Temperature dependence of atomic spectral line widths in a plasma

We investigated here temperature dependence of Stark widths for neutral atom spectral lines in order to find a more precise method for scaling with temperature than sometimes used dependence T^-1/2, which is often inadequate particularly for Stark broadening of neutral emitter lines. We found here an analytical scaling with temperature within simplified semiclassical approaches of Freudenstein and Cooper and Dimitrijević and Konjević. For analysis of the temperature dependence, lines of HeI were used.     

Some regularities within the Stark widths and shifts of resonance ion lines from Li to Ca

A periodic dependence of the Stark widths and shifts of resonance lines, for singly- and doubly-ionized elements, has been found on nuclear charge number Z. These periodicities were found for Griem's theoretical values of the Stark parameters of resonance lines of some singly charged ions from Li to Ca; for other singly- and doubly- charged ions, this parameter was calculated from Griem's semiempirical formula. The dependence of the Stark parameters of the resonance lines on atomic polarizability X has been determined and used to estimate Stark widths and shifts for other singly-charged ions. These values are compared with estimates derived form Griem's semiempirical formula for the Gaunt factor g = 0.2.     

Use of the quadratic Stark effect to determine the concentration of charged particles in a plasma from the broadening of lithium and sodium lines

The Stark constants for the quadratic Stark effect have been calculated for a number of spectral lines of sodium and lithium atoms. To evaluate the contours of the spectral lines, the nonstationary collision theory has been used for electron broadening, and Holtsmark's theory for ionic interactions. Satisfactory agreement with experimental data has been obtained. The concentration of the charged particles has been measured in a dc arc.     

Stark Broadening Regularities within Successive Ionization Stages in Krypton and Xenon

On the basis of existing experimental and theoretical results on Stark widths of neutral and multiply ionized states of krypton and xenon, we have indicated existence of certain regularities of Stark broadening for ns-np types of transitions. These regularities were used to estimate the Stark widths of spectral lines from KrIV and XeI spectra that have not yet been measured or calculated.     

Measurement of the Stark Broadening of Atomic Emission Lines in Non–Optically Thin Plasmas by Laser‐Induced Breakdown Spectroscopy

We propose a new method for determining the Stark broadening of atomic emission lines using laser‐induced breakdown spectroscopy. The method allows the determination of the Stark broadening in non–optically thin plasmas, through the introduction of a correction for self‐absorption. Couples of lines of the same species are considered. If one of the Stark broadenings is known, the determination of the other does not require the measurement of the electron density of the plasma. Examples are given for the application of the proposed method to the measurement of the Stark broadening of several aluminum emission lines (Al I at 308.2 nm, Al I at 394.4 nm, and Al I at 396.2 nm).     

激光诱导Ni等离子体发射光谱的空间演化特性研究

在350～600 nm波长范围内测定了激光烧蚀Ni等离子体中Ni原子的空间分辨发射光谱.测定了385.83 nm发射光谱线的相对强度和STARK展宽及其随径向的变化特性.结果表明,在沿激光束方向上,当距离靶表面0～2.5 mm范围内变化时,谱线的STARK展宽和谱线的强度都随距靶面距离的增大先增大,但增大到最大值后随距离的进一步增大而减小.谱线强度和STARK加宽的最大值都出现在离靶面约1.5 mm处.     

激光诱导Ni等离子体发射光谱的空间演化特性研究

在350- 600nm 波长范围内测定了激光烧蚀Ni等离子体中Ni原子的空间分辨发射光谱.测定了385.83 nm发射光谱线的相对强度和STARK展宽及其随径向的变化特性。结果表明, 在沿激光束方向上, 当距离靶表面0-2.5mm范围内变化时,谱线的STARK展宽和谱线的强度都随距靶面距离的增大先增大,但增大到最大值后随距离的进一步增大而减小。谱线强度和STARK加宽的最大值都出现在离靶面约1.5mm处。     

GdOBr:Eu荧光谱的高压研究

本文在室温下测量了GdOBr:Eu的常压和高压荧光谱,光谱范围在13000～21500cm-1之间,压力至12GPa.常压下,清晰可辨的荧光谱线共有43条,这些谱线由Eu3+4f6组态内5D0-2至7F0-5的跃迁产生。由荧光谱线得到26个晶场能级(Stark能级).谱线绝大部分随压力红移,少数几条谱线随压力先蓝移后红移。所有谱线的强度随压力升高而减弱。7F0-5的能级随压力的变化规律比较复杂,而5D0-5各能级均随压力的升高几乎线性地降低。     

