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1.
The aim of this work was the preparation of samples with thorium on the steel discs by electrodeposition for determination of natural thorium by alpha spectrometry and for following analysis by secondary ion mass spectrometry. The samples with 232Th isotope were prepared by electrodeposition from solution Th(NO3)4·12H2O on steel discs in electrodeposition cell with use of solutions of Na2SO4, NaHSO4, KOH and ammonia oxalate by electric current of 0.75 A. Weights of electrodeposited thorium samples were calculated on the basis of intensities of peak of 232Th isotope in the alpha spectra. The layer thickness was calculated for following analysis of surface layers of thorium using secondary ion mass spectrometry.  相似文献   

2.
Electrodeposited natural uranium films prepared by electrodeposition from solution of uranyl nitrate UO2(NO3)2·6H2O on stainless steel discs in electrodeposition cell. Solutions of NaHSO4, and Na2SO4 and electric current from 0.50 up to 0.75 A were used in this study. Recalculated weights and surface’s weights of 238U from the alpha activities and secondary ion mass spectrometry (SIMS) intensities resulted in a linear regression. A dependency between of 238U surface’s weights recalculated from alpha activities and signal intensity of 238U in SIMS was investigated in order to determine a potential of SIMS in quantitative analysis of surface samples containing uranium. In the SIMS spectra of electrodeposited uranium films we found that upper layer consist not only from isotopes of uranium (ions 234U+, 235U+, and 238U+). In the positive polarity SIMS spectra, various molecules ions of uranium were suggested as UH+, UH2 +, UO+, UOH+, UO2 +, UO2H+, UO2H2 +, as well as possibly ions UNO+ and UNOH+.  相似文献   

3.
The SIMS method has been used for studying the time dependent intensities of the secondary ions H2O+, O+, CH 3 + and C+ under Ar+ bombardment of two CCF samples with different packing of filaments. The thickness of defect layers is estimated from the median of secondary ions distribution.  相似文献   

4.
For more than three decades, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) has been used for elemental depth profiling. In recent years, cluster primary ion sources (principally, C60+, Bin+, and Aun+) have become widely available, and they can greatly enhance the signal intensity of molecular ions (10–1000 times). Understanding the performance of cluster ion analysis beams used in elemental depth profiling can greatly assist normal ToF‐SIMS users in choosing the optimal analysis beam for depth profiling work. Presently, however, the experimental data are lacking, and such choices are difficult to make. In this paper, hydrogen and deuterium depth profiling were studied using six different analysis beams—25 keV Bi+, Bi3+, Bi5+, 50 keV Bi32+, 10 keV C60+, and 20 keV C602+. The effort shows that cluster primary ions do enhance H? and D? yields, but the enhancement is only about 1.5–4.0 times when compared to atomic Bi+ ions. Because the currents of atomic ion analysis beams are much stronger than the currents of cluster ion analysis beams for most commercial ToF‐SIMS instruments, the atomic ion analysis beams can provide the strongest H? and D? signal intensities, and may be the best choices for hydrogen and deuterium depth profiling. In addition, two representative nuclides, 30Si and 18O, were also studied and yielded results similar to those of H? and D?. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

5.
Secondary ion mass spectrometry (SIMS) has been used to detect the reactions induced by active ion bombardment (AIB) of N+2 on surfaces of pyrolytic graphite and a (100) Si crystal. The SIMS spectra exhibit ions of CN?, HCN?, HnC2N?(n = 2, 3, 4), HN?, and SiN?, indicating that reactions take place with the graphite and silicon as well as adsorbed hydrogen on the surfaces.  相似文献   

6.
In this study, polymeric (MW 50 000) and oligomeric (MW 2000) poly (lactic acid) (PLA), both with and without end‐group deuterium exchange, were analysed using static secondary ion mass spectrometry (SSIMS) to investigate the contribution of end‐group‐derived secondary ions to the SSIMS spectra. By monitoring the SSIMS intensities between the non‐deuterated and deuterated PLA, it is evident that the only significant end‐group‐derived secondary ions are [nM + H]+ (n > 1) and C4H9O2+. The gentle‐SIMS (G‐SIMS) methodology was employed to establish that deuterated fragments were produced through low energy processes and were not the result of substantial rearrangements. It was noted that end‐group‐derived secondary ions had higher G‐SIMS intensities for oligomeric PLA than polymeric PLA, showing that these secondary ions are simple fragment products that are not the result of rearrangement or degraded product ions. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

