Laser-Induced Spectroscopy of Actinides – From simple metal systems to species in living cells

Application of laser-induced methods allow the direct determination of uranium speciation at extremely low concentrations. First tunable solid state laser in an actinide chemistry lab was installed in 1993 in Dresden-Rossendorf under Heino Nitsche’s directorship. Later the installation of the first fs-laser system allowed us to study the interaction of organic compounds with actinides.
U(VI) released anthropogenically, e.g. through mining activities, can be accumulated for instance in plants and consequently can enter further parts of the food chain. Uranium as a redox-active heavy metal can cause also various redox imbalances in plant cells.
Recently we have shown that uranium can be taken up by plant cells. Fractionation studies showed that the uranium was present in nearly all cell compartments.
One of the major remaining questions concerns to the ways of uranium uptake. Recently published work proposed that the uranium uptake is influenced by the iron uptake. As it is known that the iron uptake occurs via reduction of the iron(III) into iron(II), we conclude that uranium uptake should also by accompanied by a redox process.
The evaluation of Laser-Induced Photoacoustic Spectra (LIPAS) in the wavelength range 620 nm to 680 nm gave evidence for the formation of both reduced oxidation states in the media studied. The uranium(V) is assigned to an absorption at around 637 nm, while uranium(IV) absorbs light at ~660 nm.