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.     

Using the van der Waals broadening of the spectral atomic lines to measure the gas temperature of an argon microwave plasma at atmospheric pressure

The ro-vibrational emission spectra of the molecular species are usually used to measure the gas temperature of a discharge at atmospheric pressure. However, under some experimental conditions, it is difficult to detect them. In order to overcome this difficulty and obtain the temperature, there are methods based on the relation between the gas temperature and the van der Waals broadening of argon atomic spectral lines with a Stark contribution negligible. In this work, we propose a method based on this relation but for lines with a Stark broadening comparable with the van der Waals one.     

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=az ² T ^?1/2 I ^?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 (wT ^1/2/z ²) 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.     

Effect of Sample Temperature on Radiation Characteristics of Nanosecond Laser-Induced Soil Plasma

An Nd:YAG single pulse nanosecond laser of 532 nm wavelength with an 8 ns pulse width was projected on the soil samples collected from the campus of Bengbu College under 1 standard atmospheric pressure. Laser-induced breakdown spectroscopy at different sample temperatures was achieved. The intensity and signal-to-noise ratio (SNR) changes of different characteristic spectral lines could be analyzed when the sample temperature changes. The evolution of plasma electron temperature and electron density with the sample temperature was analyzed through Boltzmann oblique line method and Stark broadening method. The cause of the radiation enhancement of laser-induced metal plasma was discussed. Experimental results demonstrated that the spectral intensity, SNR, the electron temperature and electron density of plasma are positively related to the sample temperature, and reach saturation at 100 ℃.     

Experimental determination of the Stark widths of Pb I spectral lines in a laser-induced plasma

Stark widths of 34 spectral lines of Pb I have been measured in a Laser-Induced-Plasma (LIP). The optical emission spectroscopy from a LIP generated by a 10 640 Å radiation, with an irradiance of 1.4 × 10¹⁰ W cm^− 2 on a Sn–Pb target in an atmosphere of argon was analyzed between 1900 and 7000 Å. The Local Thermodynamic Equilibrium (LTE) conditions and plasma homogeneity have been checked. The 34 spectral lines measured in this paper correspond to the transitions n(n = 7, 8)s→6p², n(n = 6, 7)d→6p². The population levels distribution and the corresponding temperatures were obtained using Boltzmann plots. The plasma electron densities were determined using well-known Stark broadening parameters of spectral lines. Special attention was dedicated to the possible self-absorption of the different transitions. Stark broadening parameters of the spectral lines were measured at 2.5 µs after each laser light pulse, where the electron temperature was close to 11 200 K and the electron density to 10¹⁶ cm^− 3. The experimental results obtained have been compared with the experimental values given by other authors.     

Stark shift and broadening of FI and ClI lines

We report measured Stark shifts and widths of neutral flourine and chlorine lines. Wall stabilized arc is used as a plasma source. Electron densities 2–4×10²² m^?3 are determined from the width of theH _β line and electron temperatures 9500–10 000 K from plasma composition data. Experimental results for FI and ClI Stark widths and FI Stark shifts agree within 10% with semiclassical calculations. ClI Stark shifts are systematically smaller for about 20% than theoretical data with the only exception of the line from multiplet no. 15 where the discrepancy goes up to 49%. Results of investigation of similarities and regularities of Stark widths are in agreement with the study of Wiese and Konjevi?. Comparison of experimental Stark shifts shows certain types of regularities.     

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=az ² T ^?1/2 I ^?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.     

