Recently we have used luminescence spectroscopy and microscopy, to provide detailed insight into the fate of U VI O2 2+ in model biogeochemical systems. Due to excitation from molecular orbitals of largely oxygen p-orbital character to non-bonding uranium-centred forbitals, the U VI O2 2+ species is inherently luminescent, circumventing the need for any responsive probe or contrast agent. The strength of luminescence as an analytical technique lies not just in the low threshold for detection and ease/speed of sample preparation, but also in the broad range of qualitative chemical data that can be obtained from the spectral fingerprint and emission lifetime. Combined with microscopy this allows four-dimensional mapping in the form of Fluorescence and Phosphorescence Lifetime Imaging Microscopy (FLIM and PLIM, respectively) in which photoluminescence indicates the location of an analyte on a cellular level while the steady-state emission profile and luminescence lifetime provide data on the local environment of the analyte at a molecular level.