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A method of slurry nebulization for inductively coupled plasma optical emission spectrometry (ICP-OES) applied to the analysis of titanium niride(TiN) was reported. The TiN slurry sample was prepared with adding dispersant polyacrylate amine or polyethylene imine for the stabilization and homogenization of suspension, and the amount of additives was optimized. A Babington type cross-flow nebulizer with V-groove was used for nebulization of the slurry for avoidance of blockage from the particles. The stability of slun-y was characterized via zeta potential measurement, scanning electron microscope observation, particle size distrbution measurement and signal stability testing. For nm size TiN, calibration curves could be established by aqueous standards and the analytical results were in good accordance with the alkaline fusion method. For μ m size TiN, a negative deviation was observed for most of elements and this deviation can be corrected by using Ti intrinsic internal standard method. © 2005 Elsevier B.V. All rights reserved.

False-color spatial maps of experimentally determined and simulated values of electron number density ( n e ), electron temperature ( T e ) and heavy-particle temperature ( T g ) for an argon inductively coupled plasma (ICP) in the plasma decay region (tail flame) are compared in detail. Experimental and theoretical values are in general very consistent; the difference between experiment and computation is approximately 10% for n e and T e and 20% for T g in the plasma region examined. The errors in n e and T e are larger at the edge of the plasma, most likely because air entrainment becomes significant. This comparison provides a link between measurements and the current mathematical model and serves to partially validate both methods. Sources of error in both experiment and theory are considered and discussed.

A thermospray nebulizer was used as a sample introduction device for microwave plasma torch (MPT) atomic emission spectrometry (AES). Experimental parameters, including the power supplied to the MPT, the flow rates of support and carrier gases, the observation height, the sample uptake rate, the thermospray working temperature, the temperature of the aerosol spray chamber and cooling water were optimized. Under optimum conditions, the relative standard deviation (RSD) of 10 measurements for 21 elements is in the range 0.3–2.0%. The detection limits were improved in comparison with the ultrasonic nebulizer as sample introduction technique for MPT–AES. The inclusion of 20% methanol into the MPT showed there is no effect on the stability of MPT discharge. The technique can thus be held to have the potential for interface to reverse-phase HPLC systems.

This work evaluates the possibilities of applying microsecond-pulse glow discharge time of flight mass spectrometry (μs-pulse GD-TOFMS) in surface depth analysis. Investigations have been done for effects of discharge pressure on sputtered depth profiles as well as on topographies under μs-pulse GD mode; and also for influences of discharge current and discharge frequency on characteristics of sputtered surface. Sputtering rates of several pure metals under μs-pulse GD and dc-GD modes were studied and compared. The estimated erosion rates are 1.27, 2.90 and 5.18 nm s −1 for pure Fe, Cu and Zn layer, respectively. Depth profiling were conducted for a technical Zn–Fe layer (about 10 μm) and for a Fe–Cu layer (about 1 μm) by μs-pulse GD. A simple model was developed and utilized to convert ion intensity into element concentration, and the experimental results were presented and discussed. Preliminary results show that μs-pulse GD-TOFMS has a promising future in the area of surface depth analysis, especially in the depth analysis of thin layers and of their cross-sections.

The rare earth elements (REEs) play very important roles in industrial manufacturing, technology development and biological processes. Due to their complex emission spectra, trace levels of REEs are difficult to analyze by conventional ICP-AES techniques. The present study investigates possible spectral interferences of matrices (rare earth oxides of Ce, Pr, Nd, Sm and Dy) on the analytical lines (± 0.1 nm) of a target REE. Detailed and well-resolved spectra for selected REEs are presented, and procedures used to rectify the problem of spectral interferences caused by REE matrices are discussed. A computer-assisted system (CAS) for spectral recognition has been developed and used to assist in the study of matrix interference. To determine directly trace rare earth elements in REE matrices without sample pre-separation, the application potential is demonstrated with a one meter sequential instrument retrofitted with a 3600 grooves/mm grating.

This paper describes a new type of glow discharge (GD) ion source coupled to a time-of-flight mass spectrometer (TOFMS). The GD is operated in the microsecond pulse (μs-pulse) mode. The operational parameters of the μs-pulse GD were optimized against the ion signals, giving 180 Pa for the discharge pressure, 3 A for the transient discharge current, 1.75 kHz for the discharge frequency and 2 μs for the discharge pulse duration. Experimental results show that the discharge current in the μs-pulse mode can be one order of magnitude higher than that obtained in the d.c. mode. The structure of the interface between the μs-pulse GD and the mass spectrometer was found to be critical, and a Macor disc must be applied in front of the sampling orifice in order to shield the sampling plate from the anode of the GD to achieve both a good vacuum and the best sputtering. A transient sputtering rate of 24.4 μs s−1 mm−2 was reached in the μs-pulse mode and was significantly higher than that for the d.c.-GD. Typical mass spectra of brass and nickel samples were studied and are discussed. © 1997 Elsevier Science B.V.

