Ionization of Methane in Strong and Ultrastrong Relativistic Fields

Palaniyappan, S.; Mitchell, R. E.; Sauer, Robert; Ghebregziabher, Isaac; White, Samantha; DeCamp, Matthew F.; Walker, Barry

doi:10.1103/physrevlett.100.183001

Cited by 38 publications

(37 citation statements)

References 28 publications

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“…Various processes and phenomena have been investigated, including high-order harmonic generation [3], creation of attosecond pulses [4], control of molecular dissociation [5], ultrafast imaging [6], electron tunneling and diffraction [7], and Coulomb explosion [8,9]. Highly energetic dissociation of a molecule or solid due to multiple ionization, known as the Coulomb explosion, is a particularly interesting process because it exposes the key physical mechanisms associated with the electron and nuclear dynamics and ionization [9][10][11][12][13]. Once the laser strips electrons from the molecule, the remaining positively charged structure can explode, creating a molecular plasma cloud.…”

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confidence: 99%

Strong laser-pulse-driven ionization and Coulomb explosion of hydrocarbon molecules

et al. 2012

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Field ionization and Coulomb explosion of small hydrocarbon molecules driven by intense laser pulses are studied in a combined theoretical and experimental framework. The spectra of ejected protons calculated by the time-dependent density functional approach are in good agreement with the experimental data. The results of the simulations give detailed insight into the correlated electron and nuclear dynamics and complement the experiment with a time-dependent physical picture. It is demonstrated that the Coulomb explosion in the studied molecular systems is a sudden, all-at-once fragmentation where the ionization step is followed by a simultaneous ejection of the charged fragments. [7], and Coulomb explosion [8,9]. Highly energetic dissociation of a molecule or solid due to multiple ionization, known as the Coulomb explosion, is a particularly interesting process because it exposes the key physical mechanisms associated with the electron and nuclear dynamics and ionization [9][10][11][12][13]. Once the laser strips electrons from the molecule, the remaining positively charged structure can explode, creating a molecular plasma cloud. Coulomb explosion can be used to generate bright keV x-ray photons [14,15], highly energetic electrons [16], and for imaging [17][18][19].The strong-field ionization and fragmentation of hydrocarbon molecules is a prototypical example of the Coulomb explosion of polyatomic molecules, and it has been the subject of several experiments [9,11,[20][21][22][23]]. An important quantity measured in these experiments is the kinetic energy distribution of the protons ejected during the fragmentation. Proton energies in excess of 30 eV at only very moderate peak intensities of the driving laser pulses have been reported for both large [11] and small hydrocarbon molecules [9]. The proton kinetic cutoff energies depend sensitively on the laser intensity and saturate at intensities that depend on the molecular species [9,11]. Earlier, this behavior was attributed to the creation of a long-lived charge localization state [11]. A more recent experiment [9], in contrast, suggested that the high kinetic proton energies originate from Coulomb explosions from a high molecular charge state. It was suggested [9] that a multibond version of the enhanced ionization process [24,25] is responsible for reaching the observed high charge states, from which the protons are ejected simultaneously in a concerted Coulomb explosion process resulting in complete molecular fragmentations. A recent theoretical study [26] using a one-dimensional model of acetylene, C 2 H 2 , confirms the proposed ionization mechanism leading to the high charge states, but it did not investigate the fragmentation dynamics. While the experimental approaches allow the study of important aspects of the Coulomb explosion of molecules by analyzing the properties of the resulting fragments, they do not provide a complete, dynamical description of the internal mechanism taking place during the fragmentation.In this work, the intense laser puls...

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Strong laser-pulse-driven ionization and Coulomb explosion of hydrocarbon molecules

et al. 2012

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“…Much of the work on molecular systems has focused on diatomic homo-and hetero-nuclear molecules in the strong field [25,26] and lower charge state dissociative ionization channels in polyatomic molecules [27][28][29]. For molecules in ultrahigh intensities, highly charged fragment ionization has been observed to be like that of the atomic ion [30].…”

Section: Introductionmentioning

confidence: 99%

Molecular ionization of chloromethane in strong fields: nearest neighbor gateway to highly charged ions

Grugan

Ekanayake

White

et al. 2018

J. Phys. B: At. Mol. Opt. Phys.

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The strong and ultrastrong field-molecule interaction is a complex, many-body process involving multiple ionization processes. We present ion yields and molecular fragment energies for the ionization of chloromethane (CH 3 Cl) in a laser field with intensities spanning from 10 14 to 10 17 W cm −2 . As the laser intensity increases, ionization of CH 3 Cl is observed to pass from molecular tunneling, to enhanced ionization (EI), to an atomic-like response. The energy spectra of the ions show no dependence on the intensity and has its source in dissociative molecular ionization. A classical model of an aligned C-Cl ion is used to model the interaction. Following an initial molecular ionization process, our results show EI is a driving influence in the formation of low charge states until ionization become atomic-like and involves tightly bound ion states whose ionization is unaffected by nearest neighbor ions of similar ion charge.

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“…Sim ple analytical expressions for the angular and energy distributions of direct photoelectrons in the relativistic regime have been obtained in [25] by means of the adi abatic Landau-Dykhne approximation. Relativisti cally strong laser fields have recently been employed in experimental studies on ionization of atoms [26] and molecules [27].…”

Section: Introductionmentioning

confidence: 99%

Relativistic nonperturbative above-threshold phenomena in strong laser fields

Müller¹,

Hatsagortsyan²,

Ruf³

et al. 2009

Laser Phys.

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Abstract-Relativistic features of various nonperturbative above threshold phenomena in strong laser fields are discussed and compared. This includes above threshold ionization of multiply charged ions as well as pair production in an ultrastrong laser wave, superimposed with either a nuclear Coulomb field or another coun terpropagating laser wave. For the probability of above threshold pair production, a new scaling relation is given. Particular attention is paid to similarities among these processes, regarding the energy and angular spectra of the particles as well as the total reaction rates.

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Ionization of Methane in Strong and Ultrastrong Relativistic Fields

Cited by 38 publications

References 28 publications

Strong laser-pulse-driven ionization and Coulomb explosion of hydrocarbon molecules

Strong laser-pulse-driven ionization and Coulomb explosion of hydrocarbon molecules

Molecular ionization of chloromethane in strong fields: nearest neighbor gateway to highly charged ions

Relativistic nonperturbative above-threshold phenomena in strong laser fields

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