K-shell X-Ray Emission from Lithium-like Nitrogen N v

We present laboratory measurements of n = 3 -> n = 1 N v X-ray emission lines situated near 26 & Aring;. The lines are excited by electron-impact collisions and are shown to reach a combined intensity of about a fifth of the combined strong N v 1s2s2p(2)P(1/2,3/2) -> 1s(2)2s(2)S(1/2) resonance lines, commonly labeled q and r, at 29.4 & Aring;. In addition, we present new experimental data for the wavelength of the blended q and r lines at 29.4 & Aring;, as well as for that of the blended inner-shell-excited N v lines u and v at 30.0 & Aring;. All of these collisional N v lines need to be included in astrophysical emission models in order to properly account for flux from N v in the soft X-ray region. The measured wavelengths provide benchmarks for testing atomic structure calculations and excellent agreement is found with our calculations using the many-body perturbation theory method. We provide a complete listing of the N v energy levels with valence electrons in the n = 2, 3, and 4 shells calculated with this approach. The experimental and theoretical data, thus, provide accurate rest-frame wavelengths needed for velocity determinations based on high-resolution absorption features in spectra of warm absorbers in active galactic nuclei and other astrophysical objects.