Relative Intensities Of Spectral Lines Research Articles

Analysis of constituents present in smokeless tobacco (Nicotiana tabacum) using spectroscopic techniques

Laser-Induced Breakdown Spectroscopy (LIBS) is an analytical technique used to identify and quantify the elements present in any type of material present in any phase (solid, liquid, gas, and aerosol). In the present work, our objective is to find the presence of toxic and other elements in chewing tobacco ( Nicotiana tabacum ) using LIBS. Spectral signatures of elements like C, Fe, Si, Mg, Mn, Ca, Ti, Na, H, N, K, O, along with some toxic elements Al, Sr, Li, Cu, Sb, and Cr are observed in the LIBS spectra of these tobacco samples. The spectral intensity ratio is measured for quantitative analysis of elements present in the samples. Further, Atomic Absorption Spectroscopy is used for determining absolute concentration in these samples. A relation between the AAS result and the relative intensity of spectral lines measured in the LIBS is obtained using regression analysis. The multivariate technique, Principal Component Analysis (PCA), discriminates all the samples based on their toxicity and other constituents. Molecular study (Photoacoustic spectroscopy (PAS), UV-Visible (UV–vis), and FT-IR) of tobacco samples were performed to analyze the molecules present in the tobacco samples.

Investigation and diagnostics of plasma flows in a pulsed plasma accelerator for experimental modelling of processes in tokamaks

This paper presents the experimental results on electron, ion temperatures and densities in a pulsed plasma accelerator. The values of electron densities and temperatures were computed using the methods of relative intensities of Hα and Hβ lines, Hβ Stark broadening, and the technique is based on Faraday cup beam current measurements. In this work, a linear optical spectrometer S-100 was used to acquire the emission spectra of hydrogen and air plasmas. In this spectrum, there are some lines due to Fe, Cu, N2, O2, and H2. The series of visible lines in the hydrogen atom spectrum are named the Balmer series. The spectral emissions of iron and copper occur throughout the gas breakdown and ignition of an arc discharge, during the erosion and sputtering of materials. The vacuum chamber and coaxial electrodes were made. The electron temperatures and densities in a pulsed plasma accelerator, measured via relative intensities of spectral lines and Stark broadening, at a charging voltage of a capacitor bank of 3 kV and a working gas pressure in a vacuum chamber of 40 mTorr, were 2.6 eV and 1.66 · 1016 cm−3 for hydrogen plasma. These results were compared with the Faraday cup beam current measurements. However, no match was found. Considering and analyzing this distinction, we concluded that the spectral method of plasma diagnostics provides more accurate results than electrical measurement. The theory of probe measurements can give approximate results in a moving plasma.

Measurement of electronic temperature of laser-induced plasma channels at various pressures in argon by relative intensities of spectral lines

In this paper, we study the properties of laser-induced plasma channels formed by femtosecond laser radiation in argon. The electron temperature of the plasma channels is calculated by the method of relative intensities of spectral lines.

The temperature characteristics of plasma induced by femtosecond laser radiation

In this work, the plasma temperature in an argon and nitrogen medium is measured at various pressure values. Such data can be used to calculate plasma parameters: electron concentration, collision frequency with atoms and molecules, etc. Two approaches are used to measure temperature: using a pyrometer and measuring the relative intensity of spectral lines.

Experimental Investigation on the Electron Temperature of Laser-Induced Mg Plasmas

A series of plasma characteristic spectral lines of Mg alloy were obtained under nanosecond laser shock produced by a pulsed Nd : YAG laser (1 064 nm, maximum energy 500 mJ), which was taken under standard atmospheric pressure and at room temperature. Results indicated that the evolutionary rates of spectral lines were different, and the laser energy was enough to ionization Mg alloy under this experimental condition by the spectral lines of MgⅠ, MgⅡ. The electron temperature of Mg plasma were calculated by the measured relative Emission-line intensity(MgⅠ383.2 nm, MgⅠ470.3 nm, MgⅠ518.4 nm). The experimental results showed that the secondary excitation Mg atoms could be got under this experimental condition. The electron temperature of Mg plasma decreased with the laser energy reduced while the laser energy was in the range of 200～500 mJ. When the laser energy was in the range of 350～500 mJ, the electron temperature changed rapidly. When the laser energy was in the range of 200～350 mJ, the electron temperature changed slowly and tended towards stability. It is found that when the laser energy was 300 mJ, the plasma temperature raised suddenly, which could not accord with the trend because of plasma shielding. When the laser energy was 300 mJ, the relative intensity of spectral lines was reduced which was lower than that of 350 and 250 mJ. And it is against the variation trend of the relative intensity of spectral lines increases with the increase of laser energy, which prove plasma shielding phenomenon had occurred and plasma with high power laser separate the coupling between laser and material. The plasma temperature was increased significantly, which is not consistent with the trend .When the plasma shielding phenomenon happened, laser energy was absorbed by the plasma, resulting in the rise of plasma temperature.

