Effect of Nuclear Motion on Molecular High-Order Harmonics and on Generation of Attosecond Pulses in Intense Laser Pulses

Abstract

We calculate harmonic spectra and shapes of attosecond-pulse trains using numerical solutions of Non-Born-Oppenheimer time-dependent Shrödinger equation for 1D H2 molecules in an intense laser pulse. A very strong signature of nuclear motion is seen in the time profiles of high-order harmonics. In general the nuclear motion shortens the part of the attosecond-pulse train originating from the first electron contribution, but it may enhance the second electron contribution for longer pulses. The shape of time profiles of harmonics can thus be used for monitoring the nuclear motion.

Isolated-attosecond-pulse generation due to the nuclear dynamics of H2+in a multicycle midinfrared laser field

“…Here the moving electron and nuclei are allowed to be calculated using complete one-dimensional (1D) TDSE. Such a simplified 1D H 2 + model has been verified by many previous studies [19,23,26,27]. The 1D TDSE is written as (e =h = m e = 1 in atomic units (a.u.…”

“…As is well known, when R increases to intermediate-to-large internuclear separations (5 < R < 12 a.u. ), CREI in the H 2 + molecule is remarkable [16,19]. While for the H atom, the attosecond pulses are generated every half-cycle resulting in the creation of attosecond pulse trains, as shown in Fig.…”

“…Molecules in the * zhinan zeng@mail.siom.ac.cn † ruxinli@mail.shcnc.ac.cn strong-field process were investigated earlier at fixed internuclear distance from the Born-Oppenheimer approximation, which ignores the couplings of the electronic and nuclear wave packet. Recently, non-Born-Oppenheimer (NBO) timedependent Schrödinger equation (TDSE) simulations have revealed a variety of unique nonlinear responses, such as allowing the shortening of the trains of generated attosecond pulses [19] and monitoring electron-nuclear dynamics on an attosecond time scale since the harmonic signal can be modified by the nuclear motion [20,21].…”

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

“…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].…”

Stability of the time-dependent configuration-interaction-singles method in the attosecond and strong-field regimes: A study of basis sets and absorption methods

“…HHG is the most dominating method for producing attosecond pulses [9]. HHG has also been used to probe orbital structure [10][11][12][13] and electronic [14,15] and nuclear motion [16][17][18][19]. Furthermore, multi-orbital [13,20,21] and electronic correlation effects [11,22,23] can play an important role and in turn can be studied with HHG and other strong-field processes.…”