Luminescence spectroscopy as versatile probes for chemical diagnostics on the solid–liquid interface

Observation of the chemical properties, such as the composition, distribution, structure, species, and surface reactions of solid materials, has been an indispensable issue in various fields of science and engineering, such as materials chemistry, environmental geochemistry, photochemistry, catalysis, or chemical synthesis. Physicochemical processes in heterogeneous systems involving solid surface interfaces differ from processes in homogeneous media. Physicochemical processes in heterogeneous systems thus require particular attention because of the discontinuity or high free energy of the interfaces. Such processes can be investigated using experimental methods that derive linear or nonlinear responses to external stimuli by a pulsed laser. In this chapter, state-of-the-art laser-based analytical techniques for actinide chemistry at solid–liquid interfaces are reviewed. These techniques range from luminescence spectroscopy for static and dynamic phenomena to surface-sensitive spectroscopy, for example, time-resolved infrared vibrational/luminescence spectroscopy and vibrational sum frequency generation spectroscopy, and subsequent advanced data analyses. The roles of luminescent molecules and complexes as a probe for the interfacial chemistry are discussed along with the relevant photochemical processes, such as energy or electron transfer. Photochemical properties of the f-block elements, especially actinides ions, at solid-liquid interfaces are focused upon because some actinide ions, such as hexavalent uranium and curium, exhibit exotic luminescent and photochemical properties, which would make them versatile probes of photochemistry of solid surfaces.