Parameters of supersonic astrophysically-relevant plasma jets collimating via poloidal magnetic field measured by x-ray spectroscopy method

Application of external magnetic field to a laser-generated plasma flows allows to investigate stable, large aspect ratio plasma jets which are relevant to a number of astrophysical cases. In the experiment with 0.6 ns, 40 J laser pulses focused to 700 μm focal spot at solid CF2 target in presence of 20 T poloidal magnetic field the parameters of the plasma jet were studied by means of spatially resolved x-ray spectroscopy. Focusing spectrometer with spatial resolution was used to record the temporally-integrated x-ray emission spectra of the plasma with spatial resolution along the jet propagation. Using the relative intensities of spectral lines emitted by F He-like ions, the electron temperature Te and density Ne profiles of the plasma are obtained. It is shown that Ne decreases monotonically in the case without B-field, but demonstrates an extended density profile up to 10 mm when 20 T magnetic field is applied. Ne values are consistent with that observed via interferometry diagnostics, thus providing the confidence in our x-ray spectroscopy analysis techniques.

The influence of dust particles on the intensities of plasma emission lines

Emission spectra of glow-discharge plasma in Ar–He gas mixture have been measured. It is established that the introduction of Al2O3 dust particles into plasma significantly changes the relative intensities of spectral lines.

Spectroscopic determination of the relative concentrations of H2, HD, and D2 molecules in nonequilibrium hydrogen-deuterium plasma: I. Kinetic models

The possibility of estimating the relative concentrations of H2, HD, and D2 molecules in nonequilibrium low-pressure hydrogen-deuterium plasma from the observed relative intensities of spectral lines of atoms and molecules is examined. It is demonstrated that the intensity ratios of the Balmer lines of hydrogen and deuterium atoms can be used to estimate the relative concentrations of the isotopic molecules in two limiting cases, namely, a fairly high degree of dissociation of the molecules in plasma (model 1a) and a fairly low one (model 1b). A procedure is suggested for deriving the relative concentrations of H2, HD, and D2 molecules from the observed intensity ratios of Q-branch lines of Fulcher-α bands of these molecules within a simplified model of the excitation and deactivation of rovibronic levels (model 2). The procedures proposed here are fully independent, for they are based on consideration of different physical processes, use different experimental data, and do not involve any fitted parameters. Therefore, simultaneous use of the different independent models provides means to assess their applicability under particular experimental conditions.

Improved and expanded measurements of transition probabilities in UV Ar ii spectral lines

Transition probabilities have a significant interest in the astrophysical field. The aim of this experiment is to extend the present data base of measured Ar II transition probabilities to the ultraviolet (UV) region and to improve the quality of some of the already existing data. Despite all the efforts made to assemble an accurate set of transition probabilities (Aki), some of the data recommended by the National Institute of Standards and Technology (NIST) for Ar II spectral lines in the UV region have uncertainties around 50percent. We measured relative intensities of spectral lines emitted from a low-pressure-pulsed discharge lamp which generates an argon plasma. Excitation temperatures of 19 000–22 000 K are determined from the Boltzmann-plot of 11 Ar II spectral lines for which accurate Aki data are available from the literature. The transition probabilities of these 11 spectral lines were used for calculating new Aki-values. Electron densities (Ne) of 3.5–9.0 × 10 22 m −3 are determined by two-wavelength interferometry method. The measurements yield to a collection of 43 atomic transition probabilities of Ar II lines in the spectral region of 294–386 nm, 11 of which are new, at least up to the authors knowledge, and 22 improved Aki-values for which the existing data in the literaturehaveuncertaintiesaround50percent.Comparisonwithprevious datashowshowour measurements have good agreement with the most accurate Aki-values from the bibliography, whereas some of the values recommended by NIST present a significant disagreement.

