Experimental Stark-broadening studies of the NI multiplet $\mathsf{(^{1}D) 3s^{2}D - (^{1}D)3p^{2}P^{o}}$ at 7904.5 �

Abstract

Experimental Stark-broadening studies of the NI multiplet \((^{1}{\rm D})3s\) \(^{2}{\rm D} - (^{1}{\rm D})3p\) \(^{2}{\rm P}^{\rm o}\) are reported. Line shape measurements were performed using a wall-stabilized arc operated at atmospheric pressure in helium with small amounts of nitrogen and hydrogen. The radiation of the plasma emitted from nearly homogeneous plasma layers in end-on direction was measured using a grating spectrometer equipped with a charge-coupled device (CCD) detector. The arc current was varied from 35 to 50 A in order to obtain different plasma conditions (electron densities and temperatures). The so-called j(x) profiles of Griem, convoluted with the corresponding Doppler and apparatus profiles were fitted to the experimental data sets. In this way the Stark broadening parameters: the electron impact shifts (d e ) and widths (w e ) as well as ion-broadening asymmetry (A) for the investigated NI multiplet have been determined.