Multiple Photoionization of the Rare Gases

Abstract
The photoionization yield or average charge produced per photon absorbed by Ne, Ar, Kr, and Xe has been measured from the threshold of double photoionization to 107 eV. The probability of double ionization is zero at threshold for the rare gases. For Ar, Kr, and Xe double ionization increases rapidly giving an abundance of 16 to 30% at 20 eV beyond the double-ionization threshold. In this region double ionization is constant or increasing slowly. At the threshold for triple ionization the average charge per photon increases rapidly.