Single- and double-photoionization cross sections of atomic nitrogen from threshold to 31 Å

The relative photoionization cross section of atomic nitrogen for the production of singly and doubly charged ions has been measured from 44.3 to 275 Å and from 520 to 852 Å. The results have been made absolute by normalization to one-half of the molecular nitrogen cross section at short wavelengths. The smoothed atomic nitrogen cross sections σ can be accurately represented, at short wavelengths, by the equation σ(Mb)=3.67×${10}^4$ ${\mathit{E}}^{\mathrm{-}2.3}$ as a function of the photon energy E (eV), thereby allowing the cross sections to be extrapolated to the nitrogen K edge at 31 Å.