Static surface spectra

Unfortunately, PI of the PMDA-ODA type does not generate a highly characteristic static SIMS spectrum in either the positive or negative mode. A typical spectrum of a cleaned PI surface is shown in Figure 4. Spectra of many other commercial PI films have recently been published (18). Fragment 55 is C3H30+ formed by the carbonyl groups and two C atoms of... 

One of the most common modes of characterization involves the determination of a material s surface chemistry. This is accomplished via interpretation of the fiag-mentation pattern in the static SIMS mass spectrum. This fingerprint yields a great deal of information about a sample s outer chemical nature, including the relative degree of unsaturation, the presence or absence of aromatic groups, and branching. In addition to the chemical information, the mass spectrum also provides data about any surface impurities or contaminants. 

Static SIMS is appropriate for obtaining information on the lateral distribution of surface chemical species. A broad, defocussed ion beam is often used in order to minimise surface damage. In dynamic SIMS sample erosion takes place quite rapidly, and depth profiles are obtained by monitoring peak intensities in the mass spectrum of sputtered ions as bombardment proceeds. 

Static SIMS would be particularly appropriate to study films formed by silane coupling agents by virtue of its high surface sensitivity, its capability to detect all elements and isotopes, and because it provides molecular structural information on organic materials [9-12], So far, SIMS has rarely been used to study silane films. It was used, however, to detect covalent bonds between iron or chromium and silane films deposited on stainless steel [13, 14], Such bonds were indeed reported this claim was based on the presence of ions in the spectrum which were assumed to be FeOSi+ and CrOSi. However, these SIMS analyses were not done under static conditions, which had not yet been established at the time of these studies. 

In the absence of mechanical activation, the XPS spectrum is different from that obtained in the presence of mechanical activation. Thus, sulfur compounds that are formed on the surface (162 eV) appear in the spectra that are not present in the spectra for static immersion. Cutting produces a change in the surface chemistry and the reaction product formed appears to be similar to that obtained by mechanical activation. Thus, mechanical activity plus increased surface temperatures on a solid surface tend to promote surface chemical reactions. A lubricant interacting with metal oxide can produce entirely different reaction products from that of a lubricant interacting with rubbing metal surfaces. 

To a rather good approximation we can assume that all three above-mentioned electron-13C coupling tensors are axially symmetric and that the sum of their contributions determines the components of the shift tensor K. In this case the shape of the 13C NMR spectrum depends on the values of the 13C shift tensor K and K . K is the component of the 13C shift tensor normal, while the component is tangential to the C60 surface. In the static limit, the 13C NMR frequency is given by [120,121]... 

As mentioned in Sect. 3.1.1, the as-prepared (CH)X film surface is usually oxidized to some extent. Figure 23(a) and Fig. 23(b) show, respectively, the negative static SIMS spectra of a high density cis-(CH)x film before and after sputtering by Ar+ beam [193]. The negative ion spectrum for the as-received film is dominated in the low mass region by signals due to C2H (25 amu), C2... 

A surface analysis technique that has the potential to detect structural chemical changes in polymer surfaces, including low-molecular weight material formation, is static SIMS. Its capabilities for characterizing polymers by virtue of their fingerprint spectrum nave been amply demonstrated in recent years (5 6). The technique is more surface sensitive than XPS and can detect structural differences, even in hydrocarbons (7). It is, therefore, highly complementary to XPS. Nevertheless, only very few applications to the study of modified polymer surfaces have been published. Among these are reports on SIMS analysis of flame-treated polypropylene and plasma-fluorinated polyolefin surfaces (8 9). 

In our experiment, the compression strength of supports was tested by an intellect strength tester (Model ZQJ, China). Specific areas, pore volume and average pore diameters were measured by a static physical absorber (Model ASAP-2000, America). The surface of catalyst was observed under an electron microscope (Model JEM-1200EX). The crystal structure was detected by an X-ray fluorescence spectrometer (Model 3015, Japan). The content of Ru was detected by a plasma spectrum instrument (Model ICPS-IOOOII). 

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