Metals SIMS analysis

It is worth noting, prior to citing actual metal atom studies, the recent secondary ion mass spectrometry (SIMS) on an argon matrix-isolated propene sample, demonstrating the applicability of SIMS analysis to the characterization of matrix-isolated species. The same group h s reported the first C NMR spectra of organic molecules trapped in an argon matrix. ... 

In addition to these numerous results, two other points are discussed by the authors fatty acid speciation and oil identification. These two aspects are developed in another publication written by the same authors [Keune et al. 2005]. The fatty acid speciation is based on the positive ion ToF-SIMS analysis and aims to prove if the fatty acids detected exist as free fatty acids, ester bound fatty acids or metal soaps. On account of the study of different standards, it is shown that when free fatty acids are present, the protonated molecular ion and its acylium ([M-OH]+) ion are detected. In cases of ester-bound fatty acid only the... 

For the TOF SIMS analysis, only slides treated with a natural pH HAPS solution were used. These were subsequently extracted with warm and hot water. They were mounted into a grid sample holder for transportation into a VG IX23S time-of-flight (TOF) SIMS instrument operating at a vacuum of < 10 Torr with a microfocused liquid Ga metal ion primary beam source (30 keVx 1.0 nA). For charge compensation, an electron flood gun was used. The working resolution of the spectrometer was determined from a lead phthalocyanine spectrum for Pb+ at mlz = 208 and the molecular ion at mlz = 720, it was 500 and 1000, respectively. 

Figure 6. Schematic diagram of the experimental set-up for dynamic SIMS analysis using a liquid metal substrate. Reproduced with permission from Ref. 103. Copyright 1983, Elsevier Science Pub. Co.

Materials. Biaxially oriented polypropylene (PP) films of 50 um thickness were obtained from 3M and have been described (2). PMDA-ODA (PI) was Kapton H polyimide from Dupont. Copper-plated PTFE films were obtained from Spire Corporation (Bedford, MA). They were prepared using the Ion Beam Enhanced Deposition (IBED) process in which a 100 nm thick Cu film was vapor-deposited onto a PTFE substrate in the presence of a beam of 400 eV Ar+ ions of 25 uA/cm2 (IQ). Shortly before SIMS analysis, the Cu film was removed slowly by peeling at 90° in ambient conditions. Metal-coated PI films were prepared by sputtering 50 nm Cr and 1 um Cu onto a 50 um thick Kapton film on both sides. Thermal annealing was performed in a vacuum chamber at 2xl0 6 torr using a quartz lamp as the heating source. The samples were held for 15 min at the desired temperature and then cooled down to ambient temperature inside the chamber for about 2 hours. Just prior to SIMS analysis, the metal films were peeled slowly at 90° and then immediately introduced into the vacuum chamber of the instrument. 

A more dramatic failure results in peel strengths of 0-10 g/mm and is characterized as an adhesive failure at the polyimide/metal oxide interface.This was the only failure mode observed in Ti and Zr films. Isotopically tagged water used with SIMS analysis shows that on annealing water reacts with the Ti with oxygen segregating to the metal/polyimide interface and hydrogen penetrating into the bulk of the Ti, in these samples. 

Be-evaporation at JET and boronization in other devices act as metallic markers and allow studies of material transport. Surface analysis of JET and TEXTOR tiles show very clearly that long-range transport is only observed for carbon. In addition to markers, 13C marked methane has been recently injected in various machines. As an example, Secondary Ion Mass Spectroscopy (SIMS) analysis of JET tiles show a strong enrichment of 13C on top of the surface of the inboard divertor tiles whereas no corresponding 13C was found in the outboard divertor. This proves that impurities are dragged towards the inboard divertor. However, the near top surface shows much more C and D than measured in deeper layers and on tiles from previous MKIIGB operation and no 13C could be identified on the shadowed regions of the divertor tiles. 

