Double-slit photoelectron interference in strong-field ionization of the neon dimer

TL;DR

The authors show the double-slit interference effect in the strong-field ionization of neon dimers by employing COLTRIMS method to record the momentum distribution of the photoelectrons in the molecular frame.

Abstract

Wave-particle duality is an inherent peculiarity of the quantum world. The double-slit experiment has been frequently used for understanding different aspects of this fundamental concept. The occurrence of interference rests on the lack of which-way information and on the absence of decoherence mechanisms, which could scramble the wave fronts. In this letter, we report on the observation of two-center interference in the molecular frame photoelectron momentum distribution upon ionization of the neon dimer by a strong laser field. Postselection of ions, which were measured in coincidence with electrons, allowed choosing the symmetry of the continuum electronic wave function, leading to observation of both, gerade and ungerade, types of interference.

Figures (4)

• Figure 1: a) Relevant potential curves of the neutral and singly charged neon dimer. Potential curves are taken from${ }^{22}$. Spin-orbit splitting was simulated by separating asymptotic parts of the I and II curves by 100 meV . b) Kinetic energy release (KER) for the $\mathrm{Ne}^{+}-\mathrm{Ne}^{0}$ dissociation channel. Two ionization pathways leading to $\mathrm{Ne}^{+}$$\mathrm{Ne}^{0}$ dissociation are shown by red (indirect) and blue (direct) arrows. The inset shows the electron momentum distribution in the molecular frame, when both pathways are considered. The red side of the sketched
• Figure 2: Photoelectron momentum distributions in the molecular frame as defined in the method section: a) and d) - measured, b) and e) are the same as distributions in a) and d) but normalized to the monomer distribution in order to remove ionization weighting of the final momenta. c) and f) are simulated spectra with two coherently superimposed atomic distributions. Red side of the sketched molecule defines the momentum direction of the measured neon ion.
• Figure 3: Normalized photoelectron momentum distributions of$\mathrm{Ne}_{2}$ projected to the molecular axis for the direct (a) and indirect (b) ionization pathways. The spectra were generated by selecting only the events, where the dimer axis lies within +/-20 degrees to the polarization direction of the laser field. Original spectra are divided by the corresponding spectrum of the monomer in order to remove the ionization weighting.
• Figure 4: Dependence of the two-center interference for the direct ionization pathway on the internuclear distance encoded in the momentum of the ion. a) experiment, b) classical simulation using ground state wave function and the II(1/2)g potential curve shown in Fig. 1. Each row is normalized to its maximum value in order to remove weighting caused by the ground state probability distribution. In the simulation the electron momentum distribution was weighted by a Gaussian distribution according to tunneling theory.