The first Au III Stark widths

The shapes of 12 doubly ionized gold (Au III) spectral lines have been measured in the laboratory helium plasma at about 16 600 K electron temperature and 7.4×¹⁰²² m⁻³$7.4\times {10}^{22}{\text{ m}}^{\mathrm{-3}}$ electron density. At mentioned plasma conditions the Stark broadening has been found as the dominant mechanism in the Au III line shape formation. Here presented data are the first reported values for Stark widths related to the Au III lines. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in helium with gold atoms, as impurities, evaporated from gold cylindrical plates located in the homogeneous part of the discharge, providing conditions free of self-absorption.     

Stark broadening in the Sb III spectrum

The shapes of nine doubly ionized antimony (Sb III) spectral lines have been obtained in the laboratory helium plasma at 17 500 K electron temperature and electron density of . Measured line profiles are of a Voigt type. At the mentioned plasma conditions the Stark broadening has been found as the dominant mechanism in the Sb III line shapes formation. Using a deconvolution procedure the Lorentz (Stark) FWHM (Full-Width at Half of the Maximal intensity, W) have been obtained. Our measured Sb III Stark widths are the first data in the literature. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in helium with antimony atoms, as impurities. They were evaporated from the thin antimony layer, deposited on the silver cylindrical plates, located in the homogenous part of the discharge. This plasma source ensures good conditions for the generation of the doubly ionized antimony atoms in the helium plasma due to atomic processes concerning helium metastables.     

On the Cd III spectrum in a pulsed helium discharge

On the basis of the spectral line intensity relaxation during the plasma decay, fifty six spectral lines between 219 nm and 330 nm in the cadmium (Cd) spectrum were identified as Cd III (doubly ionized) or Cd IV (triply ionized) lines. The measured Stark widths of twelve, the most intense spectral lines around 315±15 nm with well defined profiles, are presented. Investigated spectral lines originate from the high lying energy levels, not classified up to now. A linear low-pressure pulsed arc was used as an optically thin plasma source. A pulsed discharge was produced in a pyrex discharge tube. Helium was chosen as the carrier gas. The cadmium atoms were sputtered from the thin cadmium cylindrical plates located in the homogeneous axial part of the discharge tube. The helium plasma was operated at electron temperatures up to 19 000 K and 1.1 × 10²³ m^-3 electron density. The stepwise ionization processes via the high lying singly ionized (Cd II) energy levels, populated well due to the Penning and charge exchange effects, provide high density of the Cd III (and Cd IV) ions in our helium plasma. The temporal evolutions of the spectral line intensities were monitored using a spectrograph and an ICCD camera as a highly sensitive detection system.     

Measurements of electron density and Stark width of neutral helium lines in a helium arc plasma

Electron densities in an atmospheric helium arc plasma have been measured with the Stark broadening parameters of helium spectral lines. The spatially distributed radiation intensities are converted to plasma emission coefficients at every wavelength by means of Abel inversion. From the inverted profiles of He I lines of 4713 ?, 5016 ?, and 6678 ? electron density has been calculated, which ranges from 0.5 ×10¹⁶ to 4 ×10¹⁶ cm^-3 for a helium arc with current 200 A. Stark widths of He I lines of 3889 ? and 7065 ? are determined based on the measurements and compared with existing data.     

Stark broadening parameters of the 381.96 nm He I line

Stark width (W) and shift (d) of the neutral helium (He I) 381.96 nm spectral line in the high lying 2p-6d transition has been measured in the optically thin linear, low-pressure, pulsed arc discharge operated in the helium at 50 000 K electron temperature and 6.1 x 10²² m^-3 electron density. These values are the first experimentally obtained W and d related to this line. Unfortunately, comparison with theoretical results is not possible due to the fact that only one existing theoretical calculations has been done at a 10¹⁹ m^-3 electron density only. We have found negative line shift (toward the blue) that agree well with existing theoretical predictions.Received: 19 February 2004, Published online: 4 May 2004PACS: 52.70.Kz Optical (ultraviolet, visible, infrared) measurements - 32.70.Cs Oscillator strengths, lifetimes, transition moments - 32.70.-n Intensities and shapes of atomic spectral lines     

