SSIMS surface specificity

Compared with XPS and AES, the higher surface specificity of SSIMS (1-2 mono-layers compared with 2-8 monolayers) can be useful for more precise determination of the chemistry of an outer surface. Although from details of the 01s spectrum, XPS could give the information that OH and oxide were present on a surface, and from the Cls spectrum that hydrocarbons and carbides were present, only SSIMS could be used to identify the particular hydroxide or hydrocarbons. In the growth of oxide films for different purposes (e.g. passivation or anodization), such information is valuable, because it provides a guide to the quality of the film and the nature of the growth process. 

In general. SSIMS has not been used for quantification of surface composition because of all the uncertainties described above. Its application has been more qualitative in nature, with emphasis on its advantages of high surface specificity, very high sensitivity for certain elements, and multiplicity of chemical information. Increasingly, it... 

Although treated here as one of the major surface analytical techniques, ISS, like SSIMS. is used much less extensively than XPS or AES. Again, like SSIMS, it is often used in conjunction with other techniques and is valuable as a complement to the others for its two advantages of high surface specificity and ease of quantification,... 

Surface mass spectrometry (SSIMS and SNMS) is a very powerful tool for the chemical characterization of surfaces. It is able to identify elements and molecules present, it is sensitive down to the ppb and fmol levels, it is very surface specific (information depth = the outermost monolayer) and allows the determination of the lateral distributions of elements and molecules with sub- im resolution. Furthermore it can be applied to almost any material in general without any special preparation (i.e., as-received). It therefore should be the method of... 

Treatment of polymer surfaces to improve their wetting, water repulsion, and adhesive properties is now a standard procedure. The treatment is designed to change the chemistry of the outermost groups in the polymer chain without affecting bulk polymer properties. Any study of the effects of treatment therefore requires a technique that is specific mostly to the outer atomic layers this is why SSIMS is extensively used in this area. 

Fig. 18. From a sample of 0.12 g CuCI monolayer dispersed on 1 g -y-Al203 of a specific surface (343 m2/g) SSIMS signal is found to decline exponentially with time. Ar+ ion beam 1 keV and 0.6 nA.

The description of XPS and SSIMS will concentrate on the underlying physical processes that generate surface chemical data. Information on the design of instruments and specific details of operating procedures and conditions have been provided by a number of excellent books and review articles [13-18],... 

RBS has been in use since the 1960s for bulk materials analysis, and increasingly since the 1970s for thin-film analysis, particularly in the semiconductor field. The overall number and range of applications are enormous, but those dealing specifically with surface problems are less numerous. Nevertheless RBS ranks along with SSIMS and ISS as one of the major surface analytical techniques. 

Samples from many industrial sources are often contaminated at the surface by processing agents or adventitious post-process contaminants. Detection of specific contaminant molecules on surfaces by SSIMS is, of course, an exercise similar to detection of additive molecules migrating to polymer surfaces. However, in case of contaminants the problem is often localised and the microanalytical/imaging capability of SSIMS is called upon. As the primary ion beam can be focused to a very small spot size (a few /xm) even very small defects can be analysed allowing locally resolved chemical surface identification by microanalytical SSIMS. Additive mapping has been used for the identification of contaminations [823]. Lloyd et al. [794] have described identification of a hexamethylene tetra-methyldiamine deposit on interior automotive parts. Another typical example concerns the behaviour of a non-woven PP fibre product with surface contamination by dimethylsilicone (DMS). The distribution of DMS over the 30 /xm PP fibres was mapped [824]. The sensitivity of SSIMS to molecular additives and surface contamination has been illustrated by Weng et al. [825] who identified PDMS (m/z 28, 73, 147, 207, 221, etc.) and palmitic/stearic acids (m/z 239, 257, 267, 285) in polybutadiene copolymers (Fig. 5.25) by means of ToF-SIMS. SSIMS is... 

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