A transient data acquisition system for flow injection analysis (FIA), high performance liquid chromatography (HPLC), and electrothermal vaporization (ETV) combined with ICP-AES multi-element instrumentation was developed and successfully applied to the analysis of different types of samples, including human serum, human hair and tea, for simultaneous multi-element determinations. The accuracy of the method was verified with hair reference material. Good agreement between the experimental results and certified values, and also satisfactory recoveries from standard additions, were achleved.

This paper is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta, Part B (SAB). This hardcopy text, comprising the main body and an appendix, is accompanied by a disk with programs, data files and a brief manual. The main body discusses purpose, design principle and usage of the computer software for the inductively coupled plasma atomic emission spectrometry (ICP-AES) expert system. The appendix provides a brief instruction on the manipulation of the demonstration program and relevant information on accessing the diskette. The computer software of the expert system has been developed in C++ language to simulate spectra and to select analytical lines in ICP-AES. This expert system is based on a comprehensive model of non-LTE ICP-AES, which includes expertise in plasma discharges, analyte ionization and excitation, and spectral-line shapes. The system also provides several databases in which essential elemental and spectral data are stored. A logic reasoning engine is utilized for selection of the best analytical line with a main criterion of minimizing the true detection limit. The system is user-friendly with pop-up menus, an editor for database operation, and a graphic interface for the display of simulated spectra. The system can simulate spectra and predict spectral interferences with good accuracy.

Spectra and spectral interferences in inductively coupled plasma-atomic emission spectrometry, ICP-AES, have been simulated and predicted by a primary expert system under contrasting conditions of local temperature equilibrium (LTE) and non-LTE. In this expert system a comprehensive computer model has been applied to provide expert knowledge on an non-LTE ICP discharge, analyte ionization and excitation, and spectral line shape. The system also includes several databases to supply the calculation with spectral and elemental parameters. Some typical examples are illustrated, with satisfactory outcomes. It is found that predictions under non-LTE conditions are much closer to the reality than those under LTE conditions.

The effects of adding foreign gases to the central-gas flow or the intermediate-gas flow of an argon inductively coupled plasma are presented. In particular, the influence of up to 16.7% added helium, nitrogen or hydrogen on radially-resolved electron number density, electron temperature, gas-kinetic temperature and calcium ion emission profiles is examined. It is shown that these gases affect not only the fundamental parameters and bulk properties of the plasma, but also how energy is coupled and transported through the discharge and how that energy interacts with the sample. For example, added helium causes an increase in the gas-kinetic temperature, most likely due to the higher thermal conductivity of helium compared to argon but, in general, does not appear to affect significantly either the electron temperature or electron concentration. The shift in the calcium ion emission profile towards lower regions in the discharge with added helium may be attributable to higher droplet desolvation and particle vaporization rates. In contrast, the addition of nitrogen or hydrogen to an Inductively Coupled Argon Plasma (Ar ICP) results in dramatic changes in all three fundamental plasma parameters: electron number density, electron temperature, and gas-kinetic temperature. The net effect of these molecular gases (N2 or H2) on calcium ion emission and on the fundamental plasma parameters is shown to be dependent on the amount of gas added to the plasma and whether the gas is introduced as part of the central- or intermediate-gas flow. In general, nitrogen added to the central-gas flow causes a significant reduction in the number of electrons throughout most of the discharge (over an order of magnitude in certain regions), mainly in the central and upper zones of the ICP. A drop of 3000–5000 K in the central channel electron temperature and a smaller drop in the gas-kinetic temperature are also observed when N2 is added to the central-gas flow. In contrast, the introduction of nitrogen in the intermediate flow causes about a 1 × 1015 electrons cm−3 increase in the electron concentration in the low, toroidal regions of the plasma and an increase in the gas-kinetic temperature of around 1000 K throughout most of the discharge. As seen with the addition of nitrogen to the central-gas flow, the electron temperature is found to increase in the toroidal zones of the plasma when N2 is added to the intermediate flow. These combined effects cause a 20-fold depression in the calcium ion emission intensity only a 1.7-fold depression when N2 is added to the central- or intermediate-gas flows, respectively. On the other hand, hydrogen causes a depression in the electron concentration in the upper areas of the plasma when this gas is added to the central flow but increases the number of electrons in the same region when added to the intermediate flow. Hydrogen also causes a dramatic effect on the electron and gas-kinetic temperatures, significantly increasing both of these parameters throughout the discharge. An increase in the calcium ion emission intensity, accompanied by a downward shift, elongation and broadening of the calcium ion emission profile is also observed with H2 addition.

Isocontour maps of electron temperature (Tc), electron number density (nc, and gas-kinetic temperture (Tg) in an argon inductively-coupled plasma (ICP), have been constructed for five rf power settings and in the presence and absence of an aqueous aerosol, based on the simultaneous measurement of spatially resolved Thomson and Rayleigh scattering. Each map was assembled from 21 observation heights and 31 radial positions, the location of each point being controlled by a computer-driven three-axis translation stage. The maps demonstrate how Te,ne and Tg all increase throughout the plasma as rf power is raised, with the electron number density increasing most rapidly. At greater rf power levels (1.75 kW), the introduction of an aqueous aerosol into the central channel was found to increase ne over the entire plasma. In contrast, at lower applied power (0.75 kW), nc is depressed throughout the discharge upon the introduction of water aerosol. At intermediate rf powers (1.0, 1.25 and 1.5 kW), aerosol introduction raises nc only in the regions near the hot torus, while reducing nc at all other spatial positions, particularly lower in the central channel. Aerosol introduction was found also to thermalize the plasma at all rf power settings by increasing Tg in the higher regions and decreasing Te lower in the central channel. In general, Te is substantially higher than Tg in the lower regions of the discharge, but the two approach each other in the upper zones.