On the Stark broadening of the He I 447.1 nm spectral line

Characteristics of the Stark broadened and overlapping 447.1 nm He I spectral line and its forbidden 447.0 nm components have been measured at electron densities between 4.4×10²² m^-3 and 8.2×10²² m^-3 and electron temperatures between 18 000 K and 33 000 K in plasmas created in five various discharge conditions using the low pressure pulsed arc as an optically thin plasma source operated in helium-nitrogen-oxygen gas mixture. Good agreement was found among our measured line characteristics and their existing calculated values, based on the quasistatic approximation. Possible influence of the singly ionized oxygen impurity atoms (O II) on the intensity values of the dip between allowed and forbidden components was found that can explain the disagreement among some existing experimental and calculated line characteristics data, at higher electron temperatures and densities. On the basis of the observed asymmetry of the 447.1 nm spectral line profile we have obtained the ion contribution parameter at 10²² m^-3 electron density and 8 000 K electron temperature. Received 20 February 2001 and Received in final form 25 April 2001     

The first measured Mn I Stark widths

The shapes of the astrophysically interesting neutral manganese (Mn I) resonance spectral lines (403.075, 403.306, 403.448, 279.481, 279.826 and 280.108 nm) have been observed together with six other prominent Mn I lines in the laboratory helium plasma at a 47 000 K electron temperature and electron density. With these plasma parameters the Stark broadening has been found to be an important mechanism in the Mn I line shape formation. Our measured Mn I Stark widths (W) are the first data in the literature. Stark widths are compared with line hyperfine structure splittings (Δ_hfs). At above mentioned helium plasma conditions the line broadening due to hyperfine structure splitting of the lines is less than that of the Stark and Doppler broadening for the case of the Mn I lines under investigation. We estimate that at electron densities below and electron temperatures below 4000 K the components in the hyperfine structure play an important role in the mentioned Mn I line shape formation.     

Measurement of electric field strengths in a waveguide by means of the dynamic Stark effect in hydrogen and neutral helium spectral lines

The dynamic Stark effect of the spectral lines H_β and of the neutral helium lines λ=402.6 nm (2³ P ⁰−5³ D) and λ=438.8 nm (2¹ P ⁰−5¹ D) emitted from a discharge tube was used for probing rf electric fields in a transverse waveguide. Calculations accounting for the pertubation of the atomic states by strong unidirectional fields prove to be suitable in order to interprete the main experimental results. If the waveguide is terminated with a metallic reflector and the plasma in the discharge tube becomes overdense—then representing a slightly permeable mirror—a resonant enhancement of the electric field strength may be achieved by tuning. This enhancement is well recognizable in the spectral line contours.     

大气压等离子体炬电子密度的光谱诊断

利用空心针-板放电装置产生了大气压等离子体炬,采用光谱法测量了其内部及表面的电子密度. 向空心针中通入氩气,在大气环境中产生了长度为1cm的等离子体炬.实验分别测量了Hα谱线和ArⅠ(696.54nm)谱线,通过反卷积方法分离出其相应的Stark展宽,并由此计算了电子密度.结果发现,采用Hα谱线和ArⅠ(696.54nm)谱线Stark展宽计算得到的等离子体的电子密度分别为1.0×10¹⁵cm^－3和3.78×10^{15关键词： 等离子体炬 电子密度 气体温度 Stark展宽}     

On the use of relative line intensities of forbidden and allowed components of several HeI lines for electric field measurements

In this Letter we propose a method for electric field measurements based on intensity ratio of forbidden and allowed helium lines. HeI 402.6 nm, HeI 447.1 nm, and HeI 492.1 lines and their forbidden components are used for the measurement of electric field strength in the cathode region of the abnormal glow discharge in helium-hydrogen mixture. Electric filed strength was independently determined using polarization spectroscopy of Hβ line and then compared with electric filed strength obtained from relative intensity of HeI forbidden and allowed lines.     

