An apparatus for measuring Thomson scattering from an inductively coupled plasma

An experimental arrangement is presented which has been proven capable of measuring Thomson scattering from an inductively coupled plasma (ICP). This system has been shown to reject stray light to a sufficient extent that useful scattering signals can be measured as near as 0.3 nm from the incident laser wavelength. In this paper, design considerations are discussed and a viable experimental system is described. Preliminary Thomson scattering results are presented.     

On the significance of radiation trapping in the inductively coupled plasma

On the basis of an intuitive argument and experimental evidence, the authors suggest that the populations of radiating states (³P₁,¹p_t) and metastable states (³P₂,³P₀) of atomic argon are collisionally equilibrated in the ICP discharge. A mechanism for allowing suprathermal populations to exist in the analytical region of the ICP is proposed based on the “trappin” of resonance radiation within the discharge boundaries. The possible consequences of this model are discussed.     

Spectrochemical analysis of mediaeval glasses by means of inductively coupled plasma and glow discharge sources

For the analysis of mediaeval glass fragments, the inductively coupled plasma (ICP) and the Grimm glow discharge source (GDS) were used.For ICP measurement, the glass samples were digested with a mixture of sulphuric, nitric and hydrofluoric acids. For GDS investigations the glass powder, mixed with Cu or Zn powder was pressed to pellets. The sputtering rate was investigated in the case of standard and glass samples. Analytical curves were found to be linear over a wide concentration range for the investigated elements Fe, Mn, Al, Zn, Cr, Ni, Cu, Sn, Ti, V, Pb and Ag. The limits of detection and relative standard deviations met the requirements for archaeological glass analysis.     

A spectrometric study of a 40 MHz inductively coupled plasma—VII: Continuum of a binary mixture in the visible region of the spectrum

The continuum of an argon-hydrogen plasma is determined both theoretically and experimentally using the determination of physical parameters of the ICP. Similarly to pure argon plasma, radiative recombination is the main process in the continuum formation, below 500 nm. The presence of hydrogen results in an increase of the excitation temperatures and the electron number density, linked with an enhancement of the continuum. On the other hand, easily ionizable elements such as Na and K have no influence on these parameters. The injection of hydrogen via water is the main cause of variation of the ICP physical parameters.     

Appreciation of a collisional-radiative model for the description of an inductively coupled argon plasma

The collisional-radiative model has been applied to the argon ICP discharge in order to elucidate the excitation mechanism in the plasma. The population density distributions of 25 argon energy levels were calculated under a steady-state approximation by using the literature values of electron number density, 5 × 10 ¹⁴cm^?3 and electron temperature, 9000 K. In the case of an optically thin plasma, in which the induced absorption can be neglected, the calculated population densities showed an overpopulation for low lying states, and were very close to LTE values for the upper levels. These results suggest the following excitation mechanisms in the argon ICP; corona model for lower levels and ladder-like excitation and ionization by electron impact for upper levels. According to the present calculation, the non-overpopulation of argon metastable can be interpreted by the interconversion between metastable and radiative states. It has been found that the induced absorption of resonance lines in an optically thick plasma and the motion of species in an inhomogeneous plasma have significant effects on the population densities. The non-linear processes by collision between heavy particles were not predominant compared to electron impact processes.     

Some observations on electrothermal vaporisation for sample introduction into the inductively coupled plasma

The development and analytical utility of electrothermal vaporisation techniques employing a graphite rod for sample introduction into the inductively coupled plasma (ICP) are assessed. In most instances detection limits are superior to those obtained with nebulisation based systems, and are comparable to those obtained with graphite furnace atomic absorption spectrometry. A model is derived for the sample injection process. Additionally the major interference and alteration of the plasma excitation phenomena ensuing from the sample introduction of a solvent free aerosol are discussed in order to assess the analytical potential of the technique for routine μl volume sample introduction in ICP spectrometry. The capability for simultaneous multi-element analyses is maintained with the electrothermal vaporisation technique.     

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.     

Noise power spectra of the inductively coupled plasma

Noise power spectra for the ICP were determined under various conditions, by Fast Fourier Transform (FFT) digital techniques. The major noise types observed were white noise, low frequency noise, and high frequency proportional noise. The high frequency proportional noise increased with concentration of analyte and radio frequency input power. The high frequency proportional noise decreased with increasing nebulizer flow rate and coolant gas flow rate.. The low frequency noise components extended to higher frequencies as the resonance wavelengths of the measured transitions increased. Changing the observation height in the plasma determined which noise types were present in the noise power spectrum. At observation heights near the power coils, all three noise types were present, whereas, low frequency noise predominated at significantly greater heights. Changing the torch design changed the relative amplitudes of the different high frequency proportional noise components, but did not greatly change their respective peak frequencies.     

