AES analysis

The Nb 7 d spectra (not shown) contained two maxima at ca. 203 and 206 eV, an energy separation characteristic of the 5/2-3/2 spin-orbit splitting. The 3tf line. shape was always complex because of the pre.sence of various Nb oxides, probably NbO and NbiO according to the results reported by Grundner and Halbritter on the oxidation of Nb metal [50], 

The evolution with depth of the Pb 4/7/2 line shape was quite different for the two junctions, as evident from Figs. 4 and 5. That from the Nb/Pb device was dominated by the component from the surface oxide down to the depth reached after the third sputtering sequence, i.e., at the insulant barrier. PbO was still detected subsequently, but with an ever-decreasing content relative to that of Pb metal. In contrast, Pb metal was easily detectable at the surface of the Nb/(Pb-ln) device, and its level increased at the expen,se of PbO up to the second sputtering sequence, when the Pb 4/7/2 spectrum became characteristic of metallic Pb. At the insulator barrier, however, PbO species appeared again (third to fifth sequence). 

The beneficial protective effect of In can be inferred from the presence of Pb metal at the surface and from the absence of PbO in the internal regions (Fig. 5). As di.scussed in Chapter 19, these results are similar to those obtained in a comparison of surface compositional measurements on pure Pb and on a Pb-Sn alloy. In that case, too, it was demonstrated clearly that tin played a sacrincial role through preferential formation of SnOj, and that the process limited significantly the extensive oxidation of lead. 

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The purpose of the study was the development of multi-elemental teehnique for induetively eoupled plasma atomie-emission speetrometry (ICP AES) analysis of blood semm. 

AES analysis is done in one of four modes of analysis. The simplest, most direct, and most often used mode of operation of an Auger spectrometer is the point analysis mode, in which the primary electron beam is positioned on the area of interest on the sample and an Auger survey spectrum is taken. The next most often used mode of analysis is the depth profiling mode. The additional feature in this mode is that an ion beam is directed onto the same area that is being Auger analyzed. The ion beam sputters material off the surface so that the analysis measures the variation, in depth, of the composition of the new surfaces, which are being continu-... 

A. J. Bevolo, J. D. Verhoeven, and M. Noack. Surf. Set. 134,499, 1983. Comparison ofVEELS and AES analysis of the early stages of the oxidation of solid and liquid tin. Illustrates one of the main uses for REELS. 

If a sample of polycrystalline material is rotated during the sputtering process, the individual grains will be sputtered from multiple directions and nonuniform removal of material can be prevented. This technique has been successfully used in AES analysis to characterize several materials, including metal films. Figure 9 indicates the improvement in depth resolution obtained in an AES profile of five cycles of nickel and chromium layers on silicon. Each layer is about 50 nm thick, except for a thinner nickel layer at the surface, and the total structure thickness is about 0.5 pm. There can be a problem if the surface is rough and the analysis area is small (less than 0.1-pm diameter), as is typical for AES. In this case the area of interest can rotate on and off of a specific feature and the profile will be jagged. 

M diethyltriaminepentraacetate (DTPA), and 0.50 M NH4OH. Distribution ratios measured by ICP/AES analysis were estimated to have a standard deviation of 20%. 

Fig. 4. (a) Ni nanociystals formed on HfOj after sputtering followed by annealing and (b) AES analysis of the elemental composition of the islands and matrix suggested well separated metal nanocrystals. 

Figure 1 shows two reactor configurations we have used to measure reaction rates on clean surfaces. In Figure 1(a) is shown a high pressure cell inside the UHV system ( ) with the sample mounted on a bellows so it can be moved between the reaction cell and the position used for AES analysis. In Figure 1(h) is shown a reaction cell outside the analysis system with the sample translated between heating leads in the reactor and in the UHV analysis system ( ). 

Figure 5.32. Illustrating common configurations of elements that may be quantified by AES analysis (a) homogeneous (b) large, well-defined structures varying laterally and with depth (c) small, well-defined structures varying laterally and with depth, (d) monolayer segregants and absorbed layers (e) layered composition gradients and (f) a catalyst promoter on a layered support. (After Seah 1986,...

