Nuclear chemistry
The nuclear chemistry, also called nuclear chemistry, radiochemistry is like the part of the chemical, radioactive substances has as its object. In particular, it deals with the technical implementation of analysis and synthesis in compliance with the radiation protection and often tight time schedule. Application areas include basic research, industrial production, medical diagnostics and therapy (see nuclear medicine) and environmental analysis.
History
Historically, there were chemists who studied first either naturally occurring alpha - decay series (starting from the radioactive Th and U isotopes ) or induced (core physical) nuclear reactions. The transformations of elements ( transmutation, the age-old dream of the alchemists ) occurring could be studied only with sophisticated chemical analysis, especially since the reaction products are often found only in minimal amounts. As examples, the separation of radium and polonium from pitchblende by the chemist Marie Curie and the discovery of nuclear fission by the chemist Otto Hahn and Fritz Strassmann be mentioned.
Nuclear chemistry basic research
Decay series
When nuclear decay of a nuclide often there is no stable decay product, but also a radioactive nuclide. This means that even, a mixture of several elements of an isotopically pure element with time. The of such a mixture outgoing radiation is naturally more difficult to identify than that of a single element. By a chemical separation of the elements from each other, then the elements can be identified by their radiation. Also can thereby clarify the reaction mechanism, ie the order in which carried out the various decay modes. The result is a decay chain. The nuclear chemistry thus enables the assignment of radiation at a given nuclide.
External influences on half-life
In the case of radioactive decay by electron capture there are measurable effects of external conditions such as physical state, pressure or chemical bonding to the lifetime of radioactive atoms. The reason is that in the specific case of electron depends on the decay rate of the spatial distribution of electrons in the innermost shell atom. These in turn are influenced by the external shells which provide the chemical bond. A discussed since the late 40's case, the EC -decay of Be-7 to Li -7 (see Segrè and Hensley ). T. Ohtsuki and colleagues examined the half-life of radioactive Be-7 on the one hand and on the other metal loading in C60 cages ( Buckminsterfullerene ). They found the half-lives of 52.68 ± 0.05 days ( metal) and 53.12 ± 0.05 days ( C60), ie a difference of 0.83 %.
Continuation of the periodic table
For the elements with atomic numbers greater than about 100 could occur in the periodic table by quantum mechanical effects rearrangements. It is therefore a current research topic of nuclear chemistry to determine the chemical properties of the heaviest elements synthesized so far. This physico- chemical experiments have to be carried out partly with only one atom. The heaviest so far examined elements ( Dubnium, seaborgium, Bohrium ) show no fundamental changes to their homologues ( Ta, W, Re).