Static SIMS analyses

Static SIMS Analyses. Static SIMS spectra of PMMA and PET obtained with 2.1013 Xe+/cm2 are presented in Figure 4. They are totally comparable with already published spectra of the same polymers Q, 4, , li). Figure 4 illustrates the greater molecular specificity of static SIMS compared to XPS. 

Previous static SIMS analyses have also shown (2) that the plasma treatment may induce fragmentation of the polymer backbone and some homogeneization of the polypropylene surface composition. Figure 6a shows static SIMS spectra obtained on a virgin polypropylene sample and Figure 6b on polypropylene which was treated in a N2 plasma for 7 seconds. 

In a molded polymer blend, the surface morphology results from variations in composition between the surface and the bulk. Static SIMS was used to semiquan-titatively provide information on the surface chemistry on a polycarbonate (PC)/polybutylene terephthalate (PBT) blend. Samples of pure PC, pure PBT, and PC/PBT blends of known composition were prepared and analyzed using static SIMS. Fn ment peaks characteristic of the PC and PBT materials were identified. By measuring the SIMS intensities of these characteristic peaks from the PC/PBT blends, a typical working curve between secondary ion intensity and polymer blend composition was determined. A static SIMS analysis of the extruded surface of a blended polymer was performed. The peak intensities could then be compared with the known samples in the working curve to provide information about the relative amounts of PC and PBT on the actual surface. 

D. Briggs. Polymer. 25, 1379, 1984. Review of static SIMS analysis. 

Static SIMS analysis of plasma treated polymer surfaces. 

D. Briggs. Org. Mass Spectrom. 22, 91, 1987. Static SIMS analysis of copolymers. 

Which type of primary ion source can provide better static SIMS analysis Why do we not recommend using the smallest diameter of a primary beam for ToF SIMS imaging ... 

Static SIMS analysis provides much information about the molecular structure of adsorbed species and the chemical composition of surfaces. However, the interpretation of SIMS spectra is often not straight forward. The reason is that the spectra include ionic species that are the result of gas phase collision reactions taking place in the immediate vicinity of the surface. 

Static SIMS Analysis of the top most monolayer with minimal molecular damage noted in subsequent ion impacts (primary ion dose is less than 1% of the surface density)... 

Environment. Detection of environmental degradation products of nerve agents directly from the surface of plant leaves using static secondary ion mass spectrometry (sims) has been demonstrated (97). Pinacolylmethylphosphonic acid (PMPA), isopropylmethylphosphonic acid (IMPA), and ethylmethylphosphonic acid (EMPA) were spiked from aqueous samples onto philodendron leaves prior to analysis by static sims. The minimum detection limits on philodendron leaves were estimated to be between 40 and 0.4 ng/mm for PMPA and IMPA and between 40 and 4 ng/mm for EMPA. Sims analyses of IMPA adsorbed on 10 different crop leaves were also performed in order to investigate general apphcabiflty of static sims for... 

Applications of ISS to polymer analysis can provide some extremely useful and unique information that cannot be obtained by other means. This makes it extremely complementary to use ISS with other techniques, such as XPS and static SIMS. Some particularly important applications include the analysis of oxidation or degradation of polymers, adhesive failures, delaminations, silicone contamination, discolorations, and contamination by both organic or inorganic materials within the very outer layers of a sample. XPS and static SIMS are extremely comple-mentar when used in these studies, although these contaminants often are undetected by XPS and too complex because of interferences in SIMS. The concentration, and especially the thickness, of these thin surfiice layers has been found to have profound affects on adhesion. Besides problems in adhesion, ISS has proven very useful in studies related to printing operations, which are extremely sensitive to surface chemistry in the very outer layers. 

Static SIMS is labeled a trace analytical technique because of the very small volume of material (top monolayer) on which the analysis is performed. Static SIMS can also be used to perform chemical mapping by measuring characteristic molecules and fiagment ions in imaging mode. Unlike dynamic SIMS, static SIMS is not used to depth profile or to measure elemental impurities at trace levels. 

Figure 1 shows a positive static SIMS spectrum (obtained using a quadrupole) for polyethylene over the mass range 0—200 amu. The data are plotted as secondary ion intensity on a linear y-axis as a function of their chaige-to-mass ratios (amu). This spectrum can be compared to a similar analysis from polystyrene seen in Figure 2. One can note easily the differences in fragmentation patterns between the...

