Stark broadening and regularities of prominent spectral lines of multiply ionized chlorine and fluorine.

Abstract

Stark widths of six Cl ii, eight Cl iii, three Cl iv, and two F iii spectra lines and Stark shifts of six Cl ii and eight Cl iii spectral lines have been measured in a linear-pinch discharge plasma and compared with available experimental and theoretical data. The electron density determined by single-wavelength laser interferometry using the visible 632.8-nm transition of a He-Ne laser was 1.97\ifmmode\times\else\texttimes\fi{}${10}^{23}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$. The electron temperature of 27 000 K was determined from the Boltzmann slope of several Cl ii spectral lines and from the intensity ratios of several Cl ii to Cl iii spectral lines. Since the majority of Cl ii, Cl iii, and Cl iv spectral lines investigated originate from 4s-4p transition arrays, the Stark-width (w) dependence on the upper-level ionization potential (I) of corresponding lines has been established and discussed both within one stage of ionization of chlorine and within several stages of ionization of chlorine and fluorine (including neutral chlorine and fluorine).Simultaneously, the Stark-width dependence was found on the net charge (z) of the emitter core acting upon the optical electron undergoing transition. Similarly, Stark-width data obtained for F iii spectral lines originating from the 3s-3p transition array, together with other authors' experimental and theoretical data of F i, F ii, and F iii spectral lines originating from the same transition arrays, were used to discuss the features of these dependences. The dependences are of the forms w=${\mathrm{AI}}^{\mathrm{\ensuremath{-}}a}$ (within one ionization stage of chlorine or fluorine) and w=${\mathrm{Bz}}^{2}$${I}^{\mathrm{\ensuremath{-}}b}$ (among several ionization stages of chlorine or fluorine), where A, a, B, and b are constants independent of the ionization potential. The trends obtained were used to predict the Stark width of uninvestigated spectral lines originating from the given 4s-4p (chlorine) and 3s-3p (fluorine) transitions with an accuracy better than 30%.