Determining the charged particle concentration in a dc arc from the emission spectrum of sodium

Several methods of measuring charged particle concentrations from the emission spectrum of sodium are discussed. The limits of applicability of each method are specified. Discrepancies in charged particle concentrations measured on the basis of the broadening of spectral lines with different Stark constants in an arc discharge are due to the fact that the peak intensities of these lines are determined in various narrow discharge zones. A method for determining the charged particle concentration over the radius of an inhomogeneous axisymmetrical source (arc discharge) from the broadening of several emission lines of sodium with different Stark constants is proposed. It is shown that in the case of strongly inhomogeneous sources the vanishing of spectral lines from the series cannot be used to determine the charged particle concentration in the plasma.In conclusion, the authors wish to thank M. A. El'yashevich for discussing the present paper.     

光泵分子气体远红外光谱的AC Stark效应

本文应用图论法研究光泵激光气体分子的波谱特性。假定了:1.分子与外来信号场相互作用输运过程中只涉及到六个能级;2.泵场强远大于探测场强。在这些假定下求解密度矩阵方程,获得一套反映受激分子波谱特性的解析表达式。应用这些表达式,可求得不同频率的泵场作用下分子气体的远红外波谱特性。本文特别叙述分子振动基态远红外光谱的AC aStark效应。结果表明:在谐振点AC aStark分裂的值与C.H.Townes所得结果基本相同,在受激发射和吸收共存的情况下,特性曲线的总趋向与他的结果基本一致。调谐曲线有些部份反映发射特性,有些部份反映吸收特性,在发射和吸收的过渡部份,吸收和发射都很小,而且具有特殊的过渡特性。     

Line broadening studies in low energy plasma focus

Optical emission spectroscopic studies were carried out to characterise the plasma leading to the estimation of two plasma parameters, electron density and temperature. These experiments were conducted on a 2 kJ plasma device which is equipped with squirrel cage electrode configuration enclosed in a glass vacuum chamber filled with hydrogen at a pressure of 5 mbar. Spectral emissions obtained from each flash were photographed in the region of 4000–6000 Å using one metre Czerny-Turner spectrograph cum monochromator. Detailed examination of the observed features showed that theH _β andH _λ lines of hydrogen showed significant broadening of the order of 35 Å FWHM which is due to Stark effect expected in high density plasmas. Further several atomic lines of Cu and Zn from the electrode material (brass) showed broadening which was due to quadratic Stark effect. A comparative study of the broadening of lines obtained in DC arc, hollow cathode and plasma focus was made. Electron density from Stark broadened hydrogen lines and quadratic Stark Coefficient C₄ for the CuI and ZnI lines were evaluated. The excitation temperature was determined from the line intensity ratio method using CuI lines.     

New method for polarization measurements of magnetic fields indense plasmas

Measurements of magnetic fields based on observations of the Zeeman splitting ω_B of spectral lines is a virtually impossible task in dense plasmas of powerful Z-pinches where the Stark splitting in the ion microfields ω_F is much greater than ω_B. In this situation, much better diagnostics of magnetic fields can be achieved through polarization difference contours obtained by subtracting profiles of the same spectral line observed in two orthogonal linear polarizations. In this way the obscuring role of the Stark effect is significantly diminished. In the present paper it is shown that the most sensitive and accurate measurements of the magnitude and the direction of the magnetic field in a dense plasma can be conducted employing central Stark components of hydrogen or hydrogen-like spectral lines. The polarization contour of a central Stark component turned out to be much more sensitive to the magnetic field than the polarization contour of a lateral component of the same line, namely by a factor of (ω_F/ω_B) ³≫1. This constitutes a drastic enhancement of the previously suggested method that had used the polarization contour of a lateral Stark component because in dense plasmas a typical value of the above factor is (ω_F/ω_B)³⩾10³ . The new method can also be used for laser fusion plasmas and for some astrophysical objects such as magnetic white dwarfs     

FIR Stark spectroscopy on optically pumped CH3OH laser

An extensive theoretical and experimental analysis of the absorption and emission spectrum of a CH₃OH FIR-laser excited by a conventional CO₂ laser is presented. Particular interest is devoted to the Stark shifts of the pump and lasing lines and to the electric field dependence of the Fir-laser output of the various lines. The offsets with respect to the exciting radiation and the Stark shifts of the IR absorption (pump) lines are measured by means of the transferred Lamb dip technique. The theoretical behaviours of the Stark patterns are calculated for several choices of the quantum numbers and selection rules involved in the transitions. A large variety of experimental results are reported and compared to theory. Non-linear Stark shifts have been observed for the 37.5m FIR laser line and for the IR-pump transitions excited by the 9-P(38) and 10-R(38) CO₂ laser Lines. Line assignments are proposed and new FIR laser lines are reported.     

