A. Srećković

Measured Stark widths and shifts of singly ionized oxygen spectral lines in lower multiplets

Abstract Stark widths and shifts of nine O II lines were measured at electron temperature 54 000 K and electron density 2.8 × 1023m−3 in a linear, low-pressure, pulsed arc operated in a nitrogen-oxygen mixture. Our data are compared with values calculated on the basis of semiclassical approximation.

Stark broadening parameters in C II, C III and C IV spectra

Stark widths and shifts of nine singly charged (C II), one doubly charged (C III) and two triply charged (C IV) prominent carbon spectral lines, have been measured at electron temperatures between 13 800 and 20 500 K and electron densities between 0.91×1023 and 1.96×1023 m-3, using a linear low-pressure pulsed arc, as an optically thin plasma source, operated in CO2. Measured Stark broadening parameters have been compared with the existing experimental and theoretical data.

Stark shifts and transition probabilities in Si III and Si IV spectra

Stark shifts of nine doubly charged (Si III)and six triply charged (Si IV) siliconion spectral lines have been measured in a linear, low-pressure, pulsed arc operated in O2 and SF6 discharges. Si III Stark shift values have been also calculated using the semiclassical perturbation formalism (SCPF) for electrons, protons and helium ions as perturbers. Transition probabilities of the spontaneous emission (Einsteins A values) of nine Si III transitions have been obtained using the relative line intensity ratio (RLIR) method, not applied before in Si III spectrum, and, also, calculated using the Coulomb approximation method. The measured Si IV shift and some calculated Si III shift values present the first published data in this field.

Stark broadening and regularities of ionized neon and argon spectral lines

Stark widths of five Ne III, five Ne IV, one Ar III and nine ArIV spectral lines have been measured in a linear-pinch discharge plasma. The results were compared with existing experimental and theoretical results, and used to establish several types of regularities. Electron densities determined with single-wavelength laser interferometry were 2.18·1023 m−3 and 2.80·1023 m−3 in neon and argon plasma, respectively. The electron temperatures determined from the Boltzmann slope of several Ne III spectral lines, and ratios of Ne III to Ne IV or Ar III to Ar IV spectral lines were 59 000 K and 42 000 K in neon and argon plasma, respectively. The investigated spectral lines originate predominantly, from 3s–3p and 3s′–3p′ Ne III and Ne IV, and from 4s–4p and 4s′–4p′ Ar III and Ar IV transition arrays. The emphasis is on the Stark width (θ) dependence on the upper level ionization potential (I), the emitter core net charge (z) and electron temperature (T) for a given electron density. This dependence was found to be of the form: θ=az2T−1/2I−b, wherea andb are constants within(i) several stages of ionization of neon or argon and(ii) within nitrogen like (NI, O II, F III and Ne IV) 3s–3p or phosphorus like (P I, S II, Cl III and Ar IV) 4s–4p transition arrays. The established overall trends were used to predict the Stark widths of univestigated spectral lines originating from the given transition arrays.

Mg II spectral line broadening in helium, oxygen and argon-helium plasmas

Stark widths (W) and shifts (d) of the astrophysically very important six (279.0777, 279.5528, 279.7998, 280.2705, 292.8633 and 293.6510 nm) singly ionized magnesium (Mg II) spectral lines in helium, oxygen and argon-helium plasmas have been measured at electron temperatures between 30 000 and 52 300 K and electron densities between 1.2 × 10 23 and 1.65 × 10 23 m −3 . They are the first experimental results obtained at electron temperatures higher than 20 000 K. A linear, low-pressure, pulsed arc has been used as an optically thin plasma source. The magnesium atoms, as impurities in the driving gases, have been introduced by erosion from the pure magnesium bands fixed on the discharge electrodes. Our measured Stark width and shift values have been compared to the existing experimental and theoretical data. We have found a good agreement with W and d values calculated by the semiclassical perturbation formalism (SCPF).

Stark broadening and shift of neutral and singly-ionized mercury lines

Abstract Stark widths and shifts of four Hg I and two Hg II spectral lines have been measured in a linear, low-pressure, pulsed arc operated in a nitrogen-mercury vapor mixture. All of the experimental data were recorded at electron densities up to 4.2 x 1022m-3 and an electron temperature of 37,000 K. The experimental Hg I and Hg II Stark widths and shifts are compared with values calculated on the basis of semiclassical and semiempirical formulae.

Experimental transition probabilities and Stark shifts in O III and O IV spectra

On the basis of the relative line intensity ratio (RLIR) method transition probability values of the spontaneous emis- sion (Einsteins A values) of 41 astrophysically important transitions (in 15 multiplets) in the doubly (O III) and 7 transitions (in 5 multiplets) in triply (O IV) ionized oxygen spectra have been obtained relative to the reference A values related to the 326.085 nm O III and 340.355 nm O IV, most intensive transitions in the O III and O IV spectra. Fourteen of the investigated O III lines belong to the cascades in the astrophysically important Bowen fluorescence mechanism. Most of the O III transition probability values are the first data obtained experimentally using the RLIR method. Stark shift values (d) of the mentioned lines are also measured. Twenty three of them were not known and represent the first data in this field. Our A and d values are compared to available experimental and theoretical data. A linear, low-pressure, pulsed arc was used as an optically thin plasma source operated in oxygen discharge at a 42 000 K electron temperature and 1.65 × 10 23 m −3 electron density.

Stark broadening in O III spectrum

The Stark widths and shifts of 7 doubly ionized oxygen (O III) spectral lines, in five multiplets, have been measured at electron densities between 1.66 10 23 m -3 and 2.80 10 23 m -3 and electron temperatures between 17 000 K and 54 000 K in a linear pulsed-arc discharge in N 2 + O 2 and CO 2 plasmas. The above mentioned species have been calculated using the semiclassical perturbation formalism. Our measured and calculated Stark width and shift values have been compared to the existing calculated and experimental data.

Stark broadening and shift of singly and doubly ionized fluorine spectral lines

Stark widths and shifts of eight singly and one doubly ionized florine spectral lines have been measured in a pulsed linear are plasma in SF6 at two different electron densities and temperatures, and compared with existing theoretical results. Our data and those of other authors were used to investigate some regularities of Stark broadening within homologous group of halogene elements.

Stark broadening and shift of singly-ionized argon spectral lines in higher multiplets

Abstract Stark-widths and -shifts of 25 singly-ionized spectral lines, mostly higher multiplets, have been measured and compared with existing experimental and theoretical results. A linear pinch discharge was used as a plasma source. Electron densities determined with single wavelength laser interferometry and using the visible transition of an He-Ne laser were (0.86-2.12) × 1023 m-3. An electron temperature of 26,000 K was derived from the Boltzmann slope of several Ar II spectral lines and from intensity ratios of Ar III spectral lines to several Ar II spectral lines. Our data and those of other authors were used to investigate the nature of the Stark-broadening dependence on the following: (i) upper-level ionization potential of the spectral line belonging to the 4p-4d transition array and (ii) electron temperature. The established trend is used to predict Stark-widths of as yet uninvestigated spectral lines originating from the given transition array.