Application of laser-induced plasma spectroscopy to the measurement of Stark broadening parameters

In this work, we have studied the main conditions that a laser-induced plasma must fulfill in order to be considered as adequate for the measurement of Stark broadening parameters. We investigated the effect of the temporal window, the self-absorption, the crater size, and the effect of the spatial inhomogeneity on the emission profiles coming from a laser-induced plasma. Starting from the spatially resolved values of the plasma parameters, obtained by emission spectroscopy, the error in the determination of the Stark electron width due to the spatial inhomogeneity has been estimated and, for the present experimental conditions, was found to be lower than 7%. As a test of the method, the Stark electron broadening constant of Fe I 381.58 nm has been measured using the Fe I 538.34 nm emission line as the reference to determine the electron density. The plasma was produced under a controlled atmosphere of argon at atmospheric pressure, on an iron–nickel alloy sample. The emission was collected by a system with high spectral resolution, for different temporal windows after the laser pulse. For time delays between 2.75 and 21 μs, the electron density showed an evolution in the range 2.0–0.13 × 10¹⁷ cm^− 3, while the temperature varied from 11 100 to 7100 K. The representation of the Stark electron width of Fe I 381.58 nm, measured for each temporal window, versus the Stark electron width of the reference line showed a linear behavior with a high correlation coefficient. From the slope of this linear fit and the Stark electron broadening constant of the reference line, the Stark width of Fe I 381.58 nm was obtained to be 1.10 ± 0.07 × 10^− 2 nm for an electron density of 10¹⁷ cm^− 3.     

Stark broadening and shift of neutral iodine lines and regularities for analogous transitions of halogene atoms

We report results of an experimental study of the Stark broadening and shift of fourteen and eight neutral iodine lines, respectively, in a plasma wall stabilized arc. An electron density of about 2 × 10²² m^?3 was determined from the width of H_α line, while an electron temperature about 9300 K was derived from plasma composition data. The agreement within 40% of both experimental Stark widths and shifts with results of simple theoretical approach by Dimitrijevi? and Konjevi? is found. Results of the investigation of similarities of neutral iodine Stark widths are in agreement with the study of Wiese and Konjevi?. Comparison of experimental Stark shift shows similar types of regularities. Comparisons of Stark widths along analogous transitions of halogene atoms show an increase of widths from fluorine to iodine. It has been demonstrated also that Stark shifts for the same transitions show similar behaviour.     

High-level Stark Effect and Spectrum of Spherical Nanometer System

In the electric field and layer-to-layer interaction energy, the law of split-level of high-level Stark effect of spherical nanometer system is explored as well as the frequency of spectrum,intensity and size effect of coefficient of spontaneous radiation. Taking three layers CdS/HgS spherical nanometer system as an example, the influence of the electric field and layer-to-layer interaction energy is explored on Stark effect and spectrum. The results show that in the Stark effect system, the energy level is split based on 1, 3,… , (2n—1), when it is in the electric field only, similar to the hydrogen atoms; and in the electric field and layer-to-layer interaction, it is split based on 1, 4, … , n²; with the quantum transition, the frequency of the spectrum decreases with the increasing size of the system; apart from a few spectral lines, the intensity of most spectral lines will decreased as the size increases; while the coefficient of spontaneous radiation will increase with the increasing size; the electric field will causethe changes of spectrum frequency; its spectrum frequency shift is proportional to the square of the electric field intensity; apart from a few spectral lines, the frequency shift of spectral lines that is caused by the electric field and layer-to-layer interaction will decrease as the size increases; the interaction will make the level of electronic energy level lower slightly (the order of magnitude is between 10^-7—10^-9 eV), the slightly increased spectrum intensity and the slightly increased value of coefficient of spontaneous radiation, but it will not influence the frequency of spectrum, intensity, and the trend that coefficient of spontaneous radiation changes with the size; when the size is smaller, the layer-to-layer interaction effect will be significant.     

