Manipulation of the recombination channels and isolated attosecond pulse generation from HeH²⁺ with multicycle combined field

Abstract

We present a method to manipulate the recombination channels in harmonic emission from HeH2+ via combing a multicycle trapezoidal laser field and a static electric field. By solving the time-dependent Schrödinger equation, we find that the positive peak intensity can steer the electron localization by controlling the electron transfer at the time of laser polarization direction antiparallel to the permanent dipole of HeH2+. With appropriate laser parameters, the recombination channels originating from the nucleus He2+ are effectively controlled by enhancing electron localization around the nucleus H+. Additionally, an isolated 48-as pulse can be obtained by superposing proper harmonics. Time-frequency maps, electronic wave packet probability density and a laser dressed picture of the Coulomb potential are adopted to provide the underlying physical mechanism.

Monitoring the electron dynamics of the excited state via higher-order spectral minimum

“…The time-dependent wave function is advanced using the standard second-order split-operator method 26 , 27 . In the numerical simulation, the converged numerical parameters are as follows: the grid ranges from 1.00 a.u.…”

Laser control on molecular harmonic emission and isolated attosecond pulse generation

“…, HeH 2+ , H 2 , HeH + etc) attracts lots of attention in optical physics [1,2] and leads to many new interesting phenomena. Such as, the bond softening and hardening [3,4]; the asymmetric ionization and dissociation channels [5,6]; the charge-resonance-enhanced-ionization [7,8]; the dissociative ionization [9], the kinetic-energy spectra of the dissociation and the Coulomb explosion channels [10]; the above-threshold dissociation (ATD) and the above-threshold ionization (ATI) [11,12]; the molecular high-order harmonic generation (MHHG) [13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”

“…Yuan and Bandrauk [16,17] theoretically investigated the generations of the circularly or elliptically polarized harmonics in H 2 + and obtained an isolated circularly polarized attosecond pulse with the combination of a few cycle elliptically polarized laser pulse and a terahertz field. Bian et al [18], Miao et al [19], Feng et al [20] and Chen et al [21] theoretically investigate the multi-channel harmonic emission from the asymmetric molecule HeH 2+ . Lan et al [22] investigate to the destructive interference structure on the MHHG.…”

Quantum Path Selection and Isolated-Attosecond-Pulse Generation of H 2 + with an Intense Laser Pulse and a Static Field

“…As we know, the electron wave packet probability distribution of H + 2 molecule ions strongly depends on the combined Coulomb and laser field potential. [15,16] By adjusting the intensity of static field, the short path is successfully selected with the decrease of the number of electrons contributing to the long path. Both the classical electron trajectory and quantum time-frequency distribution are calculated to illustrate the physical mechanism.…”

“…As indicated in the previous research, the electron-nuclear or electron wave packet distribution is closely related to the variation of the potential well when the molecular ion interacts with the laser field. [15,16] Along with the interaction of the laser pulse and molecule, this symmetric potential will be distorted and the electron distribution is bound to change. Based on the above discussion, we know that the energy peak P 1 (P 3 ) is contributed by the electrons ionized around the laser peak A (A ′ ), i.e., around 𝑡 = 2.0 o.c.…”