Microprobe technique

SSMS can be classified among the milliprobe techniques (Figure 8.3), i.e. it is a unique link between microprobe techniques and macroanalytical methods that are characterised by poor lateral and in-depth resolutions (as in OES), or that have no lateral resolution whatsoever (as in NAA). Also, the achievable precision and accuracy are poor, because of the irreproducible behaviour of the r.f. spark. Whereas analysis of metals, semiconductors and minerals is relatively simple and the procedures have become standardised, the analysis of nonconducting materials is more complex and generally requires addition of a conducting powder (e.g. graphite) to the sample [359]. Detection limits are affected by the dilution, and trace contamination from the added components is possible. These problems can be overcome by the use of lasers [360]. Coupled with isotope dilution, a precision of 5% can be attained for SSMS. 

Analytical studies, using scanning electron microscopy and electron microprobe techniques (see Textbox 10), revealed that the mixture used for making this particular type of ceramic material consists mainly of clay, comminuted... 

The progress was caused by the development of completely new methods, techniques, and principles (e.g. microprobe techniques) as well as the introduction of new system components into common instruments (e.g. flash... 

Bakraji, E. H., Othman, I., Sarhil, A., and Al-Somel, N. (2002). Application of instrumental neutron activation analysis and multivariate statistical methods to archaeological Syrian ceramics. Journal of Trace and Microprobe Techniques 20 57-68. 

Pillay, A. E. and Punyadeera, C. (2001). An enhanced procedure for the rapid digestion of high silicate archeological specimens followed by ICP-MS determination of traces of rare earth elements (REEs). Journal of Trace and Microprobe Techniques 19 225-241. 

Reiche, I., Yignaud, C., Favre-Quattropani, L., and Menu, M. (2002b). Fluorine analysis in biogenic and geological apatite by analytical transmission electron microscopy and nuclear reaction analysis. Journal of Trace and Microprobe Techniques 20 211-231. 

Other meteorite classes like C2, CO and ordinary chondrites contain much smaller inclusions less than 1 mm (MacPherson et al. 1988) and require ion microprobe techniques to evaluate the isotopic compositions. On the least metamorphosed side. Cl have very few inclusions or oxide grains, but are the carrier of the greatest amounts of stellar nanodiamond and other carbides (Anders and Zirmer 1993). As will be shown for Cr anomalies in carbonaceous chondrites, the survival of the mineral carriers of the anomalies also depends on the metamorphic grade of the meteorites. Nevertheless, isotopic anomalies have also been formd in higher metamorphic grade from other classes, especially in the reduced enstatite chondrites. 

The amount and uniformity of the solid state reaction of halogen with TTF was probed by the electron microprobe technique. In this analytical method, low energy electron irradiation of a sample provides X-ray core level emissions, characteristic of the element and its relative concentration. Our initial analyses indicated a dramatic dependence of the halogen concentration with the energy of the electron beam. To probe this phenomenon further,... 

The dentin-adhesive interface has been studied using a Raman microprobe technique [199], which shows the formation of resin-reinforced dentin and the penetration of resin into dentin substrate to a depth of 5-6 microns. Further study of the interface showed that only small molecules such as MMA, 4-MET (hydrolyzed 4-META) or oligomers infiltrated the dentin, and that all of the resin in the dentin originated from the monomer solution [200]. SEM and TEM studies of the ultrastructure of the resin-dentin interdiffusion zone showed a 2 micron zone with closely packed collagen fibrils running parallel to the interface [201]. 

By the late 1980s ion microprobe techniques had become sufficiently refined to search for 26A1 in chondrules, the dominant component of chondrites. A few studies showed positive results, such as a feldspar-bearing clast chondrule from Semarkona that gave an initial ratio of 7.7 x 10 fi (Hutcheon and Hutchison, 1989). However many did not. Eventually, it was shown that feldspar and glass in chondrules are easily affected by parent body... 

Miadokova, E., Duhova, V., Rezna, M., Kralikova, A., Sucha, V. and Vlcek, D. (1998) Genotoxicological research on the waste mine drainage water, Journal of Trace and Microprobe Techniques 16, 453-... 

SIMS (61,64,86), microscopy (65), XPS (56), electron microprobe techniques (14,66), electron paramagnetic resonance (EPR) (67) and luminescence experiments (68) have been successfully employed to probe and study V mobility and reactivity on a catalyst surface. TEM, STEM and energy dispersive X-ray emission (EDX) measurements have indicated that V interaction with REY-crystals induced vanadate clusters formation (65). Vanadium was also found capable of reacting with rare-earths outside the zeolite cavities to form LaVQ4... 

In general, microprobe analysis methods have been considered semiquantitative, but EPMA has been promising for quantitative studies. With further improvement and investigation, these microprobe techniques will be useful for the characterization of surface and bulkparticle properties. 

Modern surface analytical tools make it possible to probe the physical structure as well as the chemical composition and reactivity of interfacial supramolecular assemblies with unprecedented precision and sensitivity. Therefore, Chapter 3 discusses the modern instrumental techniques used to probe the structure and reactivity of interfacial supramolecular assemblies. The discussion here is focused on techniques traditionally applied to the interrogation of interfaces, such as electrochemistry and scanning electron microscopy, as well as various microprobe techniques. In addition, some less common techniques, which will make an increasing contribution to supramolecular interfacial chemistry over the coming years, are considered. 

The nature of solid, liquid or gaseous inclusions that may be found within transparent inorganic glass or crystalline materials can be determined by Raman microprobe techniques without breaking up the sample (39). Other analytical techniques, such as mass spectroscopy or electron microscopy, that may be used to obtain such information require destruction of the original sample. This capability of the microprobe is useful if one wants to analyze inclusions in a material before and after a sample treatment. The only limitation is that the position of the inclusion in the material must be located within the working distance of the objective lens in the microscope (39). 

Four flat, disc-shaped laminar flow flames were probed and analyzed using standard microprobing techniques. The flames were composed primarily of CO, H2, 02> and Ar with small amounts of CH4 or natural gas added to simulate intermediate Btu gas mixtures. Gas compositions used in the probings are presented in Table 1. Flames A and B contained excess air, air/fuel equivalence ratio = 1.13 Flames C and D were slightly fuel rich, air/fuel equivalence ratio = 0.93. Each of the mixtures had a CO/H2/X (X = methane or natural gas) mole ratio of 1/1/0.22. 

Some of these methods (x-ray fluorescence spectrometry, neutron activation analysis) can directly be applied to the analysis of rocks and soils. No dissolution is needed, and therefore they are called dry methods. The chemical composition of rock and soil samples can directly be analyzed by microprobe techniques (e.g., scanning electron microscopy). The resolution of these methods is about 1 pm, so the composition of individual particles can be investigated separately. 

From the areas of this Green River shale sample that were examined in detail using the slow rastering microprobe technique, we have chosen three for discussion. Area A was a dark band located near the 6000-/xm position in Figure 1. Area B was in the wide, lighter colored area located at 13,000 fim, and area G included a black, organic strip at 16,000... 

The Devonian shale sample generally had a darker appearance with fewer and less distinct bands than the Green River shale sample, and the organic matter appeared to be more evenly distributed over the 2.5-cm sample. Several areas of this sample were examined using the slow rastering microprobe techniques to determine the elemental distribution in this material. The observations made in two of the areas are presented below. 

Sharp Z. D. (1992) In situ laser microprobe techniques for stable isotope analysis. Chem. Geol. 101, 3-19. 

---