Experimental ion contribution to the Stark broadening of neutral-nitrogen spectral lines in the vacuum uv

The ion contribution to the Stark broadening, as described by a suitably defined asymmetry function $A_L$, was investigated from the asymmetry behavior of the vacuum-uv spectral lines of N I at 119.955 nm (${}_{}{}^4{}_{}{}^{}P\to {}_{}{}^4{}_{}{}^{}S_{}^0{}_{}{}^{}$), 141.194 nm (${}_{}{}^2{}_{}{}^{}D\to {}_{}{}^2{}_{}{}^{}P_{}^0{}_{}{}^{}$), 149.467 nm (${}_{}{}^2{}_{}{}^{}P\to {}_{}{}^2{}_{}{}^{}D_{}^0{}_{}{}^{}$), and 174.273 nm (${}_{}{}^2{}_{}{}^{}P\to {}_{}{}^2{}_{}{}^{}P_{}^0{}_{}{}^{}$). The line radiation, which was emitted under controlled optical depths, was generated in a dense equilibrium plasma (wall-stabilized arc; electron number density $4.0\times {10}^{22} {\mathrm{m}}^{-3\mathrm{}}\le n_e\le 3.7\times {10}^{23} {\mathrm{m}}^{-3\mathrm{}}$; temperature $11000\le T\le 15000$ K). Deviations between experimental asymmetry functions of this study and those calculated from recently published data by Griem, have been found for the wings of N I 119.955 nm (normalized wavelength distance from the line center $\frac{\Delta \lambda }{\Delta {\lambda }_{\frac{1}{2}}}\ge 1$; $A_L^{\mathrm{Griem}}-A_L^{\mathrm{this}\mathrm{study}}\le 0.1$). For N I 141.194, N I 149.467, and N I 174.273 nm, the asymmetry functions based on line profiles calculated by Griem are in agreement with the asymmetry functions of this study within the given uncertainties. In addition, Stark-width and Stark-shift parameters were experimentally determined for the N I spectrum between 118 and 180 nm. The Stark-width parameters calculated by Griem and by Wilson and Nicolet agreed with the data of this study within ± 20%. Only for N I 131.054 and N I 132.663 nm did the Stark-width parameters calculated by Wilson and Nicolet deviate from the corresponding values of this study by approximately + 31%. The calculated Stark-shift parameters of Wilson and Nicolet, however, were considerably higher than the corresponding data of this study (maximum deviation + 78%), whereas the Stark-shift parameters calculated by Griem showed smaller deviations from the data of this study (maximum deviation + 49%).