Ionization-induced Susceptibility by Nearly-free Electrons in Gases Influenced by the Coulomb Potential

TL;DR

This paper investigates how the Coulomb potential affects the plasma susceptibility in photoionized gases, revealing significant enhancements in the real part and unique contributions to the imaginary part due to nearly-free electrons.

Contribution

It demonstrates the substantial impact of Coulomb potential on plasma susceptibility, highlighting the role of nearly-free electrons and their dependence on intensity and wavelength.

Findings

Real part of susceptibility is over ten times larger with Coulomb potential.

Long-range Coulomb potential adds a new contribution to the imaginary part.

Susceptibility varies with intensity and wavelength of the incident light.

Abstract

In the present paper we study the influence of the Coulomb potential on the real and imaginary parts of the plasma-induced susceptibility in a photoionized gas. We show that the real part of the susceptibility is more than one order of magnitude larger due to the action of a Coulomb potential. Surprisingly, the long-range Coulomb potential of the atomic core leads to an additional contribution to the imaginary part of the susceptibility which has no counterpart in the case of a short-range potential. We demonstrate that the origin of this behavior are electrons in states very close to the continuum (nearly-free electrons), and analyze the dependence of the susceptibility on the intensity and wavelengths.