Specializing in chemical analysis using mass spectrometry, & glow discharge trace element analysis laboratories. In fact, it is possibly the oldest form of MS. Electric discharges were commonly used as “natural” ion sources in the 1920s and 1930s for the early mass spectrographs [198], Much of the early analytical work in GD-MS was aimed at replacing the spark ion source (a vacuum discharge ionization source that yields broad energy spreads, an erratic ion beam and usually unreliable quantitative results). If attention is focused on only one, or a few impurities, more sensitive techniques such as sputter initiated resonant ion spectroscopy may be appropriate (Tower et al., 1996; Sen et al., 1996). Further applications of GDMS include the analysis of zirconium alloys, which are used as cladding materials for nuclear fuel elements. Reprinted from Jakubowski N and Stüwer D (1989) Comparison of Ar and Ne as working gases in analytical glow discharge mass spectrometry. Control of purity has been described in Section 2. Here, the main interest is the isotopic composition of all types of declared or undeclared nuclear materials with respect to U and Pu isotopes. Our testing labs perform trace element analysis & material testing for non-organic trace elements. Atomic Spectroscopy. It was shown that, for several elements, the RSFs strongly depend on the oxygen content in the sample (Betti 1996), which implies a specific matrix reference sample for the quantitative analysis of oxygen-containing samples. Betti and coworkers detected trace and ultratraces of radioisotopes in soils, sediments, and vegetation by GDMS (Betti et al., 1996). Although ions are formed throughout the source cell, only those created very close to the exit orifice can survive to the high-collision environment and depart in the charged state. The maximum doping levels achievable in bulk CdTe are of some 1017 cm−3 for holes (As, P, Li) and about 1018 cm−3 for electrons (Al, I, In), very close to the deviations from stoichiometry on both Cd and Te sides. It is demonstrated that both discharge gases exhibit similar analytical performance if a correspondingly higher pressure is used for neon; and hence, specific interference problems can be overcome. Cd was also suspected to be the main source of Cu contamination for residual levels in the 1–40 ppba range [273]. The holder is mounted to the end of the DIP and comprises a PTFE clamp assembly, support rods, boron nitride spacers and either stainless steel or aluminium anode orifice plates. With glow discharge spectrometry, sample material is uniformly sputtered from the surface. The cathode surface consisting of the sample material is sputtered by Ar+ ions, which are formed in low-pressure argon plasma and accelerated toward the cathode. 8.15. The growth process is the primary area of concern. Mainly Al, Ga, In, Cl, and I have been used as donors and Li, Cu, Ag, N, P, and As as acceptors. A common problem in GDMS, as in most mass spectrometric methods, is the occurrence of spectral interferences in the mass spectrum, e.g. : Max-Planck-Gesellschaft, Hechingen, Ger. In this work, certified marine sediment doped with 237Np was used for the calibration strategy. The anode body in this case is the Ta ion volume enclosed by the anode plate and the ion exit orifice mounted to it; the entire cell assembly is affixed to the commercial source cryo-cooling ring. Even if one could separate both peaks with a high-resolution mass spectrometer (a resolution of M/ΔM = 7620 is required), the tailing of the huge cluster peak would prevent one from reaching low limits of detection for rhodium. A prepared flat sample is mounted on the glow discharge source, the source is evacuated and backfilled with argon. It is capable of analyzing, conducting, semi … Both, initial raw materials and fuel pellets were studied (De la Heras et al., 2000). The plasma conditions ensure an efficient dissociation and atomic ion formation by Penning and/or electron impact ionization. Thus, the sample must be transported to the cell volume through a vacuum interlock system by means of a direct insertion probe (DIP). Miroslav Ješkovský, ... Pavel P. Povinec, in Handbook of Radioactivity Analysis: Volume 2 (Fourth Edition), 2019. The Finnigan ELEMENT GD, a combination of a glow discharge ion source with a high resolution mass spectrometer, is the ultimate tool for the direct analysis of conductive materials. The sputtered material is then atomized and excited in a low-pressure plasma discharge, away from the sample surface. It is also frequently applied to the characterization of nuclear