The He I 706.52 nm line shape characteristics in the plasma diagnostics

On the basis of the precisely recorded 706.52 nm He I line shape we have obtained the basic plasma parameters i.e. electron temperature (T) and electron density (N) using our new line deconvolution procedure in the case of five various plasmas created in a linear, low-pressure, pulsed arc discharge. Plasma parameters have been also measured using independent experimental diagnostical techniques. Excellent agreement was found among the two sets of the obtained parameters. This enables our deconvolution procedure to recommendation for plasma diagnostical purposes, especially in astrophysics where direct measurements of the plasma parameters (T and N) are not possible. Besides, on the basis of the observed asymmetry of the Stark broadened line profile we have obtained its ion broadening parameter (A) caused by influence of the ion microfield to the line broadening mechanism and also the influence of the ion dynamic effect (D) to the line shape. Our A and D parameters represent the first data obtained experimentally using the line profile deconvolution procedure. We have found stronger influence of the ion contribution to the 706.52 nm He I line profile than the existing theoretical approximations estimate. This can be important for plasma modeling or for diagnostics. Received 30 October 2002 Published online 15 April 2003 RID="a" ID="a"e-mail: vladimir@ff.bg.ac.yu     

Stark broadening of S(III) and S(IV) lines

Measurements of the Stark widths of doubly and triply ionized sulfur lines were made in a low pressure, pulsed arc plasma of electron density 5.1 × 10¹⁶ cm^-3 at an electron temperature of 28, 500°K. The experimental S(III) and S(IV) Stark-profile halfwidths were compared with calculated values obtained with Griem's semiempirical and approximate semiclassical approach. The experimental results agree better with the semiclassical results.     

Controlled Stark shifts in Er-doped crystalline and amorphous waveguides for quantum state storage

We present measurements of the linear Stark effect on the ⁴I_15/2 → ⁴I_13/2 transition in an Er³⁺-doped proton-exchanged LiNbO₃ crystalline waveguide and an Er³⁺-doped silicate fiber. The measurements were made using spectral hole burning techniques at temperatures below 4 K. We measured an effective Stark coefficient (Δμ_eχ)/(h) = 25 ± 1 kHz/V cm⁻¹ in the crystalline waveguide and  kHz/V cm⁻¹ in the silicate fiber. These results confirm the potential of erbium-doped waveguides for quantum state storage based on controlled reversible inhomogeneous broadening.     

Experimental transition probabilities in N III,N IV and N V spectra

We have obtained transition probabilities (Einstein's A values) of thirteen transitions in doubly (N III), six in triply (N IV) and two in four times (N V) ionized nitrogen spectra belonging to the 3s-3p and 3p-3d transitions using a relative line intensity ratio (RLIR) technique. The linear low-pressure pulsed arc was used as an optically thin plasma source operated at 51 400 K electron temperature and 2.2×10²³ m^-3 electron density in nitrogen plasma. Our A values are compared to recent theoretical and experimental data. Received 18 December 2001 / Received in final form 29 January 2002 Published online 28 June 2002     

Stark broadening measurements of some N(II) and N(III) lines

The Stark widths of seventeen N(II) and ten N(III) spectral lines, emitted from a wall-stabilized arc plasma with electron densities in the range 0.9-2.9 × 10¹⁷ cm^-3, were measured. The arc was run with a 1:1N₂:He mixture, and the electron densities were determined from the Stark widths of He(I) 5876 and 6678 A. The Stark widths of the N lines were found to scale approximately linearly with electron density.     

Linewidth studies on Cd+ 636.0 nm and 537.8 nm lines excited in a He-Cd hollow cathode discharge

Hollow cathode (HC) lasers usually operate in a single axial mode without any optical selection. This is attributed to the large homogeneous linewidth of the gain curve due to the relatively high filling pressure of these lasers. Collisional and Doppler broadening (Δν_C and Δν_D) of the Cd⁺ 636 nm and Cd⁺ 538 nm lines (laser transitions of the HeCd⁺ laser) excited in a HC discharge tube were determined using a Fabry–Perot interferometer technique. It was found that in the pressure range 7–25 mbar Δν_D was nearly constant, while, as expected, Δν_C increased linearly with pressure. The broadening constants were α(636 nm)= (47±2) MHz/mbarand α(538 nm)=(11.8±0.5) MHz/mbar. The first constant is large enough to explain single-mode operation of the red HeCd⁺ laser; but in the case of the green laser, the exact reason for the single-mode operation remained unclear. Received: 23 November 2000 / Revised version: 30 March 2001 / Published online: 7 June 2001     

