# Angle-Resolved Spectra of the Direct Above-Threshold Ionization of Diatomic Molecule in IR+XUV laser field

## TL;DR

This paper investigates the angle-resolved spectra of direct above-threshold ionization in diatomic molecules under IR+XUV laser fields, revealing interference patterns and structural imaging capabilities without recollision effects.

## Contribution

It introduces a frequency-domain quantum electrodynamics approach to analyze ATI spectra and provides a simple formula to predict interference fringes for any molecular alignment.

## Key findings

- XUV laser enhances ionization probability and electron kinetic energy
- IR laser broadens the electron energy distribution
- Spectra can image molecular structure without recollision

## Abstract

The direct above-threshold ionization (ATI) of diatomic molecules in linearly-polarized infrared and extreme ultraviolet (IR+XUV) laser fields is investigated by the frequency-domain theory based on the nonperturbative quantum electrodynamics. The destructive interference fringes on the angle-resolved ATI spectra, which are closely related to the molecular structure, can be well fitted by a simple predictive formula for any alignment of the molecular axis. By comparing the direct ATI spectra for monochromatic and two-color laser fields, we found that the XUV laser field can both raise the ionization probability and the kinetic energy of the ionized electron, while the IR laser field can broaden the energy distribution of the ionized electron. Our results demonstrate that, by using IR+XUV two-color laser fields, the angle-resolved spectra of the direct ATI can image the structural information of molecules without considering the recollision process of the ionized electron.