For Depth Profiling Studies

Depth profiling studies of ultra shallow implanted P using NRA has been made by Kobayashi and Gibson (1999) in the energy range of 5-80 keV using P((x, p) Si reaction. 

Animals are dosed with small quantity of water enriched with the stable isotope and a blood sample is taken some hours later when isotopic equilibrium ( 0 0 99.76% 0.04% 0.2%) is reached. The animals 

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Confocal Raman microscopy was used to study the distribution and redistribution (by leaching) of the fungicide Fluorfolpet FF (5%) and DOP (10-30 wt.%) in PVC films [559]. The technique was also used for depth profiling studies of small surfactant molecules (sodium dodecyl sulfate, SDS) and sulfate anions (804 ) in dry BuA/AA latex films [560]. Other techniques such as ATR-FTIR and step-scan PAS have extensively been used for the same purpose, but have some limitations in the... 

From this table, it can be seen that by employing a range of crystals of different geometries and refractive indices, the depth of penetration can be varied over a wide range and so the ATR technique can be used for depth profile studies. 

It can be seen from the above discussion that the saturation effects may be important in the appearance of the FT-IR PA spectra. From the theoretical point of view, one can enhance the PA signal by employing lower modulation frequencies (lower mirror velocities in the case of FT-IR instruments). And, one can do a depth-profile study of the sample surface by varying the mirror velocities. It must be remembered, however, that when very low modulation frequencies are employed, it may be difficult to acoustically seal the PA cell against ambient noise futhermore, the saturation effects may become severe. For depth profiling studies, it must be remembered that this depth in general will vary as6o- -2or... 

This article discusses why one would choose nonresonant multiphoton ionization for mass spectrometry of solid surfaces. Examples are given for depth profiling by this method along with thermal desorption studies. 

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. 

Ion beams are often utilized to prepare clean surfaces for PES studies or for depth profiling through a sample. This causes problems in polymer studies as the surface can be chemically degraded as has been demonstrated in the case of polyimide (19,20). This effect, however, has been used to increase metal/polymer adhesion, while the exact mechanism (chemical, mechanical) for the improved adhesion for the metals to polyimide is not yet completely understood (21,22). 

A combined LEISS-AES-EC study was earlier undertaken at crystalline PtsCo and PtsNi alloy surfaces. It was reported that, when PtsCo and PtsNi were annealed at 1000 K, only Pt atoms existed on the outermost layer the latter was referred to as a Pt skin. This particular observation is not in agreement with the result here that Co actually co-exists with Pt at the outermost layer. Interestingly, when the PtsCo surface in the earlier study was lightly sputtered, approximately 25% of the sputtered material was Co this result suggests that Co is in fact present at the topmost layer. Why a discrepancy exists between the LEISS and depth-profile studies is unclear. But, for the difference between the present and previous LEISS work, the possibility exists that the interfacial be-... 

The variables that influence performance in GD sampling can be classified according to whether they are shared by the source and detector or pertain exclusively to one or the other. The optimum value for each variable depends on the particular aim of the work at hand (e g. quantitation in homogeneous samples, surface and depth profiling studies in layered samples). 

Currently available software enables the accumulation of spectra from an arbitrary number of laser shots with an arbitrary number of successive repetitions. This mode of operation is specially suitable for depth profile analysis. By way of example, in order to determine two components in a depth profiling study, a series of pulses are accumulated by maintaining a constant laser fluence. The experimentally measured intensities of the lines selected for the two elements are normalized to their maximum values to account for the difference in oscillator strength of the lines. Such values are then normalized to the sum of the intensities of both elements. Normalization to the combined intensities is equivalent to normalization to the ablated mass. This procedure is unsuitable for the lower layers of a sandwich close to the substrate, for which normalization should also include the line intensity for the substrate element. 

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