Evidence investigation analysis techniques

There are still other surface analysis techniques including ellipsometry, surface enhanced Raman scattering, light scattering, nano-hardness measurements etc. which are used for specific investigations. It is, however, already evident from this discussion that many new and powerful techniques now are available which offer the capability of investigating various aspects of polymer surfaces on a molecular level. Some of those techniques are surface specific while others can be used for the analysis of buried interfaces, too. 

Like other accident analysis techniques, the event and causal factors chart should be initiated as soon as the investigation begins and developed as evidence is collected. A detailed chart is developed during the investigation it is then reduced to an executive summary containing only key events and causal factors to serve as a report illustration. 

Work has also been conducted that involved the investigation, via infrared spectroscopy, of matrix-isolated, plutonium oxides (40), with the appropriate precautions being taken because of the toxicity of plutonium and its compounds. A sputtering technique was used to vaporize the metal. The IR spectra of PuO and PUO2 in both Ar and Kr matrices were identified, with the observed frequencies for the latter (794.25 and 786.80 cm", respectively) assigned to the stretchingmode of Pu 02. Normal-coordinate analysis of the PUO2 isotopomers, Pu 02, Pu 02, and Pu 0 0 in Ar showed that the molecule is linear. The PuO molecule was observed in multiple sites in Ar matrices, but not in Kr, with Pu 0 at 822.28 cm" in the most stable, Ar site, and at 817.27 cm" in Kr. No evidence for PuOa was observed. 

As is evident in the many examples selected in this chapter to illustrate the molecular characterisation and analysis of polymer degradation and oxidation processes, almost, without exception, each study or investigation cited has involved use of more than one analytical method or characterisation technique, often many more than two. This clearly emphasises the importance of using a multi-technique approach to provide supportive, complementary and confirmatory information, since each technique or method yields a different aspect of the degradation/oxidation process in polymers. 

In addition to the indirect experimental evidence coming from work function measurements, information about water orientation at metal surfaces is beginning to emerge from recent applications of a number of in situ vibrational spectroscopic techniques. Infrared reflection-absorption spectroscopy, surface-enhanced Raman scattering, and second harmonic generation have been used to investigate the structure of water at different metal surfaces, but the pictures emerging from all these studies are not always consistent, partially because of surface modification and chemical adsorption, which complicate the analysis. 

Within the past two decades, the importance of nuclear magnetic resonance (n.m.r.) spectroscopy has enlarged tremendously. Its advantages over other methods in the structural and conformational analysis of such complex molecules as natural products, and particularly with regard to the still-increasing importance of medical investigations using n.m.r. techniques, is abundantly evident. Because destruction of the sample is avoided, different n.m.r. experiments can be performed repeatedly, and... 

In addition to the techniques already discussed, aspects of MC formation in LB films have been investigated by Rutherford backscattering (RBS) (65) and fluorimetry (17,49,50.76,79,81,83,84). The results from the RBS analysis of H2S-exposed CdAr films provided evidence for the formation of spheroidal CdS particles. Investigations of the fluorescence properties of MC particles in LB films are discussed later. 

Early investigations were based largely on the ability to separate solid adducts whose composition was determined by analysis. More recently spectroscopic techniques have been used and naturally, in view of the strong colours often produced, visible spectroscopy has proved popular. However this does not in general provide conclusive evidence of the species present. A big impetus to the study of these interactions... 

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