SIMS systems

All commercially available SIMS systems have in common some type of computer automation, an ion source, a high-vacuum environment, and some type of mass spectrometer. While the specifics may vary from system to system, the basic requirements are the same. The hardware feature that tends to distii uish the various systems is the type of mass spectrometer used. These fall into three basic catego-... 

The SIMS system is mounted on a UHV spectrometer which also has XPS, UPS, LEED and thermal desorption capabilities ( ). Heating is achieved by electron bombardment from a filament mounted on the manipulator behind the sample. Cooling is achieved by circulating liquid N2 or He. Temperatures of 25K can be reached. The samples used, Ni(lOO), Cu(17%) Ni(83%) (100) and (111) and Ag(lll) were oriented within 1 and cleaned in situ by standard heating and Ar ion sputtering procedures. 

SPMs such as AFM, FFM, and SSPM were performed with a SEIKO SPA-300 unit together with an SPI-3700 control station. Details for fluorescence microscopy by SNOAM based on a modified SEIKO SPA-300 unit with an SPI-3700 control station were reported previously [27-33]. Conventional fluorescence microscopy was carried out with a Nikon XF-EFD2 fluorescence microscope [40]. SIMS was performed with a Perkin Elmer PHI model 6600 SIMS system with a Ga liquid metal ion source (beam diameter ca. 80 nm). For mapping of F negative secondary ions, a width of ca. 50 pm was scanned with 256 lines. 

The basic elements comprising a SIMS system are an ion source and a mass spectrometer (Fig. 6.4). Maintaining the analysis chamber under ultra-vacuum limits the contamination of the fresh surfaces exposed during analysis. The vacuum system comprises an introduction chamber enabling several samples to be introduced without deteriorating the vacuum. With the impact of the primary ions, secondary electrons are also produced. Addition of a detector... 

Gaskell and co-workers [207a,b] attempted to perform quantitative determin-tions with the steroid series. They used BjE linked scan with SIM system coupled with GC/MS. 

In its most elementary form, a SIMS system consists of a source of primary ions, a sample holder, secondary ion extraction optics, a mass spectrometer, and an ion detector, all housed in a UHV compartment. Systems are also equipped with data processing and output systems. A schematic diagram of part of a SIMS system with a quadrupole mass analyzer is shown in Fig. 14.38. The design and operation of mass spectrometers is covered in Chapter 9 and will be only briefly reviewed here. 

The three most common types of mass analyzers in SIMS systems are (1) double focusing magnetic sector instmments, (2) time of flight (TOF) mass spectrometers, and (3) quadru-pole mass spectrometers. The choice of mass analyzer depends on whether dynamic or static SIMS is needed, on the requirements of mass range and resolution, and on transmission efficiency, among other factors. The mass analyzers have been discussed in Chapter 9 in detail and this chapter should be reviewed as necessary. 

The liquid SIMS system comprises a target stage mounted on the tip of an introduction probe, a source for the primary ionization beam (commonly known as a gun ), and a source comprising beam focusing, extraction, and exit lenses to shape the secondary ion beam and inject it into the mass analyzer (Figure 1). 

Thus, when investigating the nature and mechanism of adhesion between an adhesive, coating or polymer matrix and the substrate, it is important to consider the possibility of primary bond formation in addition to the interactions that may occur as a result of Dispersion forces and Poiar forces. In addition to the Adsorption theory of adhesion, adhesion interactions can sometimes be described by the Diffusion theory of adhesion, Electrostatic theory of adhesion, or Mechanical theory of adhesion. Recent work has addressed the formation of primary bonding at the interface as a feature that is desirable from a durability point of view and a phenomenon that one should aim to design into an interface. The concept of engineering the interface in such a way is relatively new, but as adhesives become more widely used in evermore demanding applications, and the performance XPS and ToF-SIMS systems continues to increase, it is anticipated that such investigations can only become more popular. 

After stress, the calcium electrodes were washed off with deionized water and blown dry in the room with yellow lights, and packaged under A1 foil for transportation to the TOF-SIMS system (Charles Evans Associates), where they were inserted with minimal (but not zero) exposure to room light into the vacuum systenL A Ga ion beam at 7.5 keV generated the signal. The images were acquired fi om an 80 /xm x 80 /xm raster scan the beam size is about 1 xm for the spatial maps. The Tof-Pak software firom Phi was used for analysis. To gain access to the ITO surface, the device was immersed in a beaker of toluene for -30-60 sec. the films came off readily. 

NanoSIMS has been optimized for high lateral resolution SIMS analysis. Indeed, NanoSIMS is the only dynamic SIMS system to allow simultaneously a high... 

SIMS systems capable of imaging can be used to. study corrosion samples in plan view or in cross section. The choice of primary ion should be of one that enhances the detection of the major products Cs is the most suitable since it enhances the production of electronegative species such as O. H and oxide molecular fragments. The beam currents used should be such that the entire oxide thickness can be profiled in a reasonable time typical sputter erosion rates in oxides are 3-5 pm/h for a I pA beam rastered over a 250 pm- area. Ion images collected should reflect the possible oxide combinations, e.g.. FeO for a simple Fe oxide, or FeCrO" for an oxide believed to contain both Fe and Cr. 

Quantitative analysis with TOF-SIMS is challenging because the yield of seeondary ions depends on several factors and is not directly proportional to concentration. The ion yields vary, for instance, due to the surface composition of the sample. This means that the ion yields of the same analyte differ from each other when the chemical environment of the analyte changes. Also sputtering of the sample can cause chemical enviromnent changes during the analysis. Therefore, comparison between samples is difficult. This problem is called matrix effects, and it cannot be totally avoided even in modem SIMS systems (Belu et al., 2003 Hagenhoff, 1995). 

Our static SIMS system (19) operated with an Ar energy of 10 KeV. UHV conditions were maintained. The resolution of the instrument is about 1 part in 17,000. 

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