Surface analysis depth profiling

SIMS No mm or xm sample Flat surface for analysis under vacuum Surface analysis, depth profile Some metre in depth Some ppm... 

Interface Science. The interface of two materials can be probed using several techniques, including some of the techniques used for surface analysis. Depth profiling is a method by which information is gained from within the sample. If the interface in... 

SALI Surlace Analysis by Laser Ionization Surface e-beam, ion-beam, or laser for sputtering Sputtered atoms ioni by laser then mass analyzed 0.1-0.5 nm ip to 3 in in milling mode 60 nm Surface analysis depth profiling 7... 

Besides the conventional Grimm-type dc source, which has dominated the GD-OES scene for approximately 30 years, other discharge sources are well known. Among those are various boosted sources which use either an additional electrode to achieve a secondary discharge, or a magnetic field or microwave power to enhance the efficiency of excitation, and thus analytical capability none of these sources has, however, yet been applied to surface or depth-profile analysis. 

The introduction of rfpowered sources has extended the capability of GD-OES to non-conductors, and several rf sources of different design have become commercially available. This is of the greatest importance for surface and depth-profile analysis, because there exists a multitude of technically and industrially important non-conductive coating materials (e. g. painted coatings and glasses) which are extremely difficult to analyze by any other technique. 

Inorganic mass spectrometry requires the development of suitable reference materials, such as matrix matched standard reference materials for trace, surface (including depth profiling and microlocal) analysis and/or the creation of matrix independent calibration procedures. The development of species specific standards will be intensified for speciation studies in the future. 

Auger electron spectroscopy (AES) is particularly suited for surface analysis (depth 0.5-1 nm). AES depth profile analysis was employed to determine the thickness and composition of surface reaction layers formed under test conditions in the Reichert wear apparatus in the presence of four different ZDDPs additives at different applied loads (Schumacher et al., 1980). Using elemental sensitivity factors the concentration of the four elements (S, P, O, C) was determined at three locations corresponding to a depth of 1.8, 4.3, and 17 nm. No significant correlation between wear behavior and carbon or oxygen content of the reaction layer was observed. A steady state sulfur concentration is reached after a very short friction path. Contrary to the behavior of sulfur, phosphorus concentration in the presence of ZDDPs increases steadily with friction path, and no plateau value is reached. 

X-ray photoelectron spectroscopic(XPS) analysis with argon-etching gives surface and depth profile of catalyst composition[20]. Figure 2 shows enriched Te-content at surface of Te/Mo=... 

Dynamic SiiViS Dynamic Secondary ion iviass Spectroscopy Surface Ion beam (1-20 keV) Secondary ions analysis with mass spectrometer 2 nm-1 pm (or deeper iorr milling) 0.60 nm Elemental and isotopic analysis depth profile (all elements) deleclion limils ppb-ppm 4... 

The following sections will deal first with the physical effects involved in postionization, then with the respective instrumentation, and finally with the quantification schemes in surface and depth profile analysis with SNMS. A critical comparison of the different SNMS techniques will be addressed where appropriate. 

SIMS and SNMS represent the most powerful mass spectrometric techniques for surface and depth profile analysis, allowing the determination of element distributions on solid sample surfaces at trace and ultratrace element contents [2,3,26]. 

Microthermal analysis has been used in surface and depth profiling studies of PP [51,52], multi-block copolymers [53], polytetrafluoroethylene/silicone blends [14],PEG/polylactic acid blends [55], and PS/polyvinyl methyl ether blends [56]. See also Section 3.12. 

Some solid materials are very intractable to analysis by standard methods and cannot be easily vaporized or dissolved in common solvents. Glass, bone, dried paint, and archaeological samples are common examples. These materials would now be examined by laser ablation, a technique that produces an aerosol of particulate matter. The laser can be used in its defocused mode for surface profiling or in its focused mode for depth profiling. Interestingly, lasers can be used to vaporize even thermally labile materials through use of the matrix-assisted laser desorption ionization (MALDI) method variant. 

A depth profile is a record of the variation of a property (such as composition) as a function of depth. Some of the techniques in this volume have essentially no intrinsic depth profiling capabilities the signal is representative of the material integrated over a fixed probing depth. Most, however, can vary the depth probed by varying the condition of analysis, or by removing the surface, layer by layer, while collecting data. 

Sputtered Neutral Mass Spectrometry (SNMS) is the mass spectrometric analysis of sputtered atoms ejected from a solid surface by energetic ion bombardment. The sputtered atoms are ionized for mass spectrometric analysis by a mechanism separate from the sputtering atomization. As such, SNMS is complementary to Secondary Ion Mass Spectrometry (SIMS), which is the mass spectrometric analysis of sputtered ions, as distinct from sputtered atoms. The forte of SNMS analysis, compared to SIMS, is the accurate measurement of concentration depth profiles through chemically complex thin-film structures, including interfaces, with excellent depth resolution and to trace concentration levels. Genetically both SALI and GDMS are specific examples of SNMS. In this article we concentrate on post ionization only by electron impact. 

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-... 

The results shown in Figure 6 above are an example of this mode of analysis, but include additional information on the chemical states of the Si. The third most frequently used mode of analysis is the Auger mapping mode, in which an Auger peak of a particular element is monitored while the primary electron beam is raster scanned over an area. This mode determines the spatial distribution, across the surface, of the element of interest, rather than in depth, as depth profiling does. Of course, the second and third modes can be combined to produce a three-dimensional spatial distribution of the element. The fourth operational mode is just a subset of the third mode a line scan of the primary beam is done across a region of interest, instead of rastering over an area. 

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