Measured Stark widths and shifts of the neutral argon spectral lines in 4s–4p and 4s–4p′ transitions

We investigate the Stark widths (W) and the shift (d), of the seven neutral argon (Ar I) spectral lines from the 4s–4p and 4s–4p′ transitions. The line shapes are measured in a linear, low-pressure, optically thin pulsed arc discharge at about 16 000 K electron temperature (T) and about 7.0 × 10²² m^− 3 electron density (N). The new data separates the electron width (W_e) and ion width W_i from the total Stark width (W_t), as well the separation of electron total Stark shift (d_t) on electron (d_e) and ion (d_i) parts. There are no theoretical predictions for these lines. Comparison to theoretical predictions for other lines within the same multiplets finds that the experimental data exhibits stronger influence by the ion contribution to the measured Ar I line shape. We have also deduced the ion broadening parameters which describe the influence of the ion static (A) and the ion–dynamical (D and E) effect on the width and the shift of the line shape.Applying the line deconvolution procedure, the basic plasma parameters i.e. electron temperature (T) and electron density (N) are recovered. The plasma parameters (T and N) are measured using independent diagnostics techniques as well. Good agreement is found among two sets of the N and T plasma parameters obtained from deconvolution procedure and independent diagnostics techniques.     

Stark broadening and shift of OII spectral lines in higher multiplets

Stark widths and shifts of nineteen singly-ionized oxygen spectral lines, mostly of higher multiplets, have been measured in a pulsed linear arc plasma in an oxygen-nitrogen mixture at 8.1×10²² m^?3 electron density and 60000 K electron temperature. The measured widths and shifts values are compared, for eight multiplets, with existing theoretical results.     

Absolute line intensities determination in the nu7 band of C2H4

Absolute intensities have been measured for 26 lines of C2H4 in the nu7 fundamental transition, using a tunable diode-laser spectrometer. These lines with 3< or = J"< or = 21, 2< or = Ka< or = 4, 2< or = Kc< or = 20 are located in the spectral range 920-980 cm(-1). The intensities have been measured by using two methods: the equivalent width method (EWM) and the line profile fit method (FPM). For the last one, three models have been tested: Voigt, Rautian and Galatry profiles.     

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.     

The role of the He I and He II metastables in the population of the Sn II,Sn III and Sn IV ion levels

On the basis of the temporal evolutions of the singly, doubly and triply ionized tin (Sn II, Sn III and Sn IV, respectively) spectral line intensities, in the pulsed helium and nitrogen plasmas, the important role of the He I and He II metastables has been observed in the Sn II, Sn III and Sn IV ionization and population processes. According to these processes, one can expect realization of several laser levels in the Sn II (11.07, 11.20, 12.44 and 13.11 eV), Sn III (15.91, 17.82, 19.13 and 20.19 eV) and Sn IV (20.51 eV) spectra. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in helium with tin atoms, as impurities, evaporated from tin cylindrical plates located in the homogenous part of the discharge tube. This plasma source provides good conditions for a generation of the Sn III, Sn IV and Sn V ions at relatively low electron temperatures (below 18,000 K) providing low background radiation around the intense Sn IV and Sn III spectral lines in the helium plasma. The 222.613 ± 0.0005 nm Sn IV line, not observed up to now, has been identified. The marked, but not classified 243.688 nm Sn spectral line is sorted by ionization stages. The shapes of Sn III and Sn IV lines, ranged between 207 nm and 307 nm, have been obtained. At a 17,500 K electron temperature and 1.07 × 10²³ m^− 3 electron density the Stark broadening was found as the dominant mechanism in the mentioned lines broadening. The measured Stark widths of the prominent nine Sn IV and seven Sn III lines are the first data in the literature. The Stark widths of the intense 229.913 nm and 288.766 nm Sn IV lines can be used for the plasma electron density and temperature diagnostics purposes.     

Stark broadening and shift of multiply ionized carbon spectral lines

Stark widths and shifts of sixCII, threeCIII and twoCIV spectral lines have been measured in a linear pinch discharge plasma and compared with available experimental and theoretical data. Electron density, (0.86?1.64)×10²³ m^?3, was determined by single wavelength laser interferometry using the visible 632.8 nm transition of He-Ne laser. The electron temperature of 38000 K was derived from the Boltzmann slope of severalCII spectral lines, and ratios of severalCII toCIII spectral lines. The stark widths (w) dependence on:(i) the upper-level ionization potential (I) of corresponding lines;(ii) net charge (z) of the emitter core seen by the optical electron undergoing transition, and(iii) electron temperature (T) was found to be of the form:w=az ² T ^?1/2 I ^?b . However, it should be noticed that the essential role in the obtained trends belongs to the energy of the emitter core. The established overall trend is used to predict Stark widths of uninvestigated spectral lines originating from the given transition arrays.     

