$K$-Shell X-Ray Spectroscopy of Atomic Nitrogen

Absolute $K$-shell photoionization cross sections for atomic nitrogen have been obtained from both experiment and state-of-the-art theoretical techniques. Because of the difficulty of creating a target of neutral atomic nitrogen, no high-resolution $K$-edge spectroscopy measurements have been reported for this important atom. Interplay between theory and experiment enabled identification and characterization of the strong $1s\to np$ resonance features throughout the threshold region. An experimental value of $409.64\pm 0.02\mathrm{eV}$ was determined for the $K$-shell binding energy.

Figure 1

Partial cross sections for photoionization of atomic nitrogen to (a) ${\mathrm{N}}^{+}$, (b) ${\mathrm{N}}^{+2}$, and (c) ${\mathrm{N}}^{+3}$. Figures (d) and (e) are experimental results from a mixture of atomic/molecular nitrogen and molecular nitrogen resulting in ${\mathrm{N}}^{+2}$.

Figure 2

Atomic-nitrogen total photoionization cross section. Theoretical results were convoluted with a 60 meV FWHM Gaussian to simulate experiment. Experimental results include molecular components between 400 and 406 eV.