For SIMS analysis, the sample can be a solid material, a thin layer or particles supported on a substrate. It must be able to withstand ultra-vacuum, since volatile components may be redeposited during analysis. Because of the erosion of the sample during ion impact, any contamination layer can be eliminated prior to analysis. The preparation of the sample is thus subject to less severe conditions than for other surface analysis techniques. For the results of composition profiles to be significant the surface must, however, be flat at the scale of the ion probe. The use of a liquid metal ion gun will enable concentration profiles to be determined on grains of around 0.1 pm in diameter. 

The following examples reflect the main advantages of SIMS analysis the microanalysis of elements at trace level in the case of catalytic cracking catalysts (FCC). the sensitivity to light elements for the study of coke distribution and the possibility of providing composition profiles on zeolites modified by chemisorption of metals. 

Further evidence that the HP step is good for removing some metal ion contamination can be seen from the experiment that compared wafers cleaned by APM and APM, HP. Table II shows the results of the SIMS analysis. 

Surface characterization of mixed oxide coatings [37] by spectroscopic techniques shows surface enrichment with one of the metals. The surface of (H + Ru)02 appears to be enriched with Ti [38,39], and that of (Ru + Ir)02 with Ir [40-42]. The degree of enrichment depends on the method of preparation [40,43]. SIMS analysis, however, does not reveal the surface enrichment of Ti in the commercial RUO2 +1102 coatings [44],... 

Metals and alloys are in principle good materials for SIMS analysis. They are highly electric conductive materials and can easily be handled so as to obtain clean, flat, and smooth analyzable surfaces, and they are also usually ultrahigh-vacuum-friendly. However, archaeological and/or artistic metal objects do not always possess all of these properties due to degradation processes, which may chemically modify the external surface and deep regions of the samples. Nonconductive patinas and infiltrated compounds may often form as a result of long burial in soil or exposure to the atmosphere, and these have very different characteristics compared with those observed for metal materials. 

The spectra were acquired using a Physical Electronics PHI 7200 ToF-SIMS instrument (Physical Electronics, Eden Prairie, MN, USA), allowing parallel mass registration with high sensitivity and high mass resolution. A gallium liquid-metal ion (LMI) gun at 25 keV beam energy was used for spatially resolved ToF-SIMS analysis. The beam diameter was 0.25 p-m, the pulse width 100 ns and the TDC bin size 10 ns. A mass resolution m tsm) of 4500 at m/z = 29 was obtained. 

The lateral density of pinholes seen with the TOF-SIMS analysis suggests that pinholes are a major contributor to these observations. Even if one has two layers, and pinholes would presumably not be in register in the two layers, cathode metal would penetrate to the hole transport layer, and a relatively high hole current would result. This would be exacerbated by the fact that the small metal tip in the pinhole enhances the electric field. 

Surface analysis has made enormous contributions to the field of adhesion science. It enabled investigators to probe fundamental aspects of adhesion such as the composition of anodic oxides on metals, the surface composition of polymers that have been pretreated by etching, the nature of reactions occurring at the interface between a primer and a substrate or between a primer and an adhesive, and the orientation of molecules adsorbed onto substrates. Surface analysis has also enabled adhesion scientists to determine the mechanisms responsible for failure of adhesive bonds, especially after exposure to aggressive environments. The objective of this chapter is to review the principals of surface analysis techniques including attenuated total reflection (ATR) and reflection-absorption (RAIR) infrared spectroscopy. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) and to present examples of the application of each technique to important problems in adhesion science. 

A system has been constructed which allows combined studies of reaction kinetics and catalyst surface properties. Key elements of the system are a computer-controlled pilot plant with a plug flow reactor coupled In series to a minireactor which Is connected, via a high vacuum sample transfer system, to a surface analysis Instrument equipped with XFS, AES, SAM, and SIMS. When Interesting kinetic data are observed, the reaction Is stopped and the test sample Is transferred from the mlnlreactor to the surface analysis chamber. Unique features and problem areas of this new approach will be discussed. The power of the system will be Illustrated with a study of surface chemical changes of a Cu0/Zn0/Al203 catalyst during activation and methanol synthesis. Metallic Cu was Identified by XFS as the only Cu surface site during methanol synthesis. 

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