Observation of spectral line profiles emitted by an inductively coupled plasma—I.: On the wavelength shift of spectral lines

Profiles of 16 spectral lines stemming from 8 elements (Ar, Na, Cu, Sr, Cd, Ba, Mg and Li) emitted by an inductively coupled plasma (ICP) have been observed and measured with a pressure-scanning Fabry-Perot interferometer. In the process of profile observations, we have found wavelength shifts of spectral lines in an ICP and for the first time studied this phenomenon quantitatively and systematically in a spectrochemical source. The profiles of spectral lines emitted by the ICP have been compared with those emitted by hollow cathode lamps. The magnitude of the wavelength shift to the red or the blue varied more or less with the plasma conditions, observation position and the concentration of a concomitant, cesium. In the present work the observed line profiles were not deconvoluted for the apparatus profiles. Typically the order of magnitude of the wavelength shift measured for spectral lines that show large shifts at an observation height of about 4 mm in an “analytical” ICP is n × 10^?3 nm, where n is about 4 for Ar I 427.2 nm and about 1 for Cu I 521.8 nm and Sr II 430.5 nm. With regard to the wavelength shift, several trends and/or regularities were found. The Stark effect is considered as the main cause of the phenomena.     

On the use of the Hα spectral line to determine the electron density in a microwave (2.45 GHz) plasma torch at atmospheric pressure

The electron density of an argon microwave (2.45 GHz) plasma flame generated at atmospheric pressure has been determined by using the Stark broadening of the experimentally measured H_α line emitted by the discharge. The H_β line was not observable under the experimental conditions of this discharge. Two methods have been employed to obtain the electron density from the Stark broadening of the H_α line. The first used the Gigosos–Cardeñoso computational model that considers the strong broadening of the H_α line by ionic dynamics. Alternatively, a second method based on a calibration of Stark broadenings of H_α and H_β lines offered a simpler way to obtain the electron density.     

Spectroscopic diagnostics of laser-induced plasmas

An overview of spectroscopic diagnostics techniques for low temperature plasmas is presented with an emphasis to electron number density — N_e measurement. Stark broadening of non-hydrogenic atom and positive ion spectral lines is given. The attention is drawn to experimental techniques used for line intensity and line profile measurement. Self-absorption test, importance of Abel inversion, deconvolution of experimental line profiles and measurement of line asymmetry are treated in some detail in order to improve N_e measurements. Finally the sources of theoretical and experimental Stark broadening data are reviewed and some details discussed.     

The first measurement of the In III Stark widths

The shapes of 16 doubly ionized indium (In III) spectral lines have been measured in the laboratory helium plasma at 13,000 K electron temperature and 1.48 × 10²³ m^− 3 electron density. At mentioned plasma conditions the Stark broadening has been found as the dominant mechanism in the line shape formation. Here presented data are the first reported values for Stark widths (W) related to the specific In III lines. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in helium with indium atoms, as impurities, evaporated from indium cylindrical plates located in the homogenous part of the discharge, providing conditions free of self-absorption. At the above mentioned helium plasma conditions we have found symmetrical In III line profiles of the Voigt type. This means that the expected hyperfine structure splitting (Δ_hfs) in the investigated In III lines has been overpowered by Stark and Doppler broadening. We recommend the found W values of the intense and well isolated 298.280, 403.232 and 524.877 nm In III lines for the plasma electron density diagnostic ranged between 10²¹ m^− 3 and 10²³ m^− 3.