Langmuir probe measurements were performed in the first vacuum stage of an inductively coupled plasma mass spectrometer as source and interface conditions were adjusted. Space and floating potentials were found to increase with first-stage backing pressure, inner-gas flow rate, and solvent load. When the probe was located at the skimmer-cone-orifice position (with the skimmer cone removed), the space and floating potentials were found to be positive, which indicates that the plasma is no longer quasi-neutral. Additional experiments involved spatial mapping of the floating potentials in the expansion zone. In this zone, measured electrostatic potentials followed the geometrical features of a free-jet expansion expected for a neutral gas. This correlation indicates that neutral flow influences the electrostatic features in the shockwave structure of the expansion.

A non-commercial inductively coupled plasma-mass spectrometry (ICP-MS) instrument is used to compare a center-tapped ICP load-coil geometry with the standard inverted-coil arrangement. This direct comparison on the same ICP-MS unit shows that the load coil exerts only a minor influence on analytical characteristics such as sensitivity, doubly charged ion and oxide-ion ratios, and detection limits. The influence of operating parameters (nebulizer flow rate, sampling depth, generator rf frequency and applied power) on analyte-ion signals and oxide-ion ratios similarly appears to be independent of the load coil. However, the load-coil geometry is found to dictate the particular nebulizer flow rate, sampling depth, and biaspotential setting that are optimal and how these parameters affect doubly charged ion ratios and backgroundion signal magnitudes. Also, there is a greater loss in sensitivity for higher-mass elements with the center-tapped unit.

A 20-Hz frequency-doubled Q-switched Nd : YAG laser has been used to measure Thomson-scattering spectra from an inductively coupled argon plasma (ICP). The experimental data were treated with a non-linear regression curve-fitting program to determine electron temperatures and electron number densities under different plasma operating conditions. A comparison of the measured Thomson-scattering spectra with the corresponding fitted curves indicates that the electron energy distributions in the ICP are very close to Maxwellian under a wide range of sample-introduction conditions and at locations above, below, and at the tip of the “bullet”. As a result, electron temperature can be used as a meaningful fundamental parameter. The theory used in this study is briefly reviewed and the detailed experimental considerations are described.

The detection limits for 38 elements in a low-power (2 kW) oxygen inductively coupled plasma (ICP) are found to be a factor of 10 inferior to those in an argon ICP as reported by winge et al. [ Appl. Spectrosc. 33 , 206 (1979)], but better than in an air or nitrogen ICP. A 14-times improvement of the signal-to-background ratio has been achieved in the determination of barium in a CaO powder sample in the oxygen ICP compared to that in the argon ICP.

A low-power (2kW) oxygen inductively coupled plasma is simulated by an advanced computer modeling technique. The effects of frequency, gas flow rate, and power are investigated. The results show that a stable low-power oxygen ICP can be sustained in a conventional torch. A temperature as high as 12000 K in ths plasma core is predicted. The plasma shape defined by the temperature region with 5000 K is narrower than an argon plasma as a result of a thermal-pinch effect. The Lorentzian force and outer gas swirl play important roles in the plasma stability.

A two-dimensional computer model has been applied in the simulation of an analytical inductively coupled plasma (ICP) discharge. The temperature and flow fields as well as the electromagnetic field in an argon ICP discharge operated at 40 MHz and 1 kW have been investigated. The results are compared with those obtained with an earlier model.

Noise amplitude spectra for the signal from an inductively coupled plasma-mass spectrometer (ICP-MS) were measured and compared with those obtained with inductively coupled plasma-atomic emission spectrometry (ICP-AES). For the ICP-MS, white noise was dominant in background spectra. An audio-frequency noise peak at 200–350 Hz was observed and behaved much like the one noted earlier in ICP-AES. Unlike in ICP-AES, however, the frequency at which this noise peak occurs is dependent upon the sampling depth in the plasma.

A modified Abel inversion technique is described for a line width calculation, based on the relationship between the lateral and radial line profile in a cylindrical light source. The technique is examined with a simulated radial emission profile and line width. The errors introduced in the improved technique also are discussed.

Self-consistent electron and excitation temperatures, the electron number density, and intensity ratios of ion to atom lines in a low-power oxygen inductively coupled plasma (ICP) were measured. The experiments were conducted by means of absolute intensities of argon line and continuum emissions, Fe I species population distribution with respect to energy levels, H α line broadening, and line emissions of Ca and Cd analytes, respectively. The experimental results are found to be close to the LTE values, indicating that the features of the low-power oxygen ICP can be described by an LTE model.