Experimental Stark broadening studies of the CI transition 3s1P1o ? 3p1S0 at 833.5 nm

Experimental Stark broadening studies of the infrared CI transition 3s ¹ P ₁ ^o − 3p ¹ S ₀ at 833.5 nm are reported for the first time. A high-current wall-stabilized arc, operated in a mixture of helium, argon, carbon dioxide and hydrogen, was applied as the plasma source. Radiation emitted from homogeneous and optically thin plasma layers was analyzed. Stark broadening studies of the selected CI transition and the hydrogen Balmer β line were performed. As expected from theoretical considerations, the CI line width depends linearly on the electron density of the plasma. Applying theoretical Stark broadening data for the H _gb line, the measured Stark widths of the CI line were calibrated for the purpose of electron density determination in low temperature plasmas.     

Electrical and optical characterization of pulsed plasma of N<Subscript>2</Subscript>–H<Subscript>2</Subscript>

This paper considers the electrical and optical characterization of glow discharge pulsed plasma in N₂/H₂ gas mixtures at a pressures range between 0.5 and 4.0 Torr and discharge current between 0.2 and 0.6 A. Electron temperature and ion density measurements were performed employing a double Langmuir probe. They were found to increase rapidly as the H₂ percentage in the mixture was increased up to 20%. This increase slows down as the H₂ percentage in the gas mixture was increased above 20% at the same pressure. Emission spectroscopy was employed to observe emission from the pulsed plasma of a steady-state electric discharge. The discharge mainly emits within the range 280–500 nm. The emission consists of N₂ (C-X) 316, 336, 358 nm narrow peaks and a broad band with a maximum at λ_max = 427 nm. Also lines of N₂, N₂ ⁺ and NH excited states were observed. All lines and bands have their maximum intensity at the discharge current of 0.417 A. The intensities of the main bands and spectral lines are determined as functions of the total pressure and discharge current. Agreement with other theoretical and experimental groups was established.     

Determination of the Electron Density in an Argon Laser Plasma by Spectroscopy of the Hydrogen Hα and Hβ Lines

From measurements of the H_α and H_β spectral line profiles in a plasma, a method is developed which allows to separate the contributions of Doppler and Stark broadening. This method is superior to the deconvolution of Voigt profiles, in particular, when the lines are of low intensity. The electron density in the plasma can be calculated from the Stark broadening. An example is the low pressure (p ≈ 1 hPa) arc discharge of argon ion lasers which is characteristised by electron densities of approximately 10¹⁴ cm^?3 at heavy particle temperatures of about 10⁴ K. These plasma parameters lead to a broadening of the Balmer H_α and H_β spectral lines of hydrogen, which has a low concentration within the discharge area. The spectral lines are broadened due to the electron density dependent Stark effect and the temperature responsive Doppler effect. The results are consistent with predictions of the argon ion laser modelling.     

Kinetics of luminescence induced by sputtering metallic cadmium by a pulsed fast electron beam in helium

Results of an experimental study of the kinetics of luminescence observed when a metallic cadmium foil is bombarded in a helium medium by a 3-ns pulsed beam of 150-keV fast electrons are reported. The foil was irradiated at gas pressures from 76 to 2280 Torr. At a foil temperature of T = 240° C, the de-excitation time of the Beitler levels of the Cd II ion was measured as a function of the buffer gas pressure and the constant of collision quenching of the 5s22D_5/2 level of Cd II by He atoms was determined as k ≈ 3 × 10^-29 cm⁶/s. The experimental data were compared with calculations performed for the gas—vapor mixture in order to find the fraction of excited Cd II ions in the 5s²2D_5/2 state produced directly as a result of sputtering of metallic cadmium by high-energy electrons and by components of the helium plasma. At a helium buffer gas pressure of P ≤ 2.5 atm and a temperature of the cadmium target of T = 240° C, the value of this quantity was found to be α = 0.28 + 0.23P (where P is the helium pressure in atmospheres).