Atomic fluorescence history

Table 1 Important steps in the history of atomic absorption (AAS), plasma atomic emission (plasma AES), atomic fluorescence (AFS), and plasma mass spectrometry (plasma MS)...

Chemical analysis of the metal can serve various purposes. For the determination of the metal-alloy composition, a variety of techniques has been used. In the past, wet-chemical analysis was often employed, but the significant size of the sample needed was a primary drawback. Nondestmctive, energy-dispersive x-ray fluorescence spectrometry is often used when no high precision is needed. However, this technique only allows a surface analysis, and significant surface phenomena such as preferential enrichments and depletions, which often occur in objects having a burial history, can cause serious errors. For more precise quantitative analyses samples have to be removed from below the surface to be analyzed by means of atomic absorption (82), spectrographic techniques (78,83), etc. 

It is a remarkable fact that the contemporary history of absorption and emission spectroscopy began simultaneously, from the simultaneous discoveries that Bunsen and Kirchhoff made in the middle of the 19th century. They observed atomic emission and absorption lines whose wavelengths exactly coincided. Stokes and Kirchhoff applied this discovery to the explanation of the Fraunhofer spectra. Nearly at the same time approximately 150 years ago, Stokes explained the conversion of absorbed ultraviolet light into emitted blue light and introduced the term fluorescence. Apparently, the discovery of the Stokes shift marked the birth of luminescence as a science. 

Technical examination of objects coated with a protective covering derived from the sap of a shrubby tree produces information that can be used to determine the materials and methods of manufacture. This information sometimes indicates when and where the piece was made. This chapter is intended to present a brief review of the raw material urushi, and the history and study of its use. Analytical techniques have included atomic absorption spectroscopy, thin layer chromatography, differential thermal analysis, emission spectroscopy, x-ray radiography, and optical and scanning electron microscopy these methods and results are reviewed. In addition, new methods are reported, including the use of energy dispensive x-ray fluorescence, scanning photoacoustical microscopy, laser microprobe and nondestructive IR spectrophotometry. 

The mass spectrometry (MS) of nudeic acids (NAs) has a history similar to that of proteins and other biomolecules. Although earlier work had been made possible by field desorption and fast atom bombardment (FAB) and other ionization techniques, the field did not really take off until the soft ionization techniques of electrospray ionization (ESI) [1] and MALDI [2] became available. Even with the benefits of these new ionization techniques, however, the analysis of NAs turned out to be substantially more difficult than that of proteins and, as a result, MS-based technologies are not nearly as prominent in genetics and genomics as they are in proteomics. The widespread utilization of MS for NA analysis has been further limited by the competition of powerful techniques that can rely on amplification, hybridization, and fluorescence detection. MALDI-MS has found its place in these fields only more recently, and its performance must consistently be measured against that of the competing techniques in any given analytical task. 

Gate 42 [97] is interesting because various transition metal ions serve to switch on fluorescence by more-or-less same amounts. The surprise in this system [97, 98] is that transition metal ions were acting contrary to their normal behaviour. Transition metal ions have a history of quenching fluorescence very efficiently by several mechanisms heavy atom effects, PET, electronic energy transfers and... 

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