7.
The accuracy of ultrashallow depth profiling was studied by secondary ion mass spectrometry (SIMS) and high‐resolution Rutherford backscattering spectroscopy (HRBS) to obtain reliable depth profiles of ultrathin gate dielectrics and ultrashallow dopant profiles, and to provide important information for the modeling and process control of advanced complimentary metal‐oxide semiconductor (CMOS) design. An ultrathin Si3N4/SiO2 stacked layer (2.5 nm) and ultrashallow arsenic implantation distributions (3 keV, 1 × 1015 cm?2) were used to explore the accuracy of near‐surface depth profiles measured by low‐energy O2+ and Cs+ bombardment (0.25 and 0.5 keV) at oblique incidence. The SIMS depth profiles were compared with those by HRBS. Comparison between HRBS and SIMS nitrogen profiles in the stacked layer suggested that SIMS depth profiling with O2+ at low energy (0.25 keV) and an impact angle of 78° provides accurate profiles. For the As+‐implanted Si, the HRBS depth profiles clearly showed redistribution in the near‐surface region. In contrast, those by the conventional SIMS measurement using Cs+ primary ions at oblique incidence were distorted at depths less than 5 nm. The distortion resulted from a long transient caused by the native oxide. To reduce the transient behavior and to obtain more accurate depth profiles in the near‐surface region, the use of O2+ primary ions was found to be effective, and 0.25 keV O2+ at normal incidence provided a more reliable result than Cs+ in the near‐surface region. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

8.
The effects of doping cobalt oxides with different amounts of ZrO2 and ThO2 (1.5–9 mol%) on the thermal stability of Co3O4 and the re-oxidation of CoO by O2 to Co3O4 were investigated. The techniques employed were DTA, with a controlled rate of heating and cooling, X-ray diffraction, and IR spectrometry.The results obtained by DTA revealed that the addition of both Th4+ and Zr4+ (up to 6 mol%) exerted no appreciable effect on the thermal stability of Co3O4. Increasing the amount of the dopant ions to 9% resulted in no further change in the thermal stability of Co3O4 in the case of Th4+, and an increase of 16% in case of Zr4+-doping. However, ThO2-doping of cobalt oxide was accompanied by an enhancement in the reactivity of CoO towards re-oxidation by O2 to Co3O4 to an extent proportional to the amount of dopant oxide.The X-ray investigation of ZrO2-doped cobalt oxides calcined in air at 1000°C revealed the presence of highly crystalline and stable zirconia in the cubic form. Such a stable phase could not be obtained at temperatures below 2370°C in the absence of stabilizing agents.X-ray and IR investigations of different solids showed the presence of free thoria and zirconia together with new thorium—cobalt and zirconium—cobalt compounds. However, the slow cooling of Zr-treated cobalt oxides from 1000°C to room temperature led to the decomposition of the newly formed compound. The d-spacings and absorption bands of the newly formed compounds were determined.  相似文献   

9.
A series of synthetic mixtures of thorium isotopes was prepared on a gravimetrical basis. The starting compounds consisted of natural thorium 232Th (99.99%) and highly enriched 230Th (99.8%). These materials were chemically purified and characterized for isotopic composition and chemical purity. Thorium dioxide (ThO2) was demonstrated to be a suitable compound for gravimetrical blending. The isotope amount ratios in the mixtures ranged from 10−2 to 3 × 10−6. These synthetic isotope mixtures are to our knowledge, the first ever prepared for thorium and may serve for calibration purposes.  相似文献   

10.
11.
《Mendeleev Communications》2023,33(1):135-137
The local environment of thorium in murataite ceramics (Al,Ca,Ti,Mn,Fe,Zr,Th)Ox and ThO2(001) crystalline film on Si(100) substrate as a reference was explored by X-ray absorption spectroscopy (XAS) for the first time. It was found that Th4+ is located in the center of a cube formed by 8 oxygen atoms [r(Th–O) = 2.37 ± 0.03 Å] in murataite ceramics and ThO2 film. The Th4+ second coordination sphere [r(Th–M) ≈ 3.5 Å] in murataite is represented by 3d metals: titanium, iron or manganese  相似文献   