Optical emission spectroscopy of Aluminum Nitride thin films deposited by Pulsed Laser Deposition

In this work we study the Aluminium Nitride plasma produced by Nd:YAG pulsed laser, (λ = 1064 nm, 500 mJ, τ = 9 ns) with repletion rate of 10 Hz. The laser interaction on Al target (99.99%) under nitrogen gas atmosphere generate a plasma which is produced at room temperature; with variation in the pressure work from 0.53 Pa to 0.66 Pa matching with a applied laser fluence of 7 J/cm2.The films thickness measured by profilometer was 150 nm. The plasma generated was at different pressures was characterized by Optical Emission Spectroscopy (EOS). From emission spectra obtained ionic and atomic species were observed. The plume electronic temperature has been determined by assuming a local thermodynamic equilibrium of the emitting species. Finally the electronic temperature was calculated with Boltzmann plot from relative intensities of spectral lines.

On the reliability of probe diagnostics in RF plasma

The errors of probe diagnostics of the resting or slow-moving plasma of Q-machines or dc discharges are shown to lie typically within a range of ±(20–30)%. Problems of probe diagnostics of RF plasma and modern approaches to their solving are considered. The objectivity of probe diagnostics of RF plasma is established by the mutual agreement between the electron energy distribution functions measured in the same experiment using the Langmuir probes and the method of relative intensities of spectral lines.

Excitation wavelength dependence of water-window line emissions from boron-nitride laser-produced plasmas

We investigated the effects of laser excitation wavelength on water-window emission lines of laser-produced boron-nitride plasmas. Plasmas are produced by focusing 1064 nm and harmonically generated 532 and 266 nm radiation from a Nd:YAG laser on BN target in vacuum. Soft x-ray emission lines in the water-window region are recorded using a grazing-incidence spectrograph. Filtered photodiodes are used to obtain complementary data for water-window emission intensity and angular dependence. Spectral emission intensity changes in nitrogen Ly-α and He-α are used to show how laser wavelength affects emission. Our results show that the relative intensity of spectral lines is laser wavelength dependent, with the ratio of Ly-α to He-α emission intensity decreasing as laser wavelength is shortened. Filtered photodiode measurements of angular dependence showed that 266 and 532 nm laser wavelengths produce uniform emission.

Diagnostics of plasma produced by femtosecond laser pulse impact upon a target with an internal nanostructure

X-ray diagnostics of the interaction of femtosecond laser pulses with intensities of 1016–1018 W/cm2 with CO2 clusters and frozen nanosize water particles is carried out. The stage of cluster expansion and the formation of a plasma channel, which governs the parameters of the formed X-ray radiation source and accelerated ion flows, is studied. The measurements are based on recording spatially resolved X-ray spectra of H- and He-like oxygen ions. Utilization of Rydberg transitions for spectra diagnostics makes it possible to determine plasma parameters on a time scale of t ∼ 10 ps after the beginning of a femtosecond pulse. The role of the rear edge of the laser pulse in sustaining the plasma temperature at a level of ∼100 eV in the stage of a nonadiabatic cluster expansion is shown. The analysis of the profiles and relative intensities of spectral lines allows one to determine the temperature and density of plasma electrons and distinguish the populations of “thermal” ions and ions that are accelerated up to energies of a few tens of kiloelectronvolts. It is shown that the use of solid clusters made of frozen nanoscale water droplets as targets leads to a substantial increase in the number of fast He-like ions. In this case, however, the efficiency of acceleration of H-like ions does not increase, because the time of their ionization in plasma exceeds the time of cluster expansion.

Optical Emission Spectroscopy Measurements and Simulation of Radioelement Volatility During Radioactive Waste Treatment by Plasma

An optical emission spectroscopy (OES) method has been used to measure the concentration above the melt of some radioelements, 137Cs, 60Co and 106Ru during the vitrification of radioactive wastes by thermal plasma. This method allows the study of non homogeneous optically thin plasmas exhibiting a symmetry plane without sophisticated tomographic systems. Local plasma temperatures above the melt have been evaluated using measured relative intensities of spectral lines of the plasma-forming gas. Radioelement concentrations in the plasma are deduced from the intensity ratio of the radioelement–gas spectral lines. A computer model is used to simulate the volatility of 137Cs, 60Co and 106Ru, during the treatment of radioactive wastes by thermal plasma. This model is based on the calculation of system composition using the free enthalpy minimization method, coupled with the equation of mass transfer at the reactional interface. In this study, the OES measurements and the computer model allowed the determination of this radioelement volatility depending on the parameters like plasma current, and the nature of atmosphere furnace. The results of the model are compared to those obtained by OES measurements.