The chemical analysis by ICP-AES showed that the determined M2+/M3+ molar ratio in Zn2Al (Table 1) was very close to the nominal ratio of the synthesis mixture, and is supporting the XRD results. For Zn2Ga, the Zn/Ga ratio was slightly higher than 2 due to the presence of an excess of ZnO, also evidenced by XRD. ICP-AES analysis of the Rh exchanged LDH indicated a similar Rh content in the two samples (Table 1). The TPPTS Rh (wt%) ratio was found to be a value of 2.83, in agreement with the structure of the expected complex [9c]. 

Only a slight decrease in the conversion was observed during the recycling. No leaching of the immobilized rhodium complex occurred as indicated by ICP-AES analysis of the mother liquor. 

The concept of continuous flow SILP hydroformylation was also tested in the biphasic, liquid-liquid hydroformylation of 1-octene using the Rh-norbos catalyst system [78], TOFs of 44 h"1 were achieved after 3-4 h with no sign of deactivation at prolonged reaction times. At steady-state conditions an n/iso ratio of 2.6 was obtained. No leaching of rhodium metal could be detected by ICP-AES analysis of product samples at least after these short reaction times. 

Once the pure mineral powders characterized, 3 mixtures were manually prepared and named ML1, ML2 and ML3. They contain each of the 8 minerals in different proportions reproducing 3 mine tailings falling in the uncertainty zone of the static test used. The 3 synthetic tailings were characterized with the same techniques as for the pure minerals. Cp and Sp weight fractions were evaluated from their chemical element tracers (respectively Cu and Zn) obtained from ICP-AES analysis. Qz, Dol, and Sid samples are considered pure and their percentages in the mixtures are not corrected. Table 1 presents the fraction of each mineral in the three mixtures before and after correction taking into consideration the contamination of Po sample by pyrite and calcite, as previously determined. The corrected mineral proportions are used for calculation of the static test parameters based on... 

As a by-product of AES analysis, ASs were separated by LC-EP-Ci8 [52], combined with ion spray (ESI(—)) ionisation and then this method was used for monitoring individual species of the ASs (CraH2n+1-0-SOs) and AESs by ESI-LC-MS. In addition, RP-C2 material had been applied for SPE of the pollutants prior to MS analysis. 

Au and AuPt nanoparticles were assembled on carbon black (XR-72C) or silica powders with a controlled weight ratio of the metals (Au or AuPt) vs. the support materials. The actual loading was determined by thermogravimetric analysis (TGA) and DCP-AES analysis. 

The nanostructured bimetallic catalysts were characterized using several techniques, and some of the main results are summarized in this section. We first describe the size and composition of the AuPt nanoparticles determined from TEM and DCP-AES analysis. This description is followed by discussion of the phase properties based on XRD results. We further discuss the FTIR provbing of CO adsorption on the bimetallic nanoparticle catalysts. 

ICP-AES was validated for the simultaneous determination of Al, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Se, Sr and Zn in human serum in a clinical laboratory. The samples underwent digestion and yttrium was used as an internal standard. The LOD were as follows 0.002-0.003 (xM for Ba, Cd, Mn and Sr 0.014-0.07 (xM for Be, Co, Cr, Cu, Fe, Li, Ni, Pb and Zn and 0.2-0.9 (xM for Al, B and Se. The concentrations of Al, Be and Co in human serum were found to be above the LOD, while those of Cd, Cr, Ni and Pb were below the LOQ however, in case of acute intoxication with the latter elements the method is valid . Matrix effects were evaluated for ICP-AES analysis using solution nebulization and laser ablation (LA) techniques. The main matrix-related interferences stem from elements with a low second ionization potential however, these are drastically reduced when pure He is used as carrier gas. This points to Ar (the usual carrier) participation in the interference mechanism, probably by interacting with doubly charged species. ... 

Iron carbonyls may be identified by electron diffraction and x-ray analysis. Also, its solutions in appropriate organic solvents, such as ether, methanol, or acetone may be analyzed by GC/MS. The characteristic mass spectra should indicate the molecular ions corresponding to the carbonyl as well as the mass spectra of CO and Fe(CO)n, where n is the number of CO units in the fragmented mass ions. Flame- or furnace-AA or ICP/AES analysis may be apphed on the nitric acid extract of the compound(s) after appropriate dilution to determine the concentration of iron (See Iron). 