Atomic absorption spectrometric determination of Cd,Pb, Zn,Cu, Co and Fe in oyster tissue by direct atomization from the solid state using the graphite furnace platform technique

This paper describes a simple and rapid method for direct determination of traces of Cu, Zn, Pb, Co, Fe and Cd in the NBS oyster tissue, SRM No. 1566, by graphite furnace atomic absorption spectrometry. The solid sampling technique has been used and this results in much higher relative sensitivity by avoiding large dilution factors involved in the sample dissolution technique. The solid sampling technique also greatly reduces or eliminates serious risk of introducing contamination and/or loss of analytes involved in sample dissolution. The organic matrix of the oyster tissue is burnt off and removed by using a well-defined selective volatilization technique. Loss of Cd during charring (pyrolysis) stage is prevented by forming a relatively thermally stable compound of cadmium by adding (NH₄₂SO₄ solution to the oyster tissue sample. Also, quantitative data are presented on the effectiveness of the platform technique in removing matrix interferences. The platform technique uses an anisotropic pyrolytic graphite platform which is inserted into a commercial graphite tube.     

Direct determination of traces of copper,zinc, lead,cobalt, iron and cadmium in bovine liver by graphite furnace atomic absorption spectrometry using the solid sampling and the platform techniques

A simple and rapid method is described for direct determination of traces of Cu, Zn, Pb, Co, Fe and Cd in NBS bovine liver, SRM 1577, by graphite furnace atomic absorption spectrometry. The solid sampling technique was used, thereby avoiding the dilution factor involved in the solution technique, and also the risk of contamination from the environment in sample handling and from reagents, solvents and vessels. The organic matrix was burnt off and removed by using a well-defined selective volatilization technique combined with the analyte modification technique. Also, the effect of the platform technique in removing matrix interferences was studied using an anisotropic pyrolytic graphite platform inside the commercial graphite tube. The results of the “with platform” and the “without platform” techniques were equally accurate, but the “with platform” technique gave better precision.     

ESR and electronic absorption spectra of chromium acetylacetonato nitrosyl complexes

The cis- and trans-chromium nitrosyl complexes with formulae [Cr(NO)(acac)₂L] (L = H₂O, NH₃, pyridine and imidazole) and [Cr(NO)(ac     

Optical absorption spectra of praseodymium acetate complexes in solution

Results of analyses of the solution spectra of Pr³⁺ in the acetates of praseodymium, magnesium, calcium and cadmium complexes are presented. Slater-Condon (F₂, F₄ and F₆), configurational interaction (α,β), spin-orbit (ξ_4f), nephelauxetic ($\text{β}$) bonding (δ) and Judd-Ofelt (T₂T₄ and T₆) intensity parameters are evaluated. Judd-Ofel intensity relationship has been used in the calculation of electric dipole line-strengths. Theoretical evaluation of predicted radiative lifetimes (τ_R) of the electronic excited states ³P₁, ³P₀ and ¹D₂ of Pr³⁺ in four diff been carried out.     

A new microwave plasma at atmospheric pressure

Plasma at atmospheric pressure can be obtained by surface wave propagation with a surfatron. If the plasma is produced within a quartz tube, it is constricted to a diameter of approx. 1 or 2 mm but its length can attain some tens of centimeters with microwave power as low as 100 W. This plasma is quite uniform along the axis, with a typical electron density of 3 × 10¹⁴ electrons/cm³. Since the excitation and gas temperatures are lower than 4000 K, the plasma is far from local thermodynamic equilibrium. High stability and repeatability is achieved with an argon flow of 0.2–17 l/min. Applications are foreseen in the field of optical spectroscopy and plasma chemistry.     

Evaluation of an inductively-coupled plasma with an extended-sleeve torch as an atomization cell for laser-excited fluorescence spectrometry

An inductively-coupled plasma (ICP) with an extended-sleeve torch has been evaluated as an atomization cell for laser-excited fluorescence spectrometry. Limits of detection for 20 lines are given. The detection power is almost equivalent to that obtained by excitation with a hollow-cathode lamp. Interelement effects and spectral interferences are discussed.     

Determination of nanogram quantities of cobalt in complex matrices by flameless atomic absorption spectrometry

The application of flameless atomic absorption spectrometry to determination of a little as 10 pg of Co is described. Cobalt is extracted into ethyl acetate as the pyrrolidinedithiocarbamate complex. This system is effective in removing matrix effects due to high concentrations of various complexing agents, strong oxidants, and reductants that are present in the original samples.     

Electron spin resonance and optical absorption studies of copper-oxime chelates in dimethyl formamide and pyridine

ESR and optical absorption studies on Cu(II) chelates of 2-hydroxyacetophenone-, resacetophenone-, peonol- and 2-hydroxy-1-naphthaldoximes have been ma     

Analytical characteristics of near-infrared nonmetal atomic emission from a helium microwave-induced plasma

Relative emission intensities for several atomic lines of C, N, O, F, S, Cl and Br between 700 and 1200 nm in an atmospheric-pressure helium microwave-induced plasma are reported. For each element the most intense near-infrared lines are compared to the most intense u.v.-visible lines in terms of signal-to-background ratios and spectral interferences. The relative-intensity data are used to calculate excitation temperatures for each element.     

Near-infrared nonmetal atomic emission from a helium microwave-induced plasma: element ratio determinations

The utility of near-infrared atomic emission lines of C, F, S, Cl and Br for the determination of element ratios in organic compounds is evaluated. An atmospheric-pressure helium microwave-induced plasma is used to fragment sample molecules and excite their constituent atoms. The effects of plasma operating parameters such as power and flow rate, as well as the effects of spatial viewing position and plasma length are also investigated.