Selective enhancement of resonant multiphoton ionization with strong laser fields

TL;DR

This study investigates how specific laser intensities can selectively enhance resonant multiphoton ionization in xenon atoms, revealing a double-ring structure in photoelectron spectra linked to Rydberg state resonances.

Contribution

It demonstrates the intensity-dependent selective enhancement of resonant multiphoton ionization involving Rydberg states using velocity-map imaging.

Findings

Double-ring structures appear at specific laser intensities.

Resonant multiphoton ionization involves multiple Rydberg states.

Selective enhancement of ionization via Rydberg states is achievable.

Abstract

High-resolution photoelectron momentum distributions of Xe atoms ionized by 800-nm linearly polarized laser fields have been traced at intensities from 1.1*1013 to 3.5*1013W/cm2 using velocity-map imaging techniques. At certain laser intensities, the momentum spectrum exhibits a distinct double-ring structure for low-order above-threshold ionization, which appears to be absent at lower or higher laser intensities. By investigating the intensity-resolved photoelectron energy spectrum, we find that this double-ring structure originates from resonant multiphoton ionization involving multiple Rydberg states of atoms. Varying the laser intensity, we can selectively enhance the resonant multiphoton ionization through certain atomic Rydberg states. The photoelectron angular distributions of multiphoton resonance are also investigated for the low-order above-threshold ionization.