Depth resolution physical processes

Each analytical technique discus.sed in this chapter has its own advantages and disadvantages, arising from both the physical processes involved and technical requirements. The theory behind each of the techniques would in it.self fill a book, whereas the present purpose was to set out briefly the depth profiling approach as it related to each. The theories of sputtering and of depth resolution have al.so been the subject of many publications. Individual applications (corrosion, semiconductors, catalysis, organic materials, etc.) will be described separately in this volume. 

Cesium-137 is an impulse marker where the subsurface peak of maximum activity (or first appearance of activity) is used to measure accumulation rates. However, the resolution of this peak and depth of first appearance can be altered by physical and biological mixing processes. Feeding activities of benthic... 

Our province is chemical and biochemical rather than physical or technical only passing reference is made to metallic solids or unstable species, or to practical NMR spectroscopy. Our aim is depth as well as breadth, to explain the fundamental processes, whether of nuclear magnetic shielding, spin-spin coupling, relaxation, or the multiple pulse sequences that have allowed the development of high-resolution studies of solids, multidimensional NMR spectroscopy, techniques for sensitivity enhancement, and so on. 

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