The abundance of nitrogen in the Earth's atmosphere and, also, the large number of multiply ionized nitrogen spectral lines in hot stars spectra makes these lines of great importance for diagnostics purposes. Knowledge of the Stark width and shift dependence upon the electron temperature (T) in the plasma is, also, of importance for testing their theoretical predictions based on various approaches.
A number of experimental and theoretical papers have dealt with Stark broadening and shift of singly (NII), doubly (NIII) and triply (NIV) ionized nitrogen spectral lines (Fuhr & Lesage 1993 and references therein; Konjevic & Wiese 1976; Konjevic et al. 1984; Konjevic & Wiese 1990). In spite of this, only few publications have been devoted to the experimental and theoretical investigation of the Stark shift values of ionized nitrogen spectral lines. No experimental Stark shift data exists for NIV spectral lines, to the knowledge of the authors.
The aim of this paper is to provide some new
data on several Stark shift and width of multiply ionized nitrogen spectral
lines at 54 000 K electron temperature. We have measured Stark shifts (d) and
Stark HWHM (half-width at half intensity maximum, w) of eight NII, seven NIII
and five NIV spectral lines belonging to 
and 
transitions. Stark
shifts of 463.054 nm, 464.309 nm and 399.500 nm of NII, 486.72 nm and 486.718
nm of NIII, as well of 347.87 nm, 348.30 nm, 348.49 nm, 374.77 nm and 405.78
nm of NIV spectral lines have not been measured before. The same hold also for
the Stark width value of the 348.30 nm NIV line. Stark shift of the 298.36 nm
spectral line is the first data for the multiplet No. 25UV in NIII spectra.
The measured values of Stark widths and shifts were compared to the existing
theoretical predictions based on the semi-classical, semi-empirical
and modified
semi-empirical approaches initiated
by Dimitrijevic & Konjevic (1980, 1981a,b).