Solar plasma temperature diagnostics in flares and active regions from spectral lines in the range 280–330 Å in the SPIRIT/CORONAS-F experiment

Plasma temperature diagnostics in solar flares and active regions has been carried out using data from the SPIRIT spectroheliograph onboard the CORONAS-F satellite. The temperature distribution of the differential emission measure (DEM) has been determined from the relative intensities of spectral lines recorded in the spectral range 280–330 A in the period from 2001 to 2005. Analysis of these distributions has led to the conclusion about the existence of active regions with various “characteristic” temperature compositions. The presence of a hot plasma with temperatures logT = 6.8−7.2 in active regions has been established for the first time from XUV spectroscopic data and monochromatic X-ray line images. The DEM distribution for intense long-decay flares has also been obtained for the first time and a similarity of the temperature compositions for flares of different classes at the decay phase has been found. The spectra have been modeled on the basis of the calculated DEMs. The systematic discrepancies between the calculated and measured line intensities are discussed.

X-ray fluorescent analysis of alloys by total relative intensities of spectral lines of components

The questions of increasing the accuracy of results of x-ray fluorescent analysis are considered. The experimental data that confirm the efficiency of processing the spectra by total relative intensities of spectral lines in the samples are presented.

Characterization of the pulse plasma source

Characterization of the pulse plasma source through the determination of the local thermodynamic equilibrium (LTE) threshold is described. The maximum electron density measured at the peak in discharge current is determined by the width of the He II Paschen alpha spectral line, and the electron temperature is determined from the ratios of the relative intensities of spectral lines emitted from successive ionized stages of atoms. The electron density and temperature maximum values are measured to be 1.3 × 1017 cm−3 and 19 000 K, respectively. These are typical characteristics for low-pressure, pulsed plasma sources for input energy of 15.8 J at 130 Pa pressure in helium–argon mixture.The use of LTE-based analysis of the emission spectra is justified by measurement of the local plasma electron density at four positions in the discharge tube using a floating hairpin resonance probe. The hairpin resonance probe data are collected during the creation and decay phases of the pulse. From the spatio-temporal profile of the plasma density a 60 µs time-window during which LTE exists throughout the entire plasma source is determined.

Local field effects and stimulated multimode scattering of resonance radiation in a two-level medium

Scattering of resonance radiation in a dense two-level medium is considered with allowance for the local field effects. The system is studied in the framework of the mean-field approximation for a modified hierarchy of the Bogoliubov-Born-Green-Kirkwood-Yvon equations for reduced density matrices of an ensemble of atoms and modes of a quantized electromagnetic field. The local field correction is consistently derived from the initial Hamiltonian of the system. The problem of scattering of a short rectangular pulse from a quasi-point sample is considered numerically and theoretically. The possibility of a multimode spectrum of scattered radiation with frequencies multiple of the Rabi frequency and with other intermediate frequencies is demonstrated. The relative intensities of spectral lines are determined.

Atomic data and spectral line intensities for Mg V

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Mg V. The configurations used are 2s 22p 4, 2s2p 5, 2p 6, 2s 22p 33s, 2s 22p 33p, and 2s 22p 33d, giving rise to 86 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies, 10, 20, 30, 40, and 50 Ry, in the distorted wave approximation. Excitation rate coefficients (not tabulated here) are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. To calculate excitation rate coefficients, collision strengths at low and high energy limits are calculated by a method described by Burgess and Tully. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10 8–10 14 cm −3 at an electron temperature of log T e = 5.4, corresponding to the maximum abundance of Mg V. Fractional level populations and relative spectral line intensities are also calculated. Our calculated intensities are compared with the active region observations from the solar EUV rocket telescope and spectrograph (SERTS) and the diagnostic properties of Mg V are discussed. This dataset will be made available in the next version of the CHIANTI database.

Atomic data and spectral line intensities for Ne III

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ne III. The configurations used are 2s 22p 4, 2s2p 5, 2p 6, 2s 22p 33s, 2s 22p 33p, and 2s 22p 33d giving rise to 86 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies, 5.2, 10, 15, 20, and 25 Ry. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10 8 to 10 14 cm −3 at an electron temperature of log T e (K) = 5.0, corresponding to maximum abundance of Ne III. Relative spectral line intensities are calculated.