Inter- and intracycle interference effects in strong-field dissociative ionization

Abstract

We theoretically study dissociative ionization of H + 2 exposed to strong linearly polarized few-cycle visible, near-infrared and near-midinfrared laser pulses. We find rich energy-sharing structures in the combined electron and nuclear kinetic energy spectra with features that are a priori at odds with simple energy conservation arguments. We explain the structures as interferences between wave packets released during different optical cycles, and during the same optical cycle, respectively. Both inter-and intracycle interference structures are clearly visible in the joint energy spectra. The shapes of the interference structures depend on the dynamics leading to the double continuum, and carry sub-femtosecond information.

Photon Energy Deposition in Strong-Field Single Ionization of Multielectron Molecules

“…As shown in Fig. 1(d intracycle interferences of the released electron in the strongfield ionization of H 2 þ affects the slope of the resulting electron-nuclear JES structure [27]. As we will discuss below, for CO these two distinct JES structures also correlate with the electron releasing from different orbitals and photon-assisted coupling of various electronic states in the ionization and dissociation processes.…”

“…The excess photon energy over the ionization threshold is not only deposited to the outgoing electron, but also transferred to the heavy nuclei via their correlated interactions. As compared to the H 2 þ [20][21][22][23][24][25][26][27] or H 2 [28], the light may directly interact with the nuclei for the heteronuclear diatomic molecule having a permanent dipole. However, for CO the dipole moments of the nuclei and the three highest occupied molecular orbitals (HOMOs) are estimated to be 0.0028 (nuclei), 0.4486 (HOMO), 0.2909 (HOMO-1), and 0.3232 Debye (HOMO-2), respectively.…”

“…A quantitative reproduction of the slope requires a precise description of the complex ionization dynamics of the multielectron molecule, which is beyond our current numerical model. As compared to the H 2 þ [20][21][22][23][24][25][26][27] and H 2 [28], the JES for the dissociative ionization of CO shows several common and different characters. First of all, JES is a general process in the dissociative ionization of molecules, which is a strong proof of electron-nuclei coupling in ultrafast chemical reactions.…”

“…Until recently, the electron-nuclear sharing of the absorbed photon energy in strong-field multiphoton single ionization of molecules was revealed for the simplest one-or twoelectron systems of H 2 þ [20][21][22][23][24][25][26][27] and H 2 [28]. On the other hand, the recent experiments showed negligible photon energy sharing between the emitted electrons and ions in double ionization of a polyatomic hydrocarbon molecule [29].…”

Comparison between the analysis of the asymptotic wavepacket and the associated flux for the calculation of kinetic‐energy‐releases function

“…The latter can be regarded as a time‐dependent analysis, in which the dissociation wavepacket is propagated through a reference point in the asymptotic region and during the propagation, the kinetic‐energy‐dependent flux at the reference point is cumulated to obtain the final distribution probability (see, for example, Refs. ). For simplicity, we term the former “projection method” and the latter “flux method.” To the best of our knowledge, the comparison between the two methods is seldom reported.…”