12.
A recently developed atmospheric pressure ionization source, a distributed plasma ionization source (DPIS), was characterized and compared to commonly used atmospheric pressure ionization sources with both mass spectrometry (MS) and ion mobility spectrometry (IMS). The source consisted of two electrodes of different sizes separated by a thin dielectric. Application of a high RF voltage across the electrodes generated plasma in air yielding both positive and negative ions. These reactant ions subsequently ionized the analyte vapors. The reactant ions generated were similar to those created in a conventional point-to-plane corona discharge ion source. The positive reactant ions generated by the source were mass identified as being solvated protons of general formula (H2O)nH+ with (H2O)2H+ as the most abundant reactant ion. The negative reactant ions produced were mass identified primarily as CO3, NO3, NO2, O3 and O2 of various relative intensities. The predominant ion and relative ion ratios varied depending upon source construction and supporting gas flow rates. A few compounds including drugs, explosives and amines were selected to evaluate the new ionization source. The source was operated continuously for 3 months and although surface deterioration was observed visually, the source continued to produce ions at a rate similar that of the initial conditions.  相似文献   

13.
This present research aims to synthesize and investigate the adsorption potential of sugarcane bagasse (SCB) impregnated with 8 hydroxy quinolone 8-(HQ) and 1,10 phenethroline (phen) to prepare impregnated sugarcane bagasse (ISCB) for removal UVI and ThIV. The effects of the operating parameters, including pH of the solution, contact time, initial concentration, temperature, dose and interfering ions on the adsorption efficiency were investigated to identify an optimal condition. The characterization of SEM-EDX and FTIR analyses shows that ISCB has a porous structure and carbon-containing functional groups. The adsorption result revealed that ISCB removed 98 % for both UVI and ThIV. The result obtained fitted well for Langmuir isotherms model with 185.19 mg · g–1 and 250 mg · g–1 as theoretical capacity for UVI and ThIV respectively. The adsorption process followed the pseudo-second-order kinetic model. In conclusion, this study proved that ISCB has the potential to be used as an effective and low-cost adsorbent to remove UVI and ThIV. Finally we obtain products from thorium as ThO2 and uranium as Na2U2O7 from Abu Rushied leach liquor.  相似文献   

14.
The crystal chemistry of the valence stable Thorium (Th4+) shows in oxovanadates, ‐niobates, ‐molybdates, ‐tantalates etc. typical cationic property. It depends on the big size of the Th4+ ion in the order of r(Th4+) = 0.92 Å (C.N. = 6) up to r(Th4+) = 1.34 Å (C.N. = 12), comparable with the radii of alkaline and alkaline earth metals: r(Na+) = 1.02 Å (C.N. = 6) or r(K+) = 1.5 Å (C.N. = 8); r(Ca2+/Sr2+) = 1.1 Å/1.26 Å (C.N. = 8). There exists only one typical compound that may be of the oxothorate type with the composition NaK3Th2O6. Na+ and K+ can be declared to be components of the cationic part of the crystal structure. In contrary, thorium and oxygen are common components of the anionic part of the crystal structure. From the point of view of the shared polyhedra (exclusively octahedra), NaK3Th2O6 belongs to the thorium‐oxometallates too. The report on oxometallates of thorium shows compounds with one, two, four and five Th4+ atoms in combination with V5+, Nb5+, Ta5+ and Mo6+. W6+ is completely missing. Some of the Tantalates belong to the Jahnberg compounds, showing planar nets of corner shared pentagonal bipyramids. ThMO4 and cationic mixed compounds, Th1–xAxMO4, crystallize with the Scheelite (respectively Huttonite) structure and at least Th4+ is part of ordered and disordered perowskites showing more or less deviations from the cubic symmetry.  相似文献   

15.
This work reports a comparison of oligomer and fragment ion intensities resulting from primary ion bombardment with several primary ion sources (Bin+, C60+, and Cs+) at various energies in secondary ion mass spectrometry (SIMS). Although the use of polyatomic primary ions are of great interest due to increased secondary ion efficiency and yield, we demonstrate that monatomic primary ions result in increased oligomer ion yield for polymers prepared as submonolayer films on silver substrates. The enhancement of oligomer secondary ion yield with monatomic ions is evidence that monatomic primary ions have a shallower sampling depth than polyatomic ions, resulting from a collision cascade that is less energetic at the sample surface. The results are also consistent with a lower degree of fragmentation of the resultant secondary ions, which is observed when evaluating the fragmentation data and the spectral data.  相似文献   