samples (Betti, 1996) as well as nuclear forensics (Betti et al., 1999). Fig. neon instead of argon. It has found widespread applications in the determination of trace-level distributions at surfaces and within conducting and nonconducting solids or dispersed liquids (Duckworth et al., 1993; Barshick et al., 1993, 2000). In another study, such acceptors as Li, Na, K, As, Cu, Ag, Sb, and Bi, donors as Al, Cl, Ga, In, and Tl, and neutral elements as Si, Ca, Cr, Co, Sn, and Pb, were identified as classical residual impurities in as-grown p-type VB CdTe crystals [274]. The precise and accurate measurement of isotope ratios is a further application of GDMS, which is of high relevance, for example, in nuclear forensics. Although impurities are introduced during growth, the Bridgman process tends to segregate them to the last-to-freeze end. The titanium specimen to be analyzed may be in the form of a disk, casting, foil, sheet, plate, extrusion or some other wrought form or shape. The growth process is the primary area of concern. The primary application of the Astrum GD-MS is the characterisation of … L’alimentation pulsée des sources à décharge luminescente permet une ionisation plus efficace à des taux de projection plus bas. Quantitative data on these zircaloy cladding materials were obtained in agreement by applying either matrix specific or RSF values for a uranium metal sample. Oxygen as a major element in the matrix causes problems due to its release during the discharge process. Ion source designs for (A) pin and (B) flat sample types in rfGD-MS. With samples less than 5 mm in diameter, the flat sample holder depicted in Fig. 8.15 are intended to afford great flexibility and allow the use of the same DIP for the actual sample insertion. Glow Discharge Spectrometry utilizes a low-pressure, non-thermal process in which material is uniformly sputtered from the sample surface by a stream of argon ions. ), Glow Discharge Mass Spectrometry, Methods, Encyclopedia of Spectroscopy and Spectrometry, Jacques L'. To illustrate this, Figure 7 presents a part of the mass spectrum (m/z 90–100) of a pure iron sample, both in argon and in neon. Control of stoichiometry during growth, e.g., by providing a cadmium reservoir, can influence the uptake and activation of impurities through second phases and vacancies. Glow Discharge Mass Spectrometry (GDMS) is one of the most powerful solid state analytical methods for the direct determination of traces, impuri-ties and depth profiling of solids.1–5 Glow discharge mass spectrometers, which are commercially available with fast and sensitive electrical ion detec- Nonconductive nuclear samples, especially oxide-based compounds such as uranium and plutonium oxide samples, are investigated by GDMS (Betti, 1996; Betti and de las Heras, 2004). 8.3. The surface oxides on the high-purity elements, the residual gases, and the hydrocarbon vapors from the evacuation system were identified as well as sources of contamination from infrared absorption experiments [121]. The fundamental aspects of the glow discharge (GD) plasma will be briefly discussed, as well as the different source configurations, operational modes, and mass analyzers employed for the generation of a GD ionization source and the analysis of a multitude of matrices. Glow-discharge-mass spectrometry (GD-MS) has received increasing attention over the last decade. Unsurprisingly, it has developed into the most prominent GD coupling. Figure 8.3. The Ar+ ions are accelerated by the source potential of a few hundred volts and sputter off sample constituents as atoms, ions, molecules, and clusters. Although sputtering and ionization occurs at a different location in different times of the instrument, matrix effects are minimized and calibration with quantification of the device is much simplified. The cell dimensions were found not to affect the plasma quantities qualitatively but only as regards their absolute values. In this way, GDMS meets the requirements for bulk solids analysis in nuclear systems, providing a full elemental analysis at major, minor, and trace concentration levels with lowest matrix dependency (Robinson and Hall, 1987). Créer un compte, Learn new insight on SARS-CoV-2 Immune Response. FIGURE 13.5. Johanna Sabine Becker, in Handbook of Radioactivity Analysis (Third Edition), 2012. The rf-powered DIP must meet several design requirements including efficient coupling of the rf power to the sample, isolation of the sputtering to the sample surface and effective shielding of potential radiated power losses. 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