Chapter 2 Mass Spectrometry

Derrick, Peter J.; Donchi, Kevin F.

doi:10.1016/s0069-8040(08)70204-8

Cited by 13 publications

(6 citation statements)

References 809 publications

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13] The information is presented as a function, denoted P( |E), giving the probability of generating fragments with a relative translational energy equal to , if E denotes the internal energy measured in excess of the dissociation threshold.…”

Section: Introductionmentioning

confidence: 99%

Unimolecular Reaction Dynamics from Kinetic Energy Release Distributions. 8. Protonated Fluorobenzene and Structure of the Phenyl Ion

Lorquet

2001

J. Phys. Chem. A

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A previous interpretation of the kinetic energy release distribution (KERD) observed in the fragmentation of protonated fluorobenzene is confirmed by a maximum entropy analysis. The KERD is bimodal, with an intense and broad component due to the production of the cyclic phenyl ion. Ab initio calculations indicate the existence of several open-chain isomers, with an energy about 1.0-1.2 eV higher than that of the phenyl ring. A weaker component of the KERD corresponds to the formation of one or several of these acyclic structures. Its abundance represents about 6% of the main component (but drops down to 3% for the perdeuterated isomer). More translational energy than the statistical estimate is released during the dissociation process because of the presence of a barrier along the reaction path leading to the generation of the cyclic phenyl ion. About one-half of the energy of the barrier is released as translation, thereby indicating the operation of strong exit-channel interactions between separating fragments.

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Section: Introductionmentioning

confidence: 99%

Unimolecular Reaction Dynamics from Kinetic Energy Release Distributions. 8. Protonated Fluorobenzene and Structure of the Phenyl Ion

Lorquet

2001

J. Phys. Chem. A

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“…Energy-resolved data, not restricted to molecular cations, also can be obtained from mass-resolved studies of the single-photon photodissociation of gaseous ions by varying the wavelength of the incident photons (9,10). More qualitative data on the energy dependence of ionic fragmentation reactions can be obtained from energyresolved (ERMS) collisional experiments (1 1 -13), from angleresolved (ARMS) collisional experiments (13,14), and from field ionization kinetics (FIK) measurements (15,16), the latter also being limited to odd-electron molecular cations. With this extensive annoury of techniques, the study of the energy dependence of the fragmentation of organic cations is a wellestablished field.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation of alkoxide ions following collisional activation. An energy-resolved study

Mercer¹,

Harrison²

1988

Can. J. Chem.

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. Can. J. Chem. 66, 2947Chem. 66, (1988.The collisionally activated dissociation reactions of the C2 to C5 alkoxide ions have been studied for collisons occurring at 8 keV kinetic energy and also over the range 5 to 100 eV kinetic energy. The alkoxide ions fragment by 1,2-elimination of H2 andlor an alkane. Thus, primary alkoxide ions fragment by elimination of H, only, secondary alkoxide ions show elimination of Hz and alkane molecules, while tertiary alkoxide ions show elimination of alkanes only. In alkane elimination, loss of CH4 is much more facilie than loss of larger alkanes. For secondary alkoxide ions, where more than one elimination reaction occurs, the energy dependence of fragmentation has been explored over the collision energy range 5 to 100 eV. The results are interpreted in terms of a step-wise mechanism involving formation of an anion-carbonyl compound ion-dipole complex, followed by proton abstraction by the H-or alkyl anion leading to the final products. The relative importance of the reaction channels is determined by the relative stabilities of these ion-dipole complexes. ROGER S. MERCER et ALEX G. HARRISON. Can. J. Chem. 66,2947 (1988.On a CtudiCe les reactions de dissociation des ions alcoolates C2 a CS activkes par des collisions se produisant i une Cnergie cinktique de 8 keV ainsi qu'i des energies cinetiques allant de 5 a 100 eV. Les ions alcoolates se fragmentent par une elimination-l,2 de Hz eVou d'alcane. Ainsi, les ions alcoolates primaires se fragmentent uniquement par une elimination de Hz; par ailleurs, les ions alcoolates secondaires presentent de l'elimination de H2 ainsi que celle de molecules d'alcanes alors que les ions alcoolates tertiaires ne presentent que de l'elimination d'alcanes. Lors de l'elimination d'alcanes, la perte de CH4 est beaucoup plus facile que celle des alcanes plus volumineux. Dans le cas des alcoolates secondaires oh il se produit plus d'une elimination, on a CvaluC la relation qui existe entre I'energie de collision (de 5 100 eV) et le type de fragmentation. On interprete les resultats en fonction d'un mecanisme par Ctape impliquant la formation d'un complexe ion-dip6le d'un compose anioncarbonyle, suivie par l'enlevernent d'un proton par un H-ou par un anion alkyle, conduisant aux produits. On a determine l'importance relative des diverses voies rtactionnelles en se basant sur les stabilites relatives de ces complexes ion-dip6les.[Traduit par la revue] Introduction Studies of the fragmentation of gaseous ions have long been invaluable sources of information concerning the structures and chemistry of such species (1, 2). This information is even more useful if the internal energy of the fragmenting ions is known and can be varied in a controlled fashion; such energy-resolved studies permit the establishment of break-down graphs expressing the variation of fragment ion yields with internal energy. Energy-resolved data for odd-electron molecular cations can be obtained with high precision by photoelectron/photoion coincidence (PEPICO) experiments (3-5)...

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“…In the case of the t-butylamine molecular ion, making the simple assumption that the methyl group departs in the plane of symmetry, treatment of the energy partitioning in terms of the direction of the transition state reaction co-ordinate (dynamical theory) predicts the release of a significant fraction of a reverse critical energy as translational energy,gJ6 whereas reactions in which the neutral released contains more than 4 or 5 atoms normally do not release translational energy to any great extent during dissociation . 9 The reverse critical energies (perhaps 2500 cm-1) proposed for the amine reactions, corresponding to very few quanta of vibrational energy, would require very little reorganization within the incipient products (curvature of the reaction co-ordinate) to be dissipated.…”

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confidence: 99%