Isotopic abundance measurements on solid nuclear-type samples by glow discharge mass spectrometry

A double-focusing Glow Discharge Mass Spectrometer (GDMS) installed in a glovebox for nuclear sample screening has been employed for isotopic measurements. Isotopic compositions of zirconium, silicon, lithium, boron, uranium and plutonium which are elements of nuclear concern have been determined. Interferences arising from the matrix sample and the discharge gas (Ar) for each of these elements are discussed. The GDMS results are compared with those from Thermal Ionization Mass Spectrometry (TIMS). For boron and lithium at microg/g-ng/g levels, the two methods gave results in good agreement. In samples containing uranium the isotopic composition obtained by GDMS was in agreement with those from TIMS independently of the enrichment. Attempts for the determination of plutonium isotopic composition were also made. In this case, due to the interferences of uranium at mass 238 and americium at mass 241, the GDMS raw data are complementary with those values obtained from physical non-destructive techniques.     

Isotopic abundance measurements on solid nuclear-type samples by glow discharge mass spectrometry

A double-focusing Glow Discharge Mass Spectrometer (GDMS) installed in a glovebox for nuclear sample screening has been employed for isotopic measurements. Isotopic compositions of zirconium, silicon, lithium, boron, uranium and plutonium which are elements of nuclear concern have been determined. Interferences arising from the matrix sample and the discharge gas (Ar) for each of these elements are discussed. The GDMS results are compared with those from Thermal Ionization Mass Spectrometry (TIMS). For boron and lithium at g/g-ng/g levels, the two methods gave results in good agreement. In samples containing uranium the isotopic composition obtained by GDMS was in agreement with those from TIMS independently of the enrichment. Attempts for the determination of plutonium isotopic composition were also made. In this case, due to the interferences of uranium at mass 238 and americium at mass 241, the GDMS raw data are complementary with those values obtained from physical non-destructive techniques.     

Detection of negative ions in glow discharge mass spectrometry for analysis of solid specimens

A new method is presented for elemental and molecular analysis of halogen-containing samples by glow discharge time-of-flight mass spectrometry, consisting of detection of negative ions from a pulsed RF glow discharge in argon. Analyte signals are mainly extracted from the afterglow regime of the discharge, where the cross section for electron attachment increases. The formation of negative ions from sputtering of metals and metal oxides is compared with that for positive ions. It is shown that the negative ion signals of F^? and TaO₂F^? are enhanced relative to positive ion signals and can be used to study the distribution of a tantalum fluoride layer within the anodized tantala layer. Further, comparison is made with data obtained using glow-discharge optical emission spectroscopy, where elemental fluorine can only be detected using a neon plasma. The ionization mechanisms responsible for the formation of negative ions in glow discharge time-of-flight mass spectrometry are briefly discussed.     

Depth profiling of frictional brass coated steel samples by glow discharge mass spectrometry

Chemical depth profiles of frictional brass layers processed on steel substrates were performed using glow discharge mass spectrometry. Due to the continuously varying concentrations of zinc, copper and iron in the frictional layers a linear combination of the relative sensitivity factors and sputter rates of the pure iron and brass matrix was used to quantify the depth profiles. The quantified data indicate a non-stoichiometric copper content of the investigated layers.     

Analysis of solution residues by glow discharge mass spectrometry

A technique for the analysis of microliter volumes of solution by glow discharge mass spectrometry (GDMS) has been successfully demonstrated. Cathode preparation involves mixing an aliquot of the sample solution with a pure conducting powder, followed by drying and pressing before conventional GDMS analysis. The analyte signal at the 100-ppm level was observed to be stable to better than 5% for the duration of the analysis (30–45 min). Internal and external reproducibilities were better than 5%, and the ion signal intensity was linear with concentration over at least four orders of magnitude. Quantification was demonstrated by means of user-defined relative sensitivity factors. Relative standard deviations were better than 15% for the elements investigated, with no preconcentration of the analyte.     

Multielemental characterisation of cobalt by glow discharge quadrupole mass spectrometry

Multielemental determination and the assessment of purity of cobalt metal used in the preparation of Ni-based super-alloys have been carried out by glow discharge quadrupole mass spectrometry (GD-QMS). Relative sensitivity factors (RSF) generated from certified iron matrix reference samples (NIST 663 and 664 low alloy steel pin standards) could be used for the determination of different trace element constituents of the sample. Different wet chemical procedures were also carried out for the determination of the trace constituents in the sample. The GD-QMS results are in reasonably good agreement with those obtained from wet chemical procedures, validating the use of the RSF values generated on low alloy steel standards for the computation of trace element concentrations in cobalt metal. A variety of molecular ions formed through the reaction of cobalt (matrix) with the discharge gas (argon) were also detected.     

