By using mass spectrometry to analyze the atomic and molecular secondary ions that are emitted from a solid surface when bombarded with ions, one obtains detailed information about the chemical composition of the surface. A time-of-flight mass spectrometer is especially suitable for the analysis of secondary ions because of its high transmission. high mass resolution, and ability to detect ions of different masses simultaneously. By using a finely focused primary ion beam it is also possible to analyze microareas and generate surface images with a lateral resolution of 0.1 pm or less. Static time-of-flight secondary ion mass spectrometry (TOF-SIMS) allows monolayer imaging and local analysis of monolayers with high sensitivity, a wide mass range, high mass resolution, and high lateral resolution. Besides information on elements and isotopes. the technique yields direct information on the molecular level and can also be used to analyze surface species of high molecular mass that are thermally unstable and cannot be vaporized. The method can be applied to practically all types of materials and sample forms, including insulators in particular.In this article the basic principles of TOF-SIMS are explained. and its analytical capabilities for both large-area and imaging applications arc illustrated by examples. These include silicon surfaces (both uniform and structured), thermally unstable organic molecules on surfaces, synthetic polymers. and synthetically prepared molecular surface films, particles, and fibers. Emitted neutral particles can also be analyzed by post-ionization with a laser, and the possibilities of this technique are discussed.

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would be futile to check the validity of Equation 4from the value of the yintercept of the straight line of unit slope that was obtained experimentally. The unexpected pH dependence that was found in the region, 8.5 < pH < 9.5, cannot be explained unless further work is carried out with a single reagent rather than the commercial extractants which are invariably mixtures of organic reagents.A plot of log D vs. pH for the extraction of Cu2+ is included in Figure 1 for the purpose of comparison with the corresponding plot for the extraction of Ni2+. In the region, 1.0 < pH < 3.5, the slope of the log D vs. pH plot for Cu2+ is 0.7 and in the region 5. < pH < 6.5, the slope is 3.1. In addition to these two regions in which the pH dependence resembles that of the Ni2+ extraction, there is an intermediate region, 3.5 < pH < 5., in which the pH seems to have little effect on the extraction of Cu2+. The complexity of the extraction system is such that no simple explanation can be given for the behavior of Cu2+.

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