We present a (1+1)-dimensional quantum model designed to describe nonsequential double ionization (NSDI) in homonuclear diatomic molecules exposed to strong linearly polarized laser fields. Extending the restricted-geometry framework previously developed for atomic systems by Eckhardt and Sacha, our approach captures key features of NSDI, including the characteristic knee structure in double ionization yields. Despite its simplifying assumptions, the model shows good agreement with experimental data and proves particularly suitable for systems with
σ-type orbital symmetry. It offers a computationally efficient tool for exploring multi-electron dynamics in molecular systems.
Rydberg-state excitation of atoms in strong infrared laser fields provides a new complementary aspect of the perspective of atom--strong field interactions. In this article, we perform an experimental and theoretical study on the corresponding process of diatomic molecules,
N2 and
O2. We show that neutral molecules can also survive strong 800-nm laser fields in high Rydberg states, while their behavior is remarkably different in comparison with their companion atoms, Ar and Xe. The Rydberg excitation of
N2 generally behaves similarly to Ar, while that of
O2 is more significantly suppressed than the ionization compared to Xe in a high intensity region, which can be understood in the frame of a semiclassical picture, together with their different structures of molecular orbitals. However, distinct quantum features in the Rydberg excitation processes that are apparently beyond the semiclassical picture have been identified, i.e., the less suppressed probability of
O2 at low intensity and the oscillation behavior of the ratio between
N2 and Ar, indicating that our understanding of the relevant physics is still far from complete.
The authors present a combined experimental and theoretical study of strong-field-induced electronic coherences in argon and molecular nitrogen ions as a step towards strong-field coherent control in molecular chemistry. They find that nonsequential double ionization in the low-intensity region of the focal volume can reduce the visibility of coherence generated by two-pulse sequential ionization, and quantify the importance of pulse shape and spectral characteristics for isolating the desired coherence signals.
We study the control of ionization dynamics of aligned
N2 and
O2 molecules in orthogonally polarized two-color (OTC) fields and calculate the photoelectron momentum distributions of molecules by solving the time-dependent Schr\"odinger equation and with a semiclassical model. In contrast with that of atoms in the OTC field, we show that the photoelectron momentum distribution is essentially dependent on the molecular outmost orbital, the alignment angle, and the phase of the OTC field. We illustrate the controlling of the molecular frame photoelectron angular distributions and the temporal and spatial double-slit interference effect for strong-field ionization of
N2 molecules. For
O2 molecules, it is shown that the ionization wave packets are splitting. The temporal and spatial double-slit interference effect is always present for
O2, which is not able to be turned off using the OTC field. This work would have implications for probing molecular structures with a two-color synthesized laser field.
Non-sequential double ionization (NSDI) is a strong-field process involving the correlated emission of two electrons. This thesis proposes an analog quantum simulator to study NSDI in a helium atom, using ultracold trapped atoms to represent electrons. The core potential is replaced by an optical trap created by a laser. Rydberg atoms, with their strong long-range interactions, are ideal for simulating attosecond phenomena. A numerical simulation is conducted to observe the correlated two-electron momentum components after a laser pulse is applied.
Young type interference effect for quantum particles can be seen in the cross sections for electron impact ionization of diatomic molecules. Interference factor is determined for description of interference effects in the ionization cross sections. Although such structures are observed for small diatomic molecules, larger molecules are less discussed in the recent works. Interference effects are already observed in the ionization cross sections of H2 and N2 molecules by electron impact. Similar effects expected to be seen on cross sections of larger diatomic molecules. The aim of this work, is to further highlight the possibility of interference effects may be seen also in the ionization cross sections of larger diatomic molecules and also discuss the structure of interference factor. This study is a preliminary study for the experiments can be carried to investigate interference effects in the cross sections of larger homonuclear diatomic molecules.