Measurement of isotope ratios in solids by glow discharge mass spectrometry

A commercial thermion mass spectrometer has been modified for glow discharge mass spectrometry. GDMS isotope ratio measurements on osmium, uranium, and boron containing samples are compared with TIMS measurements.     

The use of a secondary cathode to analyse solid non-conducting samples with direct current glow discharge mass spectrometry: potential and restrictions

A direct current glow discharge mass spectrometer has been used to analyse solid non-conducting samples: glass, polycarbonate, marble, aluminium oxide and Teflon. This is made possible by the use of a so-called secondary cathode. The methodology of this concept is investigated and analytical figures of merit are presented.     

The use of a secondary cathode to analyse solid non-conducting samples with direct current glow discharge mass spectrometry: potential and restrictions

A direct current glow discharge mass spectrometer has been used to analyse solid non-conducting samples: glass, polycarbonate, marble, aluminium oxide and Teflon. This is made possible by the use of a so-called secondary cathode. The methodology of this concept is investigated and analytical figures of merit are presented.     

On copper diffusion in silicon measured by glow discharge mass spectrometry

Copper contamination occurs frequently in silicon for photovoltaic applications due to its very fast diffusion coupled with a low solid solubility, especially at room temperature. The combination of these properties exerts a challenge on the direct analysis of Cu bulk concentration in Si by sputtering techniques like glow discharge mass spectrometry (GDMS). This work aims at addressing the challenges in quantitative analysis of fast diffusing elements in Si matrix by GDMS. N-type, monocrystalline (Czochralski) silicon samples were intentionally contaminated with Cu after solidification and consequently annealed at 900 °C to ensure a homogeneous distribution of Cu in the bulk. The samples were quenched after annealing to control the extent of the diffusion to the surface prior to the GDMS analyses, which were carried out at different time intervals from within few minutes after cooling onward. The Cu profiles were measured by high-resolution GDMS operating in a continuous direct current mode, where the integration step length was set to ～0.5 μm over a total sputtered depth of 8–30 μm. The temperature of the samples during the GDMS analyses was also measured in order to evaluate the diffusion. The Cu contamination of n-type Si samples was observed to be highly material dependent. The practical impact of Cu out-diffusion on the calculation of the relative sensitivity factor (RSF) of Cu in Si is discussed.     

Cryogenically cooled sample holder for polymer sample analysis by radiofrequency glow discharge mass spectrometry

A cryogenically cooled sample holder has been constructed for use in the analysis of polymeric materials by radio frequency glow discharge mass spectrometry (rf-GDMS). Passage of liquid nitrogen through the body of a brass sample backing plate cools the sample down to temperatures of approximately ?170°C. The cryo-cooled sample holder is readily adaptable to existing direct insertion probe assemblies commonly used in GDMS instrumentation. The benefits of low temperature cooling are illustrated in terms of the ability to analyze thermally sensitive polymers without evidence of degradation, greater temporal stability of the ion signal, and the reduction of proton transfer reactions to polymer fragment species (due to the presence of residual water vapor). Implementation of the cryo-cooled sample holder opens up many possibilities for the direct analysis of solid polymers by rf-GDMS.     

Analysis of semiconducting materials by high-resolution radiofrequency glow discharge mass spectrometry

The analytical capabilities of a high-resolution mass spectrometer in combination with a 13.56 MHz glow discharge ion source for the analysis of semiconducting materials (silicon carbide and gallium arsenide) were studied. It was shown that single positively charged ions of sample material have about 10 eV higher average energy than the ions of the discharge and residual gas. Therefore effective energy separation of the ions of analyte from the ions of the discharge and residual gas was achieved by adjusting the ion transfer optics (breadth and position of energy slit), which improves the analytical capabilities of the developed method.Some analytical applications are presented to illustrate the performance of r.f. GDMS for the bulk analysis of semiconducting materials. The results of the trace element analysis of gallium arsenide and silicon carbide samples are compared with data of independent methods (LIMS, ICP-AES, SIMS).Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthdayOn leave from the Institute of Inorganic Chemistry, 630090 Novosibirsk, Russia     

Comparison between the use of direct current glow discharge mass spectrometry and inductively coupled plasma quadrupole mass spectrometry for the analysis of trace elements in nuclear samples

The quantitative determination of trace elements in nuclear samples by GDMS and ICP-MS is presented and compared. Spectral interferences, matrix effects, detection limits, precision and accuracy are discussed. Results for selected samples demonstrated that both techniques are complementary. The use of a multi-standard solution provides the most accurate results in ICP-MS, whereas in GDMS this is achieved by relative sensitivity factors (RSF) matrix matched. Nevertheless, the use of standard RSF allows a fast screening.     

