Photoionization and Fragmentation of Polyatomic Molecules

Chupka, W. A.

doi:10.1007/978-94-010-2153-1_27

Cited by 5 publications

(2 citation statements)

References 53 publications

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“…Thus, one can safely neglect the radiative decay of NO 2 + ã 3 B 2 . By measuring the relative intensities of metastable NO 2 + signals in the photoionization efficiency curves of NO 2 , Chupka estimated the dissociation lifetimes of NO 2 + ã 3 B 2 (0, n 2 ,0) as follows: τ ≥ 150 μs for n 2 = 0, τ = 55 μs for n 2 = 1, τ = 15 μs for n 2 = 2, τ ≤ 5 μs for n 2 = 3. Chupka's lifetime values are 1 order of magnitude shorter than ours but almost parallel ours.…”

Section: Discussionmentioning

confidence: 99%

Dissociation of State-Selected NO₂⁺ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

et al. 1997

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Fragmentation patterns and dissociation rates of state-selected NO 2 + ions were measured by the threshold photoelectron-photoion coincidence (TPEPICO) method in the region of 40-100 nm. Parent NO 2 + ions were detected when they were prepared in the excited states located above the first dissociation limit (D 0 0 ) 2.79 eV), correlating to NO + (X 1 Σ + ) + O( 3 P). Specially, the dissociation rate (k dis ) of NO 2 + ions in the lowest excited a ˜3B 2 state increases with increasing the quantum number of the bending vibration (n 2 ): (7.4 ( 4.9) × 10 2 , (1.32 ( 0.56) × 10 3 , (1.51 ( 0.40) × 10 4 , and (2.38 ( 0.51) × 10 4 s -1 for n 2 ) 0, 1, 2, and 3, respectively. The branching ratios of two dissociation pathways, NO + + O and O + + NO, were found to depend on the electronic state of the parent ion. The unimolecular dissociation channels are discussed in terms of dissociation potential surfaces open for individual electronic states and radiative relaxation to lower electronic states.

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Section: Discussionmentioning

confidence: 99%

Dissociation of State-Selected NO₂⁺ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

et al. 1997

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“…Through the rate constant k ( E ), this time selection is equivalent to the selection of a relatively narrow range of internal energies. Accordingly, the internal-energy distribution of the parent ions is given by the product of a transmission function, T ( E ), that depends on the rate constant k ( E ), ,,− and of the branching ratio R ( E ) corresponding to the selected dissociation channel (here, C 4 H 4 + + C 2 H 2 ), that is, the ratio between the ion current for the fragment of interest and the total ion current at internal energy E T ( E ) = A [ exp ( − k ( E ) τ 1 ) − exp ( − k ( E ) τ 2 ) ] R ( E ) where A is a normalization constant.…”

Section: Methodsmentioning

confidence: 99%

The Role of Long-Range Forces in the Determination of Translational Kinetic Energy Release. Loss of C₄H₄⁺ from the Benzene and Pyridine Cations

et al. 2008

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Kinetic energy release distributions (KERDs) for the benzene ion fragmenting into C 4H 4 (+) and C 2H 2 have been recorded by double-focusing mass spectrometry in the metastable energy window and by a retarding field experiment up to an energy of 5 eV above the fragmentation threshold. They are compared with those resulting from the HCN loss reaction from the pyridine ion. Both reactions display a similar variation of the kinetic energy release as a function of the internal energy: the average release is smaller than statistically expected, with a further restriction of the phase-space sampling for the C 5H 5N (+) dissociation. Ab initio calculations of the potential-energy profile have been carried out. They reveal a complicated reaction mechanism, the last step of which consists in the dissociation of a weakly bound ion-quadrupole or ion-dipole complex. The KERDs have been analyzed by the maximum entropy method. The fraction of phase space effectively sampled by the pair of fragments has been determined and is similar for both dissociations. Both reactions are constrained by the square root of the released translational energy, epsilon (1/2). This indicates that in the latter stage of the dissociation process, the reaction coordinate is adiabatically decoupled from the bath of the bound degrees of freedom. For the C 6H 6 (+) fragmentation, the analysis of the experimental results strongly suggests that, just as for a spherically symmetric interaction potential, the translational motion is confined to a plane. For the dissociation of the pyridine ion, the main dynamical constraint is also a restriction to a two-dimensional subspace. This dimensionality reduction of the translational phase space is due to the fact that the Hamiltonian of both weakly bound complexes contains a cyclic coordinate.

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Interactions of Slow Electrons with Benzene and Benzene Derivatives

Christophorou

Grant

McCorkle

1977

Advances in Chemical Physics

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Photoionization and Fragmentation of Polyatomic Molecules

Cited by 5 publications

References 53 publications

Dissociation of State-Selected NO₂⁺ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

Dissociation of State-Selected NO₂⁺ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

The Role of Long-Range Forces in the Determination of Translational Kinetic Energy Release. Loss of C₄H₄⁺ from the Benzene and Pyridine Cations

Interactions of Slow Electrons with Benzene and Benzene Derivatives

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Photoionization and Fragmentation of Polyatomic Molecules

Cited by 5 publications

References 53 publications

Dissociation of State-Selected NO2+ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

Dissociation of State-Selected NO2+ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

The Role of Long-Range Forces in the Determination of Translational Kinetic Energy Release. Loss of C4H4+ from the Benzene and Pyridine Cations

Interactions of Slow Electrons with Benzene and Benzene Derivatives

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Dissociation of State-Selected NO₂⁺ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

Dissociation of State-Selected NO₂⁺ Ions Studied by Threshold Photoelectron−Photoion Coincidence Techniques

The Role of Long-Range Forces in the Determination of Translational Kinetic Energy Release. Loss of C₄H₄⁺ from the Benzene and Pyridine Cations