Vinylidene radical cation: a sizable barrier to unimolecular rearrangement to the acetylene radical cation

Hamilton, Tracy P.; Schaefer, Henry F.

doi:10.1021/j100359a010

Cited by 17 publications

(5 citation statements)

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“…[25][26][27] Recent charge inversion mass spectra of C 2 H 2 ϩ , produced by electron ionization from H 2 C-CCl 2 provide, indeed, compelling evidence for the existence of a long-lived vinylidene cation. 28 According to Baker 25 and Jursic, 27 the electronic ground state of vinylidene has 2 A 1 symmetry while Hamilton and Schaefer 26 place 2 B 1 below 2 A 1 .…”

Section: Quantum-chemical Calculationsmentioning

confidence: 99%

Kinetic-energy release in Coulomb explosion of metastable C3H52+

Głuch¹,

Fedor²,

Matt-Leubner³

et al. 2003

The Journal of Chemical Physics

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C 3 H 5 2+ , formed by electron impact ionization of propane, undergoes metastable decay into C2H2++CH3+. We have monitored this reaction in a magnetic mass spectrometer of reversed geometry that is equipped with two electric sectors (BEE geometry). Three different techniques were applied to identify the fragment ions and determine the kinetic-energy release (KER) of spontaneous Coulomb explosion of C3H52+ in the second and third field free regions of the mass spectrometer. The KER distribution is very narrow, with a width of about 3% [root-mean square standard deviation]. An average KER of 4.58±0.15 eV is derived from the distribution. High level ab initio quantum-chemical calculations of the structure and energetics of C3H52+ are reported. The activation barrier of the reverse reaction, CH3++C2H2+ (vinylidene), is computed. The value closely agrees with the experimental average KER, thus indicating that essentially all energy available in the reaction is partitioned into kinetic energy.

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Section: Quantum-chemical Calculationsmentioning

confidence: 99%

Kinetic-energy release in Coulomb explosion of metastable C3H52+

Głuch¹,

Fedor²,

Matt-Leubner³

et al. 2003

The Journal of Chemical Physics

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“…[1][2][3][4][5][6][7] Several models have been studied in the literature which are based either on an effective vibrational Hamiltonian or on a semiempirical or ab initio potential energy surface for the ground electronic state. [8][9][10][11][12][13][14] High-resolution spectroscopy has provided highprecision effective vibrational Hamiltonians of 12 C 2 H 2 and of some of its isotopomers like 12 C 2 HD. [3][4][5][6][7]15 In this context, Jonas et al 3 performed a detailed study of the bending dynamics of 12 C 2 H 2 showing the role of a Darling-Dennison resonance between the bends, beside the previously identified vibrational l-doubling resonance.…”

Section: Introductionmentioning

confidence: 99%

Vibrational time recurrences in a model of acetylene C212H2

Pals

Gaspard

1999

The Journal of Chemical Physics

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The time-dependent intramolecular vibrational dynamics of acetylene is investigated with the vibrogram method for the effective Hamiltonian obtained by Abbouti Temsamani and Herman [J. Chem. Phys. 102, 6371 (1995)]. The quantum recurrences evidenced by the vibrogram are shown to be in correspondence with emerging periodic orbits, especially, of the bending type. In this model, we find different kinds of bifurcations and, in particular, a birth of bending local modes as well as further bifurcations causing the destabilization of bending periodic orbits. This destabilization leads to a faster damping of the corresponding recurrences and to an increase in the intramolecular vibrational relaxation. A comparison with monodeuterated acetylene is also carried out.

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“…The isomerization between vinylidene and acetylene has been the subject of numerous experimental28, 32, 110, 180, 218, 219 and theoretical investigations 220–227 . Ab initio calculations showed a barrier of about 0.50 eV for the isomerization of vinylidene radical cation (X 2 B 1 ) to the acetylene radical cation (X 2 Π u ) 223–225. However, Jursic and coworkers reported high‐level ab initio calculations that show a very low activation barrier for the isomerization between the radical cations of vinylidene and acetylene 226…”

Section: Charge Inversion Mass Spectrometry Using Alkali Metal Targetsmentioning

confidence: 99%

“…Excited states of vinylidene cations were estimated by ab initio calculations,223–225 2 A 1 and 4 A 2 excited states are approximately 0.2 and 1.2 eV above ground state, respectively 224, 225. The less energetic Koopman's transition, in which the electronic structure except the transition electron is not rearranged, yields the 2 A 1 state of vinylidene cation, for which the barrier to isomerization to form the acetylene cation is only 0.2 eV.…”

Section: Charge Inversion Mass Spectrometry Using Alkali Metal Targetsmentioning

confidence: 99%

Charge inversion mass spectrometry: dissociation of resonantly neutralized molecules

Hayakawa

2004

J. Mass Spectrom.

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Charge inversion mass spectrometry is an MS/MS method in which the electric charge of the precursor ions is opposite to that of the secondary product ions. Charge inversion mass spectrometry is classified into four types depending on the electric charge and time scale of collisions. Charge inversion mass spectrometry using collisions with gaseous targets in the keV energy collision range has provided insights into the structures and reactions of ions and neutral molecules. The characteristics of charge inversion experiments are presented in terms of the reaction endothermicities and the cross sections and their dependence on the target species. In the case of rare-gas or simple molecular targets, double-electron transfer in one collision is effective to form positive ions from negative ions, while, in the case of alkali metal targets, successive single-electron transfers in two collisions is effective to form negative ions from positive ions. On the basis of the observed target-density dependence of the product ion intensity and thermochemical considerations for internal energy distribution using thermometer molecules, the charge inversion processes using alkali metal targets have been confirmed to occur by electron transfers in successive collisions and the dissociation processes are found to occur in energy-selected neutral species formed from near-resonant neutralization with alkali metal targets. While collisionally activated dissociation (CAD) is due to dissociation of activated ions with broad internal energy distributions, the charge inversion process using alkali metal targets is due to dissociation of energy-selected neutral species with narrow internal energy distributions. The charge inversion/alkali metal spectra provide clear differentiation of the isomeric cations of C(2)H(2), C(3)H(4) and dichlorobenzenes. The CAD spectra of these isomeric cations are similar.

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Vinylidene radical cation: a sizable barrier to unimolecular rearrangement to the acetylene radical cation

Cited by 17 publications

References 0 publications

Kinetic-energy release in Coulomb explosion of metastable C3H52+

Kinetic-energy release in Coulomb explosion of metastable C3H52+

Vibrational time recurrences in a model of acetylene C212H2

Charge inversion mass spectrometry: dissociation of resonantly neutralized molecules

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