Comparison between the use of direct current glow discharge mass spectrometry and inductively coupled plasma quadrupole mass spectrometry for the analysis of trace elements in nuclear samples

The quantitative determination of trace elements in nuclear samples by GDMS and ICP-MS is presented and compared. Spectral interferences, matrix effects, detection limits, precision and accuracy are discussed. Results for selected samples demonstrated that both techniques are complementary. The use of a multi-standard solution provides the most accurate results in ICP-MS, whereas in GDMS this is achieved by relative sensitivity factors (RSF) matrix matched. Nevertheless, the use of standard RSF allows a fast screening.     

A glow discharge device for atomic emission spectrometry of microliter solution samples

A novel glow discharge device designed specifically for solution analysis is described. The detection limits obtained are comparable to those obtained with demountable hollow cathode lamps, but with better precision. Rotational and excitation temperatures are examined as functions of fill gas pressure and discharge current. A sputtering constant is presented and the technique for measuring this parameter is described.     

A novel isotope analysis of oxygen in uranium oxides: comparison of secondary ion mass spectrometry,glow discharge mass spectrometry and thermal ionization mass spectrometry

The natural variation of the oxygen isotopic composition is used among geologists to determine paleotemperatures and the origin of minerals. In recent studies, oxygen isotopic composition has been recognized as a possible tool for identification of the origin of seized uranium oxides in nuclear forensic science. In the last 10 years, great effort has been made to develop new direct and accurate n(¹⁸O)/n(¹⁶O) measurements methods. Traditionally, n(¹⁸O)/n(¹⁶O) analyses are performed by gas mass spectrometry. In this work, a novel oxygen isotope analysis by thermal ionization mass spectrometry (TIMS), using metal oxide ion species (UO⁺), is compared to the direct methods: glow discharge mass spectrometry (GDMS) and secondary ion mass spectrometry (SIMS). Because of the possible application of the n(¹⁸O)/n(¹⁶O) ratio in nuclear forensics science, the samples were solid, pure UO₂ or U₃O₈ particles. The precision achieved using TIMS analysis was 0.04%, which is similar or even better than the one obtained using the SIMS technique (0.05%), and clearly better if compared to that of GDMS (0.5%). The samples used by TIMS are micrograms in size. The suitability of TIMS as a n(¹⁸O)/n(¹⁶O) measurement method is verified by SIMS measurements. In addition, TIMS results have been confirmed by characterizing the n(¹⁸O)/n(¹⁶O) ratio of UO₂ sample also by the traditional method of static vacuum mass spectrometry at the University of Chicago.     

辉光放电质谱法测定高纯铟中痕量元素

采用辉光放电质谱法(GDMS)对高纯铟中铁、铜、铅、锌、铊、镉、锡等14种元素进行了测定,对仪器工作参数进行了优化,对预溅射过程时间的确定和质谱干扰的排除进行了讨论,结果表明,GDMS是目前具有足够灵敏度对高纯导电材料进行直接分析的有效手段。     

辉光放电质谱法测定钨钛合金中的微量杂质元素EI北大核心CSCD

采用辉光放电质谱法直接测定钨钛合金中的杂质元素。对放电电流、气体流量和预溅射时间等条件进行优化,用仪器内置的标准相对灵敏度因子(RSFstd)进行半定量分析。同时用已定值的钨钛合金作为标样校正仪器,获得校正后的相对灵敏度因子(RSFWTi),再应用于定量分析。结果表明,未校正测量值与参考值比值在0.5~1.6之间,相对标准偏差(RSDs)小于5%,满足半定量分析要求。经RSFWTi校正的测量值与电感耦合等离子体质谱法(ICP-MS)测得的结果比较,相对偏差(RD)小于20%,该方法适用于合金中杂质元素定量分析。