Time-of-Flight - Secondary Ion Mass Spectroscopy

SIMS is the most commonly used of the surface mass spectroscopy techniques. SIMS analyses the secondary ions ejected from a sample following bombardment with a primary ion beam, usually argon ions. The impact of the primary ion causes an atomic-scale collision cascade within the surface layers of the sample and, at points remote from impact, secondary ions are ejected from the surface. These ions are then determined by MS. 

There are two modes of operating SIMS static and dynamic. 

Static SIMS (SSIMS) operates under non-damaging conditions. It gives good information on molecular content and, like Auger spectroscopy, can be used for surface micro-analysis at high spatial resolution. 

The most widely used method of SSIMS is ToF-SIMS. This uses ToF-MS which provides optimum sensitivity and mass resolution for secondary ions. 

With the latest ToF-SIMS instruments mass resolutions of 10 to 10 atomic mass units (amu) are achievable with sampling depths of greater than 1 nm. This has two main advantages. Firstly, the sensitivity is increased, allowing peaks to be resolved where previously there had been overlap (i.e., two peaks at nominally the same mass). This now enables ToF-SIMS to be sensitive to ppm/ppb levels of surface species. Secondly, mass resolution enables very accurate mass measurement so that empirical formulae can be calculated from the measured accurate mass, making unknown peak identification more certain. 

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The brief history, operation principle, and applications of the above-mentioned techniques are described in this chapter. There are several other measuring techniques, such as the fluorometry technique. Scanning Acoustic Microscopy, Laser Doppler Vibrometer, and Time-of-flight Secondary Ion Mass Spectroscopy, which are successfully applied in micro/nanotribology, are introduced in this chapter, too. 

Wang, D., Jones F.R. and Denison, P. (1992a). Surface analytical study of the interaction between r-aminopropyltriethoxysilane (APS) and E-glass surface. Part 1-Time of flight secondary ion mass spectroscopy. J. Mater. Sci. 27, 36-48. 

Time-of-Flight Secondary Ion Mass Spectroscopy Chemical Structure of the Film... 

The time-of-flight secondary ion mass spectroscopy (ToF-SIMS) analysis was performed on a CAMECA ION-TOF Model IV spectrometer. This instrument was equipped with a reflection-type ToF mass analyzer and a pulsed 25 kV primary... 

Time-of-flight secondary ion mass spectroscopy (TOF-SIMS)15 has been used for observing the initiating species in anionic ring-opening polymerizations of D3. The PDMS mass spectrum shows peaks of varying intensity with local maxima every 3 silicon repeat units. This distribution is attributed to the relative concentrations of the three initiating species, II, 12 and 13, shown in equation 2 which can be determined from the peak intensities. 

This chapter describes the results of an ongoing study we are conducting into the nanoscale mechanical properties, chemical composition and structure of healthy enamel, carious lesions and the acquired salivary pellicle layer. A variety of material characterization techniques are being used, including nanoindentation, scanning electron microscopy (SEM), electron microprobe analysis (EMPA), scanning acoustic microscopy, atomic force microscopy (AFM) and time-of-flight secondary ion mass spectroscopy (TOF SIMS). 

Figure 7.4. Time-of-flight secondary-ion mass spectroscopy (ToF-SIMS) image of the distribution of Fe on a cross section of a trembling aspen (Populus tremuloi desMmchx ) root embedded in clayey soil material. The Fe values are normalized to the total ion yield of the surface. The bar is 100 (im. (From Martin et al., 2004.)...

Over the last decade, SIMS and XPS have been shown to be powerful complementary techniques for determining the interfacial chemistries of polymers [68]. The surface chemical structure of aliphatic polyanhydride films has been examined using time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) [65, 66]. The Cls and Ols core level spectra are displayed for the homologous series of aliphatic polyanhydrides in Fig. 12. The main peak at 285 eV corresponds to the C-H. The peak at 289.5 eV arises from 0-C=0. The XPS data confirmed the purity of the surface, and the experimental surface elemental ratios were in good general agreement with the known stoichiometry of polyanhydrides. 

Time-of-flight secondary-ion mass spectroscopy (TOF-SIMS)... 

Direct measurement of the adsorbed particles has proven difficult because of their weak binding to the surface. Nevertheless, the adsorbed colloidal particles have been detected by ion microprobe analysis [8], atomic force microscopy (AFM) [9, 10] and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) [10]. AFM results ofVan Roy and coworkers ]10] are shown in Fig. 3, along with their proposed nucleation and growth mechanism on the aluminum surface. These results demonstrate that under the conditions of these experiments, the adsorbed particles are flat with 7 to 8 nm thickness and 100 to 300 nm in diameter. According... 

We first have confirmed the presence of polymeric materials in the SEI by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), time of flight-secondary ion mass spectroscopy (TOF-SIMS), and proton nuclear magnetic resonance spectroscopy ( H-NMR), as exemplified in Figs. 4.7 and 4.8. The FTIR and XPS (01s) spectra indicated the presence of C = C bonds and polymeric materials, respectively. The TOF-SIMS revealed the existence of... 

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