Energy level offset analysis of lead atom in laser plasma

The optical emission spectra of the plasma generated by a 1064 nm laser irradiation of lead target in air were recorded and analyzed. Temporal evolvement trait of spectral lines was investigated. The Stark width and line shift were measured at different delay time and laser energies. The electron densities were determined using Stark-broadening parameters of spectral lines. The atomic energy level offset in plasma surroundings was explored by analyzing the line shift. The experimental data of Stark widths and line shifts were analyzed using the regularity of the Stark parameters’ dependence on effective ionization potential. However an inverse experimental result was found compared with the theoretical calculation. In addition, the change of the Stark widths and line shifts with the delay time and laser energies was discussed.     

On the Stark Broadening Regularities Along a Homologous Sequence of the IV B Subgroup in the Periodic System

On the basis of the exiting experimental results of the Stark widths we have demonstrated the existence of a Stark-width dependence on the upper-level ionization potential for the homologous sequence of the fourth B group of the elements in the periodic system for three types of transitions in the case of singly-ionized atoms. On the basis of these regularities we have predicted Stark widths of some Ge II and Pb II spectral lines. Stark widths predicted for Ge II, Sn II i Pb II spectral lines were compared with our calculated values on the basis of the semiempirical and modified semiempirical formula.     

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.     

Balmer-alpha and Balmer-beta Stark line intensity profiles for high-power hydrogen inductively coupled plasmas

We compare Balmer-alpha(Hα) and Balmer-beta(Hβ) emissions from high-power(1.0–6.0 kW) hydrogen inductively coupled plasmas(ICPs), and propose region I(0.0–2.0 kW), region II(2.0–5.0 kW), and region III(5.0–6.0 kW). In region I, both Hαemission intensity(Iα) and Hβemission intensity(Iβ) increase with radio frequency(RF) power, which is explained by the corona model and Boltzmann’s law, etc. However, in region II, Iαalmost remains constant while Iβrapidly achieves its maximum value. In region III, Iαslightly increases with RF power, while Iβdecreases with RF power,which deviates significantly from the theoretical explanation for the Hαand Hβemissions in region I. It is suggested that two strong electric fields are generated in high-power(2.0–6.0 kW) hydrogen ICPs: one is due to the external electric field of high-power RF discharge, and the other one is due to the micro electric field of the ions and electrons around the exited state hydrogen atoms in ICPs. Therefore, the strong Stark effect can play an important role in explaining the experimental results.     

Stark broadening of neutral helium lines

Using a semiclassical approach for the Stark broadening of atomic lines, we have calculated electron and proton impact line widths and shifts of 56 neutral He lines in the ultraviolet, visible and i.r. region of the spectrum. The comprehensive set of results obtained is used for investigation of Stark-broadening parameter regularities within the spectral series.     

On the Stark broadening of Sr+ and Ba+ resonance lines in ultracold neutral plasmas

We report results of the Stark broadening calculations for Sr⁺ and Ba⁺ resonance lines in ultracold plasmas using semiempirical formulas and numerical computer simulation technique. The simulation results show that strong collisions dominate Stark broadening at very low electron temperatures and weak collision approximation used recently by Vrinceanu et al. cannot be applied in this temperature region. Consequently, the temperature trend of Stark widths and shifts changes from successfully used at elevated temperatures to an increasing trend with temperature, which is characteristic for strong collisions at low temperature.     

The Stark effect on optically pumped CH3OD and CD3OH lasers

Laser action and the Stark effect in optically pumped CH₃OD and CD₃OH have been investigated using a rectangular metal-dielectric hybrid waveguide. In experiments without an electric field, 33 CW Submillimeter laser lines have been observed, including nine new lines. The Stark effect has been investigated for all of these lines and it has been found that only two of them split. Paschen curves for these lasing materials have also been measured.