Probing nuclear vibration using high-order harmonic generation

Nguyen, Ngoc-Ty; Hoang, Van-Hung; Le, Van-Hoang

doi:10.1103/physreva.88.023824

Cited by 17 publications

(8 citation statements)

References 22 publications

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“…Interestingly, this trend of ionization probability differs from that reported by Nguyen et al . 61 , who found maximum intensity in HHG (proportional to the ionization probability) near the time when the internuclear separation is at the equilibrium value, and the nuclei are moving closer. Because the chosen probe-pulse duration was longer in their calculations (FWHM of approximately 14 fs, i.e., the full duration of approximately 38 fs), the nuclear velocity had a strong influence on HHG.…”

Section: Resultsmentioning

confidence: 99%

Dissociation and Ionization of Quasi-Periodically Vibrating H2+ in Intense Few-Cycle Mid-Infrared Laser Fields

Jiang

Yuan

et al. 2017

Sci Rep

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Using quantum mechanics calculations, we theoretically study the dissociation and ionization dynamics of the hydrogen-molecule ion in strong laser fields. Having prepared the nuclear wave packet of H2+ in a specific vibrational state, a pump laser is used to produce a vibrational excitation, leading to quasi-periodical vibration without ionization. Then, a time-delayed few-cycle laser is applied to trigger the dissociation or ionization of H2+. Both the time delay and the intensity of the probe laser alter the competition between dissociation and ionization. We also explore the dependence of kinetic-energy release spectra of fragments on the time delay, showing that the channels of above-threshold dissociation and below-threshold dissociation are opened and closed periodically. Also, dissociation from different channels is influenced by nuclear motion. The dissociation mechanism has been described in detail using the Floquet picture. This work provides a useful method for steering the electronic and nuclear dynamics of diatomic molecules in intense laser fields.

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Section: Resultsmentioning

confidence: 99%

Dissociation and Ionization of Quasi-Periodically Vibrating H2+ in Intense Few-Cycle Mid-Infrared Laser Fields

Jiang

Yuan

et al. 2017

Sci Rep

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“…Nonetheless, most of the non-BO numerical studies of HHG still concern the dynamics of simple, oneand two-electron diatomics (H 2 [65][66][67][68], H 2 + [64,66,[68][69][70][71][72][73][74][75][76][77][78][79][80], HeH 2+ [81]), usually with the additional approximations of the reduced dimensionality [66][67][68][69][70][71][72][73][74]77,80,81] or special field polarizations [64,75,76,78,79]. Some attempts at extending the theory of nuclear dynamics in HHG to more general non-BO systems have been reported in the literature [65,[82][83][84][85][86][87][88][89][90][91]…”

Section: Published By the American Physical Society Under The Terms Omentioning

confidence: 99%

Full-dimensional treatment of short-time vibronic dynamics in a molecular high-order-harmonic-generation process in methane

Patchkovskii

Schuurman

2017

Phys. Rev. A

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We present derivation and implementation of the multiconfigurational strong-field approximation with Gaussian nuclear wave packets (MC-SFA-GWP)-a version of the molecular strong-field approximation which treats all electronic and nuclear degrees of freedom, including their correlations, quantum mechanically. The technique allows realistic simulation of high-order-harmonic emission in polyatomic molecules without invoking reduced-dimensionality models for the nuclear motion or the electronic structure. We use MC-SFA-GWP to model isotope effects in high-order-harmonic-generation (HHG) spectroscopy of methane. The HHG emission in this molecule transiently involves the strongly vibronically coupled 2 F 2 electronic state of the CH 4 + cation. We show that the isotopic HHG ratio in methane contains signatures of (a) field-free vibronic dynamics at the conical intersection (CI); (b) resonant features in the recombination cross sections; (c) laser-driven bound-state dynamics; as well as (d) the well-known short-time Gaussian decay of the emission. We assign the intrinsic vibronic feature (a) to a relatively long-lived ( 4 fs) vibronic wave packet of the singly excited ν 4 (t 2 ) and ν 2 (e) vibrational modes, strongly coupled to the components of the 2 F 2 electronic state. We demonstrate that these physical effects differ in their dependence on the wavelength, intensity, and duration of the driving pulse, allowing them to be disentangled. We thus show that HHG spectroscopy provides a versatile tool for exploring both conical intersections and resonant features in photorecombination matrix elements in the regime not easily accessible with other techniques.

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“…It is shown in these investigations that in the tunnelling regime, higher vibrational states in the ground state H + 2 give rise to more efficient HOHG when the laser field is parallel to the molecular axis [12,13]. In another work, effects of the nuclear velocity on the HOHG produced from the ground state H + 2 have been studied for two parallel and perpendicular orientations of the laser field polarization [14]. The relation between electronic wavepacket expansion and internuclear distance on the HOHG [15] and dependence of multi-photon ionization and HOHG phenomena on different internuclear distances [16] are also investigated.…”

Section: Introductionmentioning

confidence: 99%

High-order harmonic generation by H$_2^+$ in super-intense xuv ultrashort laser pulses

Sabzyan¹,

Ahmadi²,

Vafaee³

2014

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

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Dynamics of the two-dimensional H + 2 under 30-and 40-cycle xuv (45 and 90 nm) laser pulses is investigated by numerical solution of the time-dependent Schrödinger equation beyond the dipole and Born-Oppenheimer approximations for two orientations (θ = 0 • and θ = 90 • referenced to the molecular axis) of the laser polarization. Dynamics of the electron and nuclei are treated in quantum and classical approaches, respectively. The ground, first and second excited states of H + 2 are considered as initial states for different laser field intensities in the range of (4×10 16 -4×10 19 W cm −2 ). For parallel orientation (θ = 0 • ), a negligibly small difference is seen for high-order harmonic generation (HOHG) spectra obtained with the dipole and non-dipole Hamiltonians for all three electronic states. While, for the perpendicular orientation (θ = 90 • ), non-dipole forces attenuate the HOHG spectra for the initial ground and the second excited states. For the initial first excited state and orientation θ = 90 • , the motion of nuclei considerably increases the HOHG yield within the dipole approximation, but decreases it partially beyond dipole approximation. It is shown that contribution of the motion of nuclei to the HOHG yield depends on the extent of the increase in the separation between nuclei.

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Probing nuclear vibration using high-order harmonic generation

Cited by 17 publications

References 22 publications

Dissociation and Ionization of Quasi-Periodically Vibrating H2+ in Intense Few-Cycle Mid-Infrared Laser Fields

Dissociation and Ionization of Quasi-Periodically Vibrating H2+ in Intense Few-Cycle Mid-Infrared Laser Fields

Full-dimensional treatment of short-time vibronic dynamics in a molecular high-order-harmonic-generation process in methane

High-order harmonic generation by H$_2^+$ in super-intense xuv ultrashort laser pulses

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