Another example of static SIMS used in a more quantitative role is in the analysis of extmded polymer blends. The morphology of blended polymers processed by extrusion or molding can be affected by the melt temperature, and pressure, etc. The surface morphology can have an effect on the properties of the molded polymer. Adhesion, mechanical properties, and physical appearance are just a few properties affected by processing conditions. 

In addition to data obtained using the spectral mode of analysis, it is often important to know the location of a particular chemical group or compound on the sample surface. Such information is achieved by static SIMS chemical mapping—a procedure in which a specific chemical functionality on the material is imaged, providing information as to its lateral distribution on the surface. 

Static SIMS has been demonstrated to be a valuable tool in the chemical characterization of surfaces. It is unique in its ability to provide chemical information with high surface sensitivity. The technique is capable of providing mass spectral data (both positive and negative spectrometry), as well as chemical mapping, thereby giving a complete microchemical analysis. The type of information provided by... 

If it is required that the surface of the sample remains undisturbed during analysis, SIMS must be carried out at very low surface removal rates, typically about 10 monolayer/s. The terms static and dynamic are used to divide the sputtering rate of the sample into regimes where only surface species are observed (static SIMS) or where surface and bulk species are observed (dynamic SIMS). The static limit is usually considered to be <10 ions/cm impinging on the sample surface. Under these conditions, only about 1/1000 atoms on the surface of the sample are struck by a primary ion. 

Static SIMS, used for sub-monolayer elemental analysis. At the lowest current densities and hence the lowest rates of erosion, a monolayer on the surface has a lifetime of many hours. The surface is essentially unchanging during the experiment, but a vacuum system at a pressure of 10 10mbar is needed to allow adequate time to complete the analysis. In favourable cases, as little as 0.1% of a monolayer of material can be detected. 

D. Briggs, Surface Analysis of Polymers by XPS and Static SIMS, Cambridge University Press, Cambridge, 1998. 

K. Keune and J. J. Boon, Enhancement of the static SIMS secondary ion yields of lipid moieties by ultrathin gold coating of aged oil paint surfaces, Surface and Interface Analysis, 36, 1620 1628 (2004b). 

Newmann, J. G., Carlson, B. A., Michael, R. S., Mounlder, J. F. and Hohlth, T. A., Static SIMS Handbook of Polymer Analysis. Perkin Elmer Corp., Physical electronocs Division, Elden Prairie, Minnesota (1991). 

TOFSIMS analyses were performed on a Kratos PRISM instrument. It was equipped with a reflectron-type time-of-flight mass analyzer and a pulsed 25 kV liquid metal ion source of monoisotopic 69Ga ions with a minimum beam size of 500 A. Positive and negative spectra were obtained at a primary energy of 25 keV, a pulse width of 10-50 ns, and a total integrated ion dose of about 10" ions/cm2. This is well below the generally accepted upper limit of 5 x 1012 ions/cm2 for static SIMS conditions in the analysis of organic materials [12], The mass resolution at mass 50 amu varied from M/AM= 1000 at 50 ns pulse width to about 2500 at 10 ns pulse width. 

Static SIMS, especially high-mass-resolution TOFSIMS, is a powerful tool for the study of silane films. The accurate mass determination capability of high-mass-resolution SIMS analysis of organic materials has demonstrated that many peaks from organic materials consist of two or more components. Hence ion identification in SIMS with low mass resolution may be ambiguous. 

In secondary ion mass spectrometry (SIMS) the sample surface is sputtered by an ion beam and the emitted secondary ions are analyzed by a mass spectrometer (review Ref. [360]). Due to the sputtering process, SIMS is a destructive method. Depending on the sputtering rate we discriminate static and dynamic SIMS. In static SIMS the primary ion dosis is kept below 1012 ions/cm2 to ensure that, on average, every ion hits a fresh surface that has not yet been damaged by the impact of another ion. In dynamic SIMS, multiple layers of molecules are removed at typical sputter rates 0.5 to 5 nm/s. This implies a fast removal of the topmost layers of material but allows quantitative analysis of the elemental composition. 

It is a remarkable feature of secondary ion mass spectrometry (SIMS) that considerable chemical information is accessible through the procedurally simple physical technique of sputtering. SIMS--espec ia 11 y under low primary ion flux conditions ("static SIMS," a 1 s o known as "molecular SIMS" when applied to compounds)—provides information on molecular weight and molecular structure and allows isotopic analysis. The surface sensitivity of SIMS permits its use in imaging, in monitoring of surface... 

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