Mineral depth profiles

Today dynamic SIMS is a standard technique for measurement of trace elements in semiconductors, high performance materials, coatings, and minerals. The main advantages of the method are excellent sensitivity (detection limit below 1 pmol mol ) for all elements, the isotopic sensitivity, the inherent possibility of measuring depth profiles, and the capability of fast direct imaging and 3D species distribution. 

Figure 16. Depth profiles from three ODP Sites, showing Li isotopic composition variations in pore waters (open symbols) and associated sediments (filled symbols), (a) Site 918, Irminger Basin, north Atlantic (Zhang et al. 1998) (b) Site 1038, Escanaba Trough, northeastern Pacific (James et al. 1999) (c) site 1039, Middle American Trench off of Costa Rica (Chan and Kastner 2000). The average composition of seawater is noted on each profile with dashed line (note different scales). Whereas sediments have relatively monotonous compositions, pore waters have compositions reflecting different origins and processes in each site. Interpretations of the data are summarized in the text under, Marine pore fluid-mineral processes. ...

The sum of these observations suggests that metal phosphate crystalline mineral phases, some of which are solid solutions, are present in the samples. These phases may be discrete or surface precipitates. Some work on scmbber residues using depth profiling techniques with secondary ion mass spectrometry (SIMS) suggest that surface... 

XPS, SAM, SIMS Analyses. For reaction times < 5 days, or [Cs+] < 10 4 mol dm 3, XPS results showed about 10 atomic % Cs to be present on the surface of the mineral samples. Depth profiling using SIMS indicated that in these cases, the sorbed Cs was present for only the first 200 nm. 

SIMS has become one of the most important tools for the characterization of experimental products because of its minimal sample requirements, high spatial resolution, excellent sensitivity, and unsurpassed ability for depth-profile measurements. Most of the experimental work can be split into two different areas. The first consists of studies examining diffusion rates of different elements in minerals or melts under a variety of pressure, temperature, and fluid conditions, typically by using an isotopically enriched tracer. These analyses are done either by cutting a surface parallel to the diffusion direction and taking a traverse of spot analyses (for conditions in which profiles in the tens to hundreds of micrometers are expected) or by depth-profiling in from the mineral surface to depths of as much as 5-10 micrometers. In the latter mode, depth resolution on the tens of nanometer scale is possible (see Chapter 4). The second area is focused on determining partition coefficients for trace elements between different minerals and fluids/melts at specific temperatures, pressures, and fluid conditions, to provide the data needed to interpret trace element contents measured in natural minerals. This type of analysis typically involves spot analysis of mineral run products. 

The chemical state of aluminum on the surface has a multitude of possible configuration designations. The state in the hydroxylated outer layer corresponds to various mineral phases such as AIO(OH) (boehmite), Al(OH)3, having a modified Auger parameter of 1460.6 on the acetone-cleaned surface and 1461.4 on both the (Aik) and (Dox) surfaces. When capped with a plasma polymer, depth profiles show that the state of the aluminum is seen to be consistent with the many oxides, as well as mixed states with plasma film components. 

As in most parts of today s deep ocean the concentrations of Ca and of CO are nearly constant with water depth, profiles of CaCOs content with depth reflect mainly the increase in the solubility of the mineral calcite with pressure (see Figure 2). This increase occurs because the volume occupied by the Ca and ions... 

Fig. 3. Mean mineral density profiles of two artificial caries lesions. Mineralisation, as a percentage of sound enamel, assumed to be 87% mineral by volume, is expressed as a function of depth into the lesion. The two mineral distributions are clearly different but the amount of mineral loss is almost identical in each case. In the text, the terms shallow and deep refer to lesion depth, whereas the terms small lesion and Targe lesion refer to amount of mineral loss, regardless of depth. The heavy line represents a lesion with a high R parameter and the lighter line, a lesion with a lower R parameter (see 4.6).

FIGURE 3.1 Density-depth profile for the top 1,000 km of the Earth s mantle showing the main mineral phases present in the different layers. (Depth density data from Montagner. Anderson, 1989.)... 

Detailed studies of mantle xenoliths combining age determinations with the results of mineral barometry allow age-depth profiles to be constructed for some kimberlite pipes (Fig. 3.11). The results of such studies do not show any obvious age-depth relationship which is puzzling, maybe reflecting melt infiltration... 

Saturation indices were determined with the PHREEQC model for the core which pore water concentration profiles were previously shown in Chapter 3, Figure 3.1. Here, our attention was drawn to the supersaturation of several manganese minerals in various depths, and thus in differing redox environments. Figure 15.1 shows the depth profiles for the saturation indices of the minerals... 

NRA technique has been used to characterize the obsidian samples from different mineral sites in Mexico by Murillo et al. (1998) who have determined the oxygen concentration by means of the 0(d, p) 0 reaction. To determine the structure and composition of the patina through the depth profiles of the constituent elements like C, N, O, the (d, p) nuclear reactions have been employed using the external beam NRA measurements on copper alloys of archaelogical significance with 3MeV protons and 2MeV deuterons by loannidou et al. (2000). 

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