16.
The rate constants for proton transfer from H3+ ions to N2, O2, and CO have been measured as function of hydrogen buffer gas partial pressure. The rate constant for proton transfer from H3+ to N2 shows a very large pressure dependence, increasing from 1.0 × 10?9 cm3/s at low H2 partial pressures to 1.7 × 10?9 cm3/s at high H2 partial pressures. The rate constants for proton transfer from H3+ to O2 and CO are constant with partial pressure of H2; giving values of 6.4 × 10?10 cm3/s and 1.7 × 10?9 cm3/s, respectively. The roles of excess vibrational energy in H3+ ions and of equilibrium between forward and back reaction are discussed. Back reaction is observed only for the reaction of H3+ ions with O2, and an equilibrium constant of K = 2.0 ± 0.4 at 298 K has been determined. From these data the proton affinity of O2 is deduced to be 0.47 ± 0.11 kcal/mole higher than that of H2.  相似文献   

17.
Ionization-fragmentation of uranium(IV) tetraborohydride, U(BH4)4, by He+ and by N+/N2+ yields, predominantly, U(BH5)+ and U(B2H8)+, respectively. Attachment of thermal electrons yields U(BH4)4? and ions of 1, 2, and 3 mass units less. Fluoride transfer with SF6?, BF4?, and UFn? (n = 5–7) and reactions with other small ions (O?, O2?, NO2?, F?, Cl?, O2+) are described.  相似文献   

18.
This paper describes how weakly bound adduct ions form when the precursor ions used in selected ion flow mass spectrometry, SIFT-MS, analyses, viz. H3O+, NO+ and O2+, associate with the major components of air and exhaled breath, N2, O2 and CO2. These adduct ions, which include H3O+N2, H3O+CO2, NO+CO2, O2+O2 and O2+CO2, are clearly seen when dry air containing 5% CO2 (typical of that in exhaled breath) is analysed using SIFT-MS. These adduct ions must not be misinterpreted as characteristic product ions of trace gases; if so, serious analytical errors can result. However, when exhaled breath is analysed these adduct ions are partly removed by ligand switching reactions with the abundant water molecules and the problems they represent are alleviated. But the small fractions of the adduct ions that remain in the SIFT-MS spectra, and especially when they are isobaric with genuine characteristic product ion of breath trace gases, can result in erroneous quantifications; such is the case for H3O+N2 interfering with breath ethanol analysis and H3O+CO2 with breath acetaldehyde analysis. However, these difficulties can be overcome when the isobaric adduct ions are properly recognised and excluded from the analyses; then these two important compounds can be properly quantified in breath. The presence of O2+CO2 in the product ion spectra interferes with the analysis of CS2 present at low levels in exhaled breath. It is likely that similar problems will occur as other trace compounds are detected in exhaled breath when consideration will have to be given to the possibility of overlapping between their characteristic product ions and ions produced by hitherto unknown reactions. Similar problems are evident in other systems; for example, H3O+CH4 adduct ions are observed in both SIFT-MS analyses of methane rich mixtures like biologically generated waste gases and in model planetary atmospheres.  相似文献   

19.
Round-robin characterization is reported on the sputter depth profiling of CrN/AlN multilayer thin-film coatings on nickel alloy by secondary ion mass spectrometry (SIMS) and glow-discharge optical emission spectrometry (GD-OES). It is demonstrated that a CAMECA SIMS 4550 Depth Profiler operated with 3 keV O2+ primary ions provides the best depth resolution and sensitivity. The key factor is sample rotation, which suppresses the negative influence of the surface topography (initial and ion-induced) on the depth profile characteristics.  相似文献   

20.
The title compound, [Th(C12H15O4)4]n, is the first homoleptic thorium–carboxylate coordination polymer. It has a one‐dimensional structure supported by the bidentate bridging coordination of the singly charged 3‐carboxyadamantane‐1‐carboxylate (HADC) anions. The metal ion is situated on a fourfold axis (site symmetry 4) and possesses a square‐antiprismatic ThO8 coordination, including four bonds to anionic carboxylate groups [Th—O = 2.359 (2) Å] and four to neutral carboxyl groups [Th—O = 2.426 (2) Å], while a strong hydrogen bond between these two kinds of O‐atom donor [O...O = 2.494 (3) Å] affords planar pseudo‐chelated Th{CO2...HO2C} cycles. This combination of coordination and hydrogen bonding is responsible for the generation of quadruple helical strands of HADC ligands, which are wrapped around a linear chain of ThIV ions [Th...Th = 7.5240 (4) Å] defining the helical axis.  相似文献   

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