Fluorescein, an organic dye sensitive to light and acidity/basicity was adsorbed on the surface of the titania as a probe molecule. The group used a time-resolved surface plasmon resonance (SPR) spectroscopy with a femtosecond pulsed laser. By using femtosecond pulsed laser SPR spectroscopy, the group was able to indirectly observe the proton transfer process from the dye to the titania surface and proved the formation of basic hydroxyl groups. Observation through the UV irradiation time showed that the surface became more basic with OH groups on the surface of the titania which accepts the protons from the fluorescein monoanion. Time-resolved fluorescence probe observation using organic dyes that are sensitive to light and acidity/basicity is a very effective method for observing small light-induced behaviors (proton transfer processes) that occur on solid surfaces in a very short time. The researchers were successful in observing the dianion and monoanion ratio of the fluorescein through the establishment of the SPR spectroscopy method. Professor Nishikiori hopes to continue to contribute to advances in hydrogen production with photocatalytic water splitting with the establishment of this simple method that enables researchers to observe and evaluate the activity of the photocatalysis. Reference: “Observation of Excited State Proton Transfer between the Titania Surface and Dye Molecule by Time-Resolved Fluorescence Spectroscopy” by Hiromasa Nishikiori, Yosuke Kageshima, Nasrin Hooshmand, Mostafa A. El-Sayed and Katsuya Teshima, 30 September 2021, The Journal of Physical Chemistry C.DOI: 10.1021/acs.jpcc.1c05843
