High-energy resolution fluorescence detection

The X-ray absorption spectroscopy (XAS) methods provide information about the electronic and structural properties of matter. Thus, X-ray absorption nearedge spectroscopy (XANES) is adequate for the observation of local electronic and geometric structures of elements, while extended X-ray absorption fine structure (EXAFS) provides information concerning the coordination environment of metals, metal ions, and nonmetals. To improve time resolution and spectral quahty, sophisticated techniques such as EDXAFS (energy-dispersive X-ray absorption fine structure spectroscopy) and HERFD XAS (high-energy resolution fluorescence detection X-ray absorption spectroscopy) have been developed. All mentioned X-ray methods have a common requirement for high-briUiance X-ray sources such as available at a synchrotron. 

The nucleic acid to be labeled can be divided into four types natural enzymatically amplified cloned or synthetic. The selection of an appropriate label for a given probe may depend on many factors (Table 7.1). Localization of target nucleic acid in a cell often requires high resolution. This can be obtained by low energy radioisotopes, fluorescent dyes, or enzyme detection systems that limit the spread of the generated product as much as possible. On the other hand, dot hybridization requires high detectability while resolution is not a priority. Quantification is better with radioisotope labels than with biotin systems due to a higher sensitivity, while the... 

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