Investigation of electron localization in harmonic emission from asymmetric molecular ion

Abstract

We theoretically investigate the electron localization around two nuclei in harmonic emission from asymmetric molecular ion. The results show that the ionization process of electron localized around one nucleus competes with its transfer process to the other nucleus. By increasing the initial vibrational level, more electrons localized around the nucleus D+ tend to transfer to the nucleus He2+ so that the ionizations of electrons localized around the nucleus He2+ increase. In this case, the difference in harmonic efficiency between HeH2+ and HeD2+ decreases while the difference in harmonic spectral structure increases. The evident minimum can be observed in the harmonic spectrum of HeH2+ compared with that in the spectral structure of HeD2+, which is due to the strong interference of multiple recombination channels originating from two nuclei. Time-dependent nuclear probability density, electron-nuclear probability density, double-well model, and time-frequency maps are presented to explain the underlying mechanisms.

Carrier envelope phase effect on the spatial distribution of high-order harmonic generation in asymmetric molecule

“…[5] On the one hand, much effort has been done to the HHG of the symmetric molecules, such as N 2 , [6,7] H + 2 , [8][9][10] and CO 2 . [11] On the other hand, the investigation of the asymmetric molecule also attracts a great deal of attention, such as CO, [12] HCl, [13] HeH 2+ , [14,15] which have the permanent dipole of the molecule (PDM) and the multiple centers because of the symmetry breaking.…”

Controlling the contributions to high-order harmonic generation from different nuclei of N 2 with an orthogonally polarized two-color laser field

“…[1][2][3][4] High-order harmonic radiation has been a powerful tool to generate attosecond pulses [5][6][7][8] and coherent soft xray source, [9] to probe ultrafast electronic dynamics, [10,11] and to reveal structures of molecular orbitals. [12,13] The basic understanding of the formation for attosecond pulse train in HHG has been provided by a semi-classical three-step model. [14][15][16] An electron in an atom is ionized by tunneling through the effective potential barrier, then it oscillates freely under the drive of the electronic field, and after sign reversal of the field, it may recollide with its parent ion, emitting a harmonic photon simultaneously whose energy corresponds to the sum of ionization energy and the kinetic energy of the electron.…”

High-order harmonic generation of N 2 molecule in two-color circularly polarized laser fields

“…The potential applications of HHG from molecules such as real-time observation, molecular orbital tomographic imaging and reconstruction have attracted a lot of attention. [10][11][12][13][14][15] The effect of intramolecular interference was investigated theoretically in H + 2 and H 2 molecules by numerical solution of the Schrödinger equation or S-matrix method. [16][17][18] In 2005, Itatani et al [19] realized to control the high order harmonic generation process by changing the alignment of molecules, they also accomplished the highest occupied molecular orbital (HOMO) of the N 2 molecule.…”