Correlative spectroscopy of f-elements in crystalline rocks

PhD student:

Raj Sarkar

Supervisor:

Dr. Harald Foerstendorf, PD Dr. Moritz Schmidt (HZDR)

Department:

Thermodynamics of Actinides

Duration:

10/2024-09/2027

Description:

The aim of the work is to identify and characterize surface and solution complexes, local precipitations and incorporations for the trivalent f-elements Cm(III), Am(III), Eu(III) (the latter is used as chemical analogue) under varying geochemical conditions directly on pure minerals and on crystalline rocks.

Spectroscopic methods such as time-resolved laser-induced fluorescence spectroscopy (TRLFS) in combination with atomic force microscopy (AFM), Raman or scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDX), as well as autoradiography and sorption batch experiments are used to identify the reactions at the solid-liquid interface. For the experiments, geochemical boundary conditions are defined with values for pH, ionic strength, ligand and/or metal concentration, which are relevant for potential repository sites.

The specifically determined reactions and thermodynamic data make valuable contributions to the understanding of retention processes in the host rock, which in turn play an important role in the assessment of radionuclide migration as part of a long-term safety assessment.

The work is part of the joint project “SPIEG3L” (Spatially resolved spectroscopies for the identification of interfacial processes and species of trivalent lanthanides and actinides), which is funded by the German Federal Ministry of Education and Research under the funding code 02NUK089B.