Surface chemical analysis etched surfaces

The interactions of ions with surfaces have many important applications that include sputter cleaning, ion implantation, ion etching, and surface chemical analysis (SIMS and ISS) [56, 61,64, 84, 117, 129-133]. Discuss each of these processes and by reviewing recent papers in the literature describe a case history of the application of each of these processes. Theories of high-energy ion-surface interactions have been proposed. Discuss the various models that explain the phenomena. 

The surface chemical analysis made possible by XPS has proved useful in a number of areas. Simple detection of surface contamination has already been mentioned another technically important area is the detection of changes in surface functionality introduced by treatments such as plasma and flame modification and chemical etching. These treatments are extensively used in practice to modify surface properties such as adhesion and wettability and the use of XPS and other surface analysis techniques permits one to associate these changes with the introduction of specific chemical functionality at the surface. Excellent entries into the extensive literature in this area may be found in the monograph by Garbassi et al. (1994) and the review by Briggs (1990). 

In addition to the above considerations, which are inherent to the techniques themselves, the artefacts induced by Ar+ etching [47] should be also borne in mind. Although the latter procedure is generally unavoidable when surface chemical analysis has to be extended into the sample, its effects on the alteration of the true chemical composition must be realized and taken into account. The reader is referred to the. several reviews dealing with this topic 47 (as well as to Chapters 6-9), while some Ar -induced artefacts will be discussed in the description of the surface analysis of Si/SiOi interfaces. 

Ion beams provide useful information either as a diagnostic tool or as a precision etching method in adhesion research. The combination ISS/SIMS method used along with other techniques such as SEM provides a powerful tool for elemental analysis of surface composition. These results, as well as earlier work in this laboratory, indicate that the surface composition can be significantly different from the bulk due to contamination, selective chemical etching and segregation. These same techniques also provide an analysis of the mode of failure in adhesive joints. Many failures classified as "adhesive" on the basis of visual inspection are frequently mixed mode failures or failures at a new interface containing elements of both adhesives and adherend. 

Some tubes were split open and subsequent examination showed the presence of very hard deposits on the surface (Figure 7.32). Isolated, but deep pits were present under the hard deposits (Figure 7.33). The measured thickness of the tube, mechanical tests, chemical analysis and etching showed the tubes to conform to the properties specified for SA 179 tubes. 

Figure 2.17. Electron spectroscopy for chemical analysis ESCA) spectra of organometallic polymer films before and after exposure to oxygen plasma. The silicon 2p transition page 99) is shifted from 99.7 to 102.4 eV. The magnitude of the shift is consistent uMh conversion to SiO, where x is between 1.5 and 2. The Sn 3d transitions of the organotin compound above) undergo a similar shift 1.7 eV), consistent with generation of a SnOx surface, where x is again between 1.5 and 2. Argon sputter etching followed by ESCA analysis indicates that these oxide films are less than 100 A thick.

Etching has a profound effect on the surface chemistry of the fluoropolymers. Electron spectroscopy for chemical analysis (ESCA) also known as x-ray photoelectron spectroscopy (XPS) is a technique that has been used to study the chemical composition of surfaces. ESCA does not detect hydrogen, and elemental compositions exclude this element. Results of surface chemical composition of fluoropolymers have been summarized in Table 7.1. The consistent changes in surface composition of fluoropolymers because of treatment are a reduction in fluorine and/or chlorine content, and an increase in carbon and oxygen content. The treated PTFE surface is virtually comprised of carbon and oxygen and a small amount of fluorine. 

In a report on the determination of oxygen in Cu, steel, and Sn at 0.1—0.01 p.p.m. concentrations, Kapitza et al. note that agreement with conventional vacuum fusion methods of oxygen analysis is only good if the sample surface is not etched before chemical separation (a metal bath fusion and adsorption of C 02) this indicates that a considerable proportion of the oxygen is present at the metal surface. 

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