-sections were 24-35) Å(2). The breakdown curves (viz, plots of the absolute branching ratios versus Ecm) show complex, complementary energy dependences for production of MeCO(+) and Me(+), indicating apparent closure of the Me(+) channel for Ecm > 30 eV. Our observations are consistent with a competition between three fast, primary (direct) reactions, each of which opens sequentially at its respective threshold energy (viz, reactions 8, 10, and 8'). [Formula: see text] [Formula: see text] [Formula: see text] That is, the breakdown curves for MeCO(+) and Me(+) (and other CAD fragments) are consistent with the interpretation by other authors that the collisional activation of the acetone cation involves electronic transitions, so that CAD occurs primarily from isolated electronic states (i.e., non-quasi-equilibrium theory (QET) behavior). For acetone we found a correspondence between the photoelectron-photoion-coincidence and CAD breakdown curves. This may indicate that collisional activation in non-QET systems corresponds to scattering angles that emphasize optically allowed transitions accessed by photoionization.

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“…NO' ions are formed prevalently in the dissociative ionization of a variety of molecular species and nitromethane is of interest as the near-threshold breakdown behaviour has been studied by photoelectron-photoion coincidence spectroscopy (Niwa et al 1981). From this and other studies the m / z = 3 0 (NO+) species are known to be formed from parent ions with internal energies of either between about 0.6 to 1.9 eV or greater than 5.6 eV.…”

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Hydrogen Storage in Amorphous Phase of Hydrogenated Carbon Nitride

Ohkawara

Ohshio

Suzuki

et al. 2002

Jpn. J. Appl. Phys.

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Charge-inversion mass spectrosmpy has been used to study fast beams of 0 : . NO+, CF'+. CH+. NH' and CN+ cations formed from given precursor molecules under 1W eV electron impact. Beams of 0: and NO+ formed from the respective gases. and CF'+ farmed from CF,, were found to contain 0.48+0.05,0.45 * O M and 0.38*0.08 proportions of metastable ions. In contrast, NO+ ions formed from nitromethane, and CF+ ions from CHF,, were almost entirely in their ground states. Significant but indeterminable proportions of %-state ions were iound in beams of CH' ions formed from CFH, and CH, wide the beam of NH+ ions formed from NH, has been estimated to contain at least 25% of excited 'Z-ions. Beams of CNI ions formed from CN,H,, HCN and nitromethane gave spectra that suggest the presence of a large proportion of electronically excited cations, possibly in vibrationally hot levels of the ' n state. All spectra are discussed in the light of these statc distributions and with regard to the ersicitics and Franck-Condan factors for the single electron capture reactions involved.

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Fragramention of energy-selected nitromethane ions

Cited by 27 publications

References 11 publications

Competition between isomerization and fragmentation of gaseous ions. II. Nitromethane and methylnitrite ions

Competition between isomerization and fragmentation of gaseous ions. II. Nitromethane and methylnitrite ions

Kinetics and mechanism of the collision-activated dissociation of the acetone cation

Hydrogen Storage in Amorphous Phase of Hydrogenated Carbon Nitride

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