Thin film analysis

This is becoming known by the above name but the name used in the seminal papers of Curme et al. and Spayd et al. of Eastman Kodak Company is multi layer film elements for clinical analysis 44-45). It is a technique which unites two aspects of clinical analysis. One is the procedure for carrying out quantitative tests on fibre strips. These strips may be dipped into a sample of urine and instantly reveal the concentration of up to 8 basic components it is an elegant variation of indicator paper. The other aspect is the increasing use being made of biological methods, particularly enzyme methods for clinical analysis. 

Approximately 10 pi of sample is required and after development, the density of the colour is measured via the transparent bottom layer by reflectance spectrophotometry. There is a relatively complex relationship between the signal and concentration, but with suitable transformations a perfectly acceptable calibration curve is obtained. 

The spotting may be done automatically, and the whole placed on a type of conveyor belt operation, so that it is possible to complete 3 analyses per min with a 7-min reaction time. 

The technical difficulties of making films which, both work and stay in place are immense. But now the breakthrough has happened, many other and more complex chemistries have been fixed on film. Film is available for urea, triglycerides and anylase in blood sera, and even ion selective electrodes have been adapted for the detection of metal ions such as Na +, K +, etc. in a single step. 

By virtue of its simplicity of operation and great chemical and biochemical adaptability it is coming into widespread use. 

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Feldman L C and Mayer J W 1986 Fundamentals of Surface and Thin Film Analysis (Amsterdam Elsevier)... 

Few-monolayer thin-film analysis, e.g., adsorbate and very thin-film reactions submicron detection of metal hydrides... 

Principles of Analytical Electron Microscopy (D. C. Joy, A. D. Romig, and J. I. Goldstein, eds.) Plenum Press, New York, 1986. Another book, more readily available, discussing all aspects of AEM. Approximately one-quarter of the book is devoted to EDS and a discussion of thin-film analysis in the TEM. 

The principle application of XRF thin-film analysis is in the simultaneous determination of composition and thickness. The technique has been used for the routine analysis of single-layer films since 1977 and multiple-layer films since 1986. Two main sources of publications in the fields are the annual volumes of Advances in X-Ray Analysis by Plenum Press, New York, and the Journal of X-Ray Spectrometry by Heyden and Sons, London. Typical examples on the analysis of single-layer films and multiple-layer films are used to illustrate the capabilities of the technique. 

Surface and Thin Film Analysis Principles, Instrumentation, Applications 11... 

Compared with the other methods of surface and thin film analysis, the main advantages of SNMS are ... 

An EDX spectrum typical of thin-film analysis in TEM/(S)TEM is shown in Eig. 4.26. It was obtained from a polycrystalline TiC/Zr02 ceramic by use of an Si(Li) detector at 100 keV primary electron energy. Eor spectrum recording the electron probe of approximately 1 nm in diameter was focused on the triple junction between the grains in the STEM mode (Eig. 4.26a). Besides the elements expected for the material under investigation, viz. Ti and Zr, Si, Ee, and Co were also detected, hinting at the presence of a (Ee, Co) silicide as an impurity. Eor ceramic materials it is known that... 

Jacobson, Anal. Chem. 69 (1997) 3747-3753. 3-120 L. C. Peldman, J. W. Mayer Fundamentals of Surface and Thin Film Analysis, North Holland, New York 1986. 

Therefore, this book is to give the analyst - whether a newcomer wishing to acquaint themself with new methods or a materials analyst needing to inform themself on methods that are not available in their own laboratory - a clue about the principles, instrumentation, and applications of the methods, techniques, and procedures of surface and thin-film analysis. The first step into this direction was the chapter Surface and Thin Film Analysis of Ullmann s Encyclopedia of Industrial Chemistry (Vol. B6, Wiley-VCH, Weinheim 2002) in which practitioners give briefly outline the methods. 

State-of-the-art TOF-SIMS instruments feature surface sensitivities well below one ppm of a mono layer, mass resolutions well above 10,000, mass accuracies in the ppm range, and lateral and depth resolutions below 100 nm and 1 nm, respectively. They can be applied to a wide variety of materials, all kinds of sample geometries, and to both conductors and insulators without requiring any sample preparation or pretreatment. TOF-SIMS combines high lateral and depth resolution with the extreme sensitivity and variety of information supplied by mass spectrometry (all elements, isotopes, molecules). This combination makes TOF-SIMS a unique technique for surface and thin film analysis, supplying information which is inaccessible by any other surface analytical technique, for example EDX, AES, or XPS. 

Benninghoven, A., and Cha, L. Z., TOF-SIMS—A Powerful Tool for Practical Surface, Interface and Thin Film Analysis," Vacuum of China,Vol. 5,2002,pp. 1-10. 

XPS is among the most frequently used techniques in catalysis. It yields information on the elemental composition, the oxidation state of the elements and, in favorable cases, on the dispersion of one phase over another [ J.W. Niemantsverdriet, Spectroscopy in Catalysis, An Introduction (2000), Wiley-VCH, Weinheim G. Ertl and J. Kiippers, Low Energy Electrons and Surface Chemistry (1985), VCH, Weinheim L.C. Feldman and J.W. Mayer, Fundamentals of Surface and Thin Film Analysis (1986), North-Holland, Amsterdam]. 

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