J. Labat

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.

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.

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.

ON THE STARK WIDTH REGULARITIES IN THE SINGLY IONIZED SPECTRA

The existence of the Stark width dependence on the upper-level ionization potential of the quantum transition have been presented for the sixteen types of transitions in spectras of nine singly ionized atoms: C II, N II, O II, F II, Ne II, P II, S II, Cl II and Ar II. On the basis of established regularities the Stark width values of 43 spectral lines, not measured or calculated before, have been predicted. Critical analysis of the existing experimental Stark width data is also given.

Stark widths and shifts of SnI, HgII, HgIII and PbII spectral lines

Stark widths and shifts of neutral and ionized heavy atom spectral lines have been measured and calculated. The Stark parameters of three SnI (284.0, 286.3 and 303.4 nm), five HgII (226.2, 398.4, 222.5, 615.0 and 326.4 nm), two PbII (220.4 and 438.6 nm) and one HgIII (235.4 nm) spectral lines were measured for the first time except the Stark widths of one HgII (398.4 nm) and one PbII (438.6 nm) line. Stark width values for a number of corresponding transitions were calculated on the bases of semiclassical and semiempirical formulae.

Stark width and shift of singly-ionized tin spectral lines

Stark widths and shifts of six singly-ionized tin spectral lines have been measured in a pulsed linear arc plasma in SF6, at 33000 K electron temperature and 0.96 × 1023 m−3 electron density, and compared with existing experimental results.

Stark-broadening regularities of lithium-like and sodium-like isoelectronic sequences

The Stark width (w) of spectral lines of multiply ionized atoms as a function of the upper-level ionization potential (I), the net core charge (z) and the electron temperature (T), was found to be of the form: w=az2T−1/2I−b normalized to 1×1023 m−3 electron density for a given transition array. Coefficientsa andb are independent of the upper-level ionization potential, the net core charge, the electron temperature and density. This paper proves the validity of this equation for Stark widths in domains of electron densities of (0.5–1.5)×1023 m−3 and temperatures of 20 000–80 000 K. The reduced Stark width (wT1/2/z2) dependence on the inverse value of upper-level ionization potential is represented by a linear trend (in log-log scale) of the experimental and relevant theoretical results within maximal scatter of less than ±30%. For a givenns-np transition array, this trend is equally applicable to spectral lines of (i) successive ionization stages of the same atom and (ii) ions of isoelectronic sequences of the second and third periods of the periodic system. It is also shown that coefficientsa andb depend on the energy state of the electron emitter core. Using the obtained trends, one can quite successfully predict the Stark width of spectral lines of corresponding transitions that have not yet been measured.

Contribution to studies on hollow cathode discharges

The electron temperature measured in a hollow cathode by the optogalvanic method, discloses the fact that at lower gas pressure (order 100 Pa) its value is of the order of 0.1 eV, not sufficient to sustain the discharge. The role of high energy electrons, that are responsible for maintaining of the discharge in such cases, was investigated. A simple Monte Carlo simulation, based on the concept of beam electrons, containing only the most important processes has been applied in order to obtain the population of the two lowest excited states of neon. At the same time, the energy distribution of high energy electrons was obtained. The results of calculated densities of 1s5 and 1s4 neon atom states were found to be in a favourable agreement with values measured by the laser induced fluorescence method.

Measured stark widths of BI, BII, BIII and Nal spectral lines

Stark widths of six spectral lines from neutral and multiple ionized boron and three spectral lines from neutral sodium spectra have been measured in a pulsed linear arc plasma. All the measurements have been done in the electron density range of 1.66 × 1023–2.55 × 2023m-3 and in the electron temperature range of 40 000-50 000 K. Some of these experimental values are compared with existing theoretical data.

Stark broadening regularities along a homologous sequence of the second group in the periodic system

Abstract The existence of a Stark-width dependence on the upper-level ionization potential has been demonstrated for the homologous sequence of the second group of the elements in the periodic system for three types of transitions in the case of singly-ionized atoms. Equality has been noted for the reduced Stark widths of ionic spectral lines in the A and B subgroups of the fourth, fifth and sixth periods. Using the observed trends, we have predicted Stark widths for the BeII, SrII and RaII spectral lines that have not yet been measured or calculated.