Chemical neutron activation

The chemical composition of particulate pollutants is determined in two forms specific elements, or specific compounds or ions. Knowledge of their chemical composition is useful in determining the sources of airborne particles and in understanding the fate of particles in the atmosphere. Elemental analysis yields results in terms of the individual elements present in a sample such as a given quantity of sulfur, S. From elemental analysis techniques we do not obtain direct information about the chemical form of S in a sample such as sulfate (SO/ ) or sulfide. Two nondestructive techniques used for direct elemental analysis of particulate samples are X-ray fluorescence spectroscopy (XRF) and neutron activation analysis (NAA). 

Another application involves the measurement of copper via the radioisotope Cu (12.6-hour half-life). Since Cu decays by electron capture to Ni ( Cu Ni), a necessary consequence is the emission of X rays from Ni at 7.5 keV. By using X-ray spectrometry following irradiation, sensitive Cu analysis can be accomplished. Because of the short range of the low-energy X rays, near-surface analytical data are obtained without chemical etching. A combination of neutron activation with X-ray spectrometry also can be applied to other elements, such as Zn and Ge. 

Radioactive nuclei are used extensively in chemical analysis. One technique of particular importance is neutron activation analysis. This procedure depends on the phenomenon of induced radioactivity. A sample is bombarded by neutrons, bringing about such reactions as... 

Heydorn K (1984) Neutron Activation Analysis for Chemical Trace Element Research. CRC Press, Boca Raton, Florida. 

Thus we shall be concerned with properties that furnish information about the nature of the ligands, the oxidation state of the metal, and the geometry of the field of ligands. Techniques such as radio-isotope tracer studies, neutron-activation analysis, and electron microscopy are powerful methods for locating a metal within constituents of the cell and are particularly suited to heavy-metal rather than organic drugs but since they do not provide information about the chemical environment of the metal they will not concern us here. After each section below we shall give an example, not necessarily from platinum chemistry, where the method has been used with success in biochemistry. 

Neutron activation Electron spectroscopy for chemical analysis (ESCA)... 

The reluctance of museum curators and collectors to allow permanent damage to antiquities was, until not long ago, the main reason for the small amount of analytical work done on ancient coins. This was understandable since performing chemical analysis required removing a sample from the coin or damaging its surface, which meant either the destruction or defacement of, at least, a portion of a coin. More recently, however, a number of nondestructive methods of analysis such as neutron activation, X-ray fluorescence, and some techniques of surface analysis have been successfully applied to obtain information about ancient coins and the people and societies involved in their production (Carter 1993 Barrandon et al. 1977). 

Chemical Analysis. The chemical composition of ancient objects is important for their authentication. The nature as well as the relative amounts of major, minor, and trace elements in any object are of use for determining the authenticity or otherwise of ceramics, glass, or alloys. A wide range of analytical techniques, depending on the nature of the material studied, have been used for this purpose, including X-rays fluorescence analysis, mass spectrometry, atomic absorption spectroscopy, and neutron activation analy-... 

An inscribed thick plate of brass attributed to the landing, in 1579, of Francis Drake on the coast of California, is retained in safekeeping at the University of California, Berkeley. Since its discovery, in the San Francisco Bay area in 1936, however, there have been doubts about the authenticity of the plate, although an early chemical study had apparently confirmed its authenticity. Regardless of this initial study, doubts about the origin of the plate persisted, and a new study, based on the composition of the brass as determined by neutron activation, X-rays fluorescence, and atomic absorption analysis was initiated to reevaluate the earlier authentication of the plate. The results of this study were then compared with the composition typical of brass from Drake s time as well as from modem brass, and it was then concluded that the plate was probably made during the latter part of the nineteenth century or the early years of the twentieth century (Hedges 1979). 

Harbottle, G. (1990), Neutron activation analysis in archaelogical chemistry, in Yoshihara, K. (ed.), Chemical Applications of Nuclear Probes, Topics in Current Chemistry, Springer, Berlin, Vol. 157, 57-91. 

Neff, H. (2000), Neutron activation analysis for provenance determination in archaeology, in Ciliberto, E. and G. Spoto (eds.), Modern Methods in Art and Archaeology, Chemical Analysis Series, Vol. 155, Wiley, New York, pp. 81-134. 

Study of chemical pathways in method development. Isotope dilution methods. Radioimmunoassay very important in biochemistry and medicine. Neutron activation analysis used for trace elements in geo-chemistry, semiconductor technology, pollution studies and forensic science. Relative precision of counting 1% if 104 counts are recorded. Assessment of pollution by radionuclides. 

Glascock, M.D. (1992). Characterization of archaeological ceramics at MURR by neutron activation analysis and multivariate statistics. In Chemical Characterization of Ceramic Pastes in Archaeology, ed. Neff, H., Prehistory Press, Madison, Wisconsin, pp. 11-26. 

The number of protons is unique to the element but most elements can exist with two or more different numbers of neutrons in their nucleus, giving rise to different isotopes of the same element. Some isotopes are stable, but some (numerically the majority) have nuclei which change spontaneously - that is, they are radioactive. Following the discovery of naturally radioactive isotopes around 1900 (see Section 10.3) it was soon found that many elements could be artificially induced to become radioactive by irradiating with neutrons (activation analysis). This observation led to the development of a precise and sensitive method for chemical analysis. 

Bishop, R. L. and Blackman, M. J. (2002). Instrumental neutron activation analysis of archaeological ceramics scale and interpretation. Accounts of Chemical Research 35 603-610. 

Descantes, C., Neff, H., Glascock, M. D., and Dickinson, W. R. (2001). Chemical characterization of Micronesian ceramics through instrumental neutron activation analysis a preliminary provenance study. Journal of Archaeological Science 28 1185-1190. 

Mommsen, H., Bier, T., and Hein, A. (2002). A complete chemical grouping of the Berkeley neutron activation analysis data on Mycenaean pottery. Journal of Archaeological Science 29 613-637. 

Moreau, J.-F. and Hancock, R. G. V. (1996). Chrono-cultural technique based on the instrumental neutron activation analysis of copper-based artifacts from the contact period of northeastern North America. In Archaeological Chemistry organic, inorganic and biochemical analysis, ed. Orna, M. V., ACS Symposium Series 625, Washington, DC, American Chemical Society, pp. 64-82. 

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