Orientation-dependent dissociative ionization of H2 in strong elliptic laser fields: Modification of the release time through molecular orientation

Abstract

We investigate the photoelectron angular emission distributions obtained by strong field dissociative ionization of H2 using cold target recoil ion momentum spectroscopy. In case of employing laser light with an ellipticity close to 0.9 and an intensity of 1.0 × 10 14 W/cm 2 , we find that the most probable release-time of the electron does not generally coincide with the time when the laser field maximizes. The release-time is affected by the molecular orientation. In addition, we observe that the width of the release-time distribution depends on molecular orientation. We attribute this observation to a two-center-interference confirming a prediction by Serov et al. [1].

Probing Molecular Frame Wigner Time Delay and Electron Wavepacket Phase Structure of CO Molecule

“…If neglecting the Coulomb interaction after ionization, the electron emission angle is determined by the vector potential at the release time. One can directly obtain the release-time variation with respect to the laser field peak from the change of the emission angle of photoelectrons [24,25]. We then obtain the corresponding ionizationtime shift ~±593 attosecond (as) for the SB1 peak and ~± 629 as for the ATI2 peak with respect to the instant when the CoRTC field maximizes.…”

“…Recently, the attosecond holographic angular streaking scheme using two-color bicircular fields (ω + 2ω) has been widely used to explore time-resolved photoemission dynamics in atomic multiphoton ionization [16][17][18][19][20][21], such as probing the phase and amplitude of emitting wave packets [16], and measuring the time delay of spin-orbit coupled electronic states [20]. In contrast to atomic photoionization, molecular frame measurements of complex molecules show that the spatial distribution of molecular orbitals can result in the displacement of rescattering wavepacket [22], orientation-dependent electron phase distribution [23], and modulation of the releasing time of photoelectrons [24,25]. Due to the anisotropy of the long-range ionic potential in molecules, the photoelectron interference patterns are distorted.…”

Angular dependence of the Wigner time delay upon tunnel ionization of H2

“…It is important to note that the Wigner time delay and the most probable electron release time 18 , 48 – 50 are different quantities. In typical experiments that use the attoclock-setup the square of the electronic wave function in final momentum, space is measured 18 , 19 , 50 – 52 .…”

“…S1 ). Second, we analyze the interference patterns for a given value of β which makes our analysis insensitive to the dependence of the ionization rate on the tunneling direction in the molecular frame 48 , 53 . Therefore, HASE allows for the measurement of the phase of the initial wave packet in momentum space at the tunnel exit, just as the attoclock setup can be used to measure the amplitude of the initial wave packet in momentum space at the tunnel exit.…”

Alignment dependence of photoelectron momentum distributions for diatomic molecules N$_2$ in strong elliptical laser fields

“…On the other hand, photoelectron momentum distributions (PMDs) in strong elliptically-polarized laser fields with large ellipticity have been widely used in probing the tunneling dynamics of atoms and molecules, and the relevant probing procedure has been termed as attoclock [40,41]. In the attoclock experiments, the brightest part of PMD, which is associated with the mostprobable emission angle of the photoelectron, is generally used as the observable characteristic quantity through which the key dynamical information of the studied system is deduced [40][41][42][43][44][45][46][47][48][49][50][51][52]. For example, with this characteristic quantity, the intriguing issues of tunneling time [40,41,43,45,[47][48][49][50][51], tunneling exit [42], nonadiabatic effects in tunneling [44], excited tunneling [46], permanent-dipole effects in tunneling [52], etc., have been explored deeply.…”