Driving-laser wavelength dependence of high-order harmonic generation inH2+molecules

Abstract

The electron-nuclear dynamics of one-dimensional H 2 + molecular high harmonic generation is investigated by numerical integration of the non-Born-Oppenheimer time-dependent Schrödinger equation. It is found that the nuclear motion and electron ionization are more significant for the longer wavelength and the stronger intensity of the driving laser pulse. When the ground-state H 2 + molecule is driven by a short laser pulse (ten optical cycles in the calculations), a strong signature of nuclear motion is seen in the wavelength scaling (800-2000 nm) of harmonic yield, following a λ −(7-8) scaling law at a constant laser intensity. It is attributed to the fast ground-state depletion induced by the strong nuclear motion, when using the long wavelength. Consequently, the wavelength scaling gives an insight into the nuclear dynamics.

Intensity enhancement in the molecular ionization and dissociation dynamics in the presence of noise

“…This 1+1D model has been tested by others [26][27][28][29][30][31] and by ourselves [32], showing a qualitatively agreement with the experimental measurements. Using this model, we carried out a detailed investigation when the diatomic molecular ion (H 2 + ) is irradiated by an intense infrared laser field in combination with a noise field where either a Gaussian white noise or a color noise is considered.…”

“…q is the soft Coulomb potential and a, b (a00.03 and b01.0 [33] in this paper) represent the softening parameters to remove the Coulomb singularity [26,34], the use of which provides an efficient way to obtain realistic numerical results for multiphoton processes [26][27][28]35]. The most important feature of this potential is that at large z it falls off like the true Coulomb potential (a0 b00 is the true Coulomb potential), and it was proved previously that the physical characteristics of this model have allowed realistic investigations of the behavior of a H 2 + ion in a laser field [26,29].…”

Multiconfiguration time-dependent Hartree approach for electron-nuclear correlation in strong laser fields

“…In the present work, we apply the multiconfiguration theory for the first time to the case of coupled electronic and nuclear motion. We use a onedimensional (1D) model H 2 + system [26][27][28][29][30][31][32] to compare exact simulations to the MCTDH method with various numbers of configurations. For laser parameters that are typically used in present-day experiments, we find that a moderate number of single-particle functions is sufficient to provide accurate quantitative results for fragmentation probabilities and HHG spectra.…”

Mapping subcycle electron motion by modulated high-order harmonic generation

“…(13), (14), (18), and (19), we have v 0 ε ln β(τ N ) = θ y0 (τ N ,δ min ), (20) where τ N and δ min are coupled by Eq. (16).…”

“…Destructive interference during HHG in mixed gases has been experimentally used to identify the electron excursion time of a short quantum path [16] and observe the molecular structure [17]. Since the molecular high harmonic signal is modulated by the nuclear vibrational autocorrelation function, HHG can also be used to probe nuclear motion in simple molecules [18][19][20].…”