Dielectronic recombination of ${\mathrm{N}}^{4+}$

The dielectronic recombination spectrum of ${\mathrm{N}}^{4+}$ has been measured with high resolution and accuracy. The ${1s}^{2}2p5l$ resonances in the energy range $0–1.6\mathrm{eV}$ were studied in detail. The experimental spectrum is compared with the results from four different calculations. An almost perfect agreement between the experiment and a calculation which combines relativistic many-body perturbation theory and complex rotation is found. The calculation provides accurate spectroscopic data for all fifty ${1s}^{2}2p5l$ states. The literature value for the ${1s}^{2}2p5s$ ${}^{1}P$ energy level is found to be off by more than 0.1 eV.