The complexes were prepared from [CODRhCl]2 and 1.1 equiv of chiral diphosphine in dichloromethane as solvent. The chiral complex was added to a suspension of the support in dichloromethane. After being stirred for 24 h, the solid was filtered, washed with dichloromethane until the solvent showed no color, and afterward dried at room temperature for 16 h. In order to remove the excess of Rh complex not fixed to the solid carrier, the catalysts were extracted with methanol in a Soxhlet apparatus under reflux for 24h (Scheme 2.1.6.1). Both ICP-AES analysis and FTIR spectra of the remaining solvent indicated no content of homogeneous complex. The resulting catalysts had a pale yellow color similar to that of the homogeneous complex. 

A special case is the test of immobilization of rhodium-diphosphine complexes on all-silica materials. After the first immobilization step in dichloromethane, the solid material had a yellow color and a Rh content of 0.07 mmol g was found. After the extraction with methanol, the entire amount of organometallic complex was washed out and the final material had again the original white color. No rhodium was detected in ICP-AES analysis of this sample. However, in the case of aluminum-containing materials the orange color obtained after the immobilization of the rhodium complexes in dichloromethane is clearly maintained even after extraction in methanol. 

Determination of Mg in the hard tissues (shell and pearl) of shellfish by the ICP-AES method involves dissolution of the sample by hot concentrated nitric acid, hydrochloric acid and perchloric acid. However, the large excess of Ca in the matrix strongly interferes with the end analysis and causes damage to the torch. After adjusting the pH to 4.5, the Mg ions were extracted by a 0.01 M solution of 3-methyl-l-phenyl-4-trifluoroacetylpyrazol-5-one (16) in dibutyl ether and the ICP-AES analysis was carried out by direct injection of the organic solution. ... 

Figure 24.1 NEXAFS and AES analysis of VC/V(110). Open circles NEXAFS uptake curve obtained by measuring the fluorescence-yield of carbon K-edge feature at 285.5 eV following the formation of carbide on V(110) at 600 K. Closed circles the carbon/vanadium atomic ratios as a function of carbide formation as derived from the AES C(KLL)/V(LMM) peak-to-...

Lewis and coworkers have also made significant contributions to the understanding of the MCS reaction via the use of surface studies72. XPS and AES analysis of catalytically active surfaces showed that zinc causes a restructuring of the Cu3Si surface. Additionally, zinc enrichment is enhanced by the addition of SnCLt. Lead is a well known poison for the direct reaction and the Lewis group found that lead suppressed enrichment of the Cu3Si surface in zinc and silicon. 

In NiV intermetallics, Ni has been identified as providing the active sites, and it has been found that the as-prepared materials are less active because they are partially passivated by surface oxides. A treatment with HF greatly improves the activity, which is mainly related to the formation of a surface porous layer enriched with Ni as proven by AES analysis (Fig. 31). However, when NiV and Raney Ni are compared, for both the activity has been found to vary proportionally to the surface roughness factor, but the specific activity is much higher for NiV [542]. This indicates that synergetic effects are real in this case this recalls the observations made in the cases of Ni—Mo and Ni—Mo-Cd solid solutions [141, 518]. 

Sterile trace element free 100 ml Nalgene bottles (for ICP-MS and ICP-AES analysis)... 

Results. AES analysis of impact fracture surfaces on nickel showed considerable spread in sulfur composition at grain boundaries as shown in Fig. 2. The composition varied from approximately 0.04 to 0.20 monolayers on the sample heated to 1100°C for one hour and 0.15 to 0.25 monolayers on a sample that had received additional heating at 600°C for 240 hours. The additional heat treatment shifted the average grain boundary composition by nearly 0.1 monolayer of coverage. 

A simultaneous ICP-AES is the instrument preferred by the laboratories because it provides a fast and sufficiently sensitive analysis of multiple elements. Mercury is the only exception, as the high detection limit of the ICP-AES analysis for mercury does not meet the regulatory requirements. That is why mercury is analyzed with a much more sensitive CVAA technique. 

ICP-AES analysis is susceptible to spectral and non-spectral interferences spectral interferences constitute the greatest limitation of this otherwise sensitive and practical technique. 

The following non-spectral (physical and chemical) interferences from sample matrix are often observed in the ICP-AES analysis of environmental matrices ... 

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