Structure and dynamics of molecules in high charge states

Mathur, D.

doi:10.1016/j.physrep.2003.10.016

Cited by 171 publications

(103 citation statements)

References 322 publications

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“…The final breakup of the hot, highly charged nanoplasma yields energetic electrons, x-rays, as well as ions with kinetic energies that can be as high as a few MeV, 2 up to five orders of magnitude larger than the energies obtained upon Coulomb explosion of monomeric species such as multiply charged molecules. 7 Mechanisms other than IB that might play a role in energy transfer from the optical field to the cluster are of noncollisional nature, including resonance absorption 8 and vacuum ͑or Brunel͒ heating. 9 We obviate the need to consider these processes in the present study by taking recourse to few-cycle laser pulses with peak intensities that lie below 10 15 W cm −2 .…”

Section: Communication: Ionization and Coulomb Explosion Of Xenon Clumentioning

confidence: 99%

Communication: Ionization and Coulomb explosion of xenon clusters by intense, few-cycle laser pulses

Mathur

Rajgara

2010

The Journal of Chemical Physics

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Intense, ultrashort pulses of 800 nm laser light (12 fs, ∼4 optical cycles) of peak intensity 5×10 14 W cm −2 have been used to irradiate gas-phase Xe n clusters (n=500-25,000) so as to induce multiple ionization and subsequent Coulomb explosion. Energy distributions of exploding ions are measured in the few-cycle domain that does not allow sufficient time for the cluster to undergo Coulombdriven expansion. This results in overall dynamics that appear to be significantly different to those in the many-cycle regime. One manifestation is that the maximum ion energies are measured to be much lower than those obtained when longer pulses of the same intensity are used. Ion yields are cluster-size independent but polarization dependent in that they are significantly larger when the polarization is perpendicular to the detection axis than along it. This unexpected behavior is qualitatively rationalized in terms of a spatially anisotropic shielding effect induced by the electronic charge cloud within the cluster.

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Section: Communication: Ionization and Coulomb Explosion Of Xenon Clumentioning

confidence: 99%

Communication: Ionization and Coulomb explosion of xenon clusters by intense, few-cycle laser pulses

Mathur

Rajgara

2010

The Journal of Chemical Physics

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“…-Dissociation: τ = 4 s (Mathur et al 1995;Mathur 2004). -Reaction with O: the reaction rate has never been measured, due to the very unstable and reactive character of the oxygen radical.…”

Section: Photochemistrymentioning

confidence: 99%

Modelling dications in the diurnal ionosphere of Venus

Gronoff¹,

Lilensten²,

Simon³

et al. 2007

A&A

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Context. Previous studies have shown that doubly-charged positive ions, including molecular ions, can have detectable densities in the ionospheres of Mars, Titan, and the Earth. Aims. In the present paper, we continue our approach by modelling the Venusian ionosphere. The neutral atmosphere of Venus has a similar composition to the ones encountered in the other terrestrial planets, with carbon dioxide (as on Mars), nitrogen (as on Earth and Titan), and atomic oxygen (as on Earth). Methods. We computed the doubly-charged positive ion production through photoionisation (primary production) and electron impact ionisation (secondary production). We computed the densities under the photochemical equilibrium assumption. Results. We predict a CO 2 ++ layer centred around 140 km altitude with a density reaching 30 dications per cm 3 in active solar conditions and a N 2 ++ layer centred around a 140−150 km altitude with density reaching 0.3 cm −3 . We find good agreement between the modelled O ++ densities and Pioneer Venus Orbiter measurements. Finally, we investigate the problem of possible detection of these ions by the European spacecraft Venus Express. Conclusions. Although molecular doubly-charged positive ion densities are low, these ions cannot be considered as negligible compared to other minor ion species. Their detection should be possible in the future through remote sensing or in-situ methods including ion mass spectrometry and UV spectroscopy.

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“…For multielectron molecules, enhanced ionization creates multiply charged molecular ions, which immediately undergo Coulomb explosions due to nuclear repulsion. 65 It is shown that field-induced intramolecular electronic dynamics also causes chemical reactions (fragmentations) 48,66 other than Coulomb explosions. Intramolecular electronic dynamics, which triggers both enhanced ionization and reaction dynamics, is therefore regarded as the key process to control the competition between the ionization and the reaction of molecules.…”

Section: Multiphoton Ionization and Tunnel Ionizationmentioning

confidence: 99%

Theoretical Investigations of the Electronic and Nuclear Dynamics of Molecules in Intense Laser Fields: Quantum Mechanical Wave Packet Approaches

Kono

Satô

Kanno

et al. 2006

Bulletin of the Chemical Society of Japan

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We have developed a method for describing the reaction dynamics of a polyatomic molecule in intense laser fields. First, the dynamical behavior of H 2 þ and H 2 in near-infrared, intense laser fields (I > 10 13 W cm À2 and ! > 700 nm) was examined; accurate evaluation of the electronic and nuclear wave packet was achieved by the dual transformation method that we developed. Using ''field-following'' time-dependent adiabatic states defined as eigenfunctions of the ''instantaneous'' electronic Hamiltonian, we have clarified the dynamics of bound electrons, ionization processes, Coulomb explosion processes, and molecular vibrations of H 2 þ and H 2 . The analyses indicate that the multielectron dynamics and nuclear dynamics of polyatomic molecules in intense fields can be described by using the potential surfaces of time-dependent adiabatic states and the nonadiabatic coupling elements between those states. To obtain time-dependent adiabatic states of a molecule, one can diagonalize the electronic Hamiltonian including the interaction with the instantaneous laser electric field by ab initio molecular orbital (MO) methods. The time-dependent adiabatic potentials obtained are used to evaluate the multichannel nuclear dynamics until the next ionization process. We have applied the time-dependent adiabatic state approach to reveal the characteristic features of the dynamics of structural deformations of CO 2 and its cations in a near-infrared intense laser field. The experimentally observed stretched and bent structure of CO 2 3þ just before Coulomb explosions originates from the structural deformation of CO 2 2þ . We also revealed the mechanism of the experimentally observed bond dissociation of C 2 H 5 OH; we found that the relative probability of C-O bond cleavage to that of C-C bond cleavage becomes smaller with decreases in the pulse length. This example clearly shows that field-induced nonadiabatic transitions play a decisive role in the reaction dynamics of molecules in an intense laser field.

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Structure and dynamics of molecules in high charge states

Cited by 171 publications

References 322 publications

Communication: Ionization and Coulomb explosion of xenon clusters by intense, few-cycle laser pulses

Communication: Ionization and Coulomb explosion of xenon clusters by intense, few-cycle laser pulses

Modelling dications in the diurnal ionosphere of Venus

Theoretical Investigations of the Electronic and Nuclear Dynamics of Molecules in Intense Laser Fields: Quantum Mechanical Wave Packet Approaches

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