摘要:

The principle of activation analysis is that elements can be made radioactive by exposure to radiations such as neutrons, protons, or high-energy photons. Two physical processes, prompt and delayed, are associated with activation. For example, in the reaction between thermal neutrons and sodium the gamma rays are emitted within 10−12sec of the absorption of the neutron. Several analytical techniques, such as X-ray fluorescence spectrometry, utilize prompt radiation, but these will not be discussed here. Activation analysis proper is concerned with the delayed event resulting from the decay of the activated nuclide. Thus in the reaction above, sodium-24 is radioactive and decays with a half-life of 15 hr, giving off characteristic beta and gamma radiation and forming stable24Mg.

ISSN:0007-8980    

DOI:10.1080/10408348108542725

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Molecular emission cavity analysis (MECA)1.2is a flame photometric technique which relies on a cool flame source to generate relatively broadbanded molecular emissions, such as S2and BO2and, therefore, directly opposes the trend towards hotter excitation sources and higher resolution monochromators required by the more conventional analyses based on atomic spectra. In practice, it has been found to be complimentary to atomic spectroscopic analyses, being able to determine elements (e.g., sulfur and nitrogen) having their atomic resonance lines in the vacuum UV region of the spectrum by the formation of molecules which emit in the visible and U.V. The advantages offered by the technique as well as the problems facing it are unique.

ISSN:0007-8980    

DOI:10.1080/10408348108542726

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor