Interpretation of Photogenerated Charge Carrier Transfer Dynamics Using Interactive Surface-Molecular System

This study investigates the charge transfer occurring at the surface-molecular system in terms of understanding the mechanism of photoinduced catalytic reaction. We employed a laser-induced desorption and ionization environment to analyze the physicochemical interactions involved in interatomic charge transfer and the behavior of adsorbed molecules, both of which actively occur on the photocatalyst surface. We found that the reactive hydroxyl radical rapidly extracts electrons from the surface, whereas the cogenerated proton promptly protonates the analyte. This synergistic interplay accelerates interfacial charge redistribution, enhances Coulombic repulsion, and thereby governs the efficiency of laser-induced ionization and desorption. To deepen our understanding of how reactive hydroxyl radicals and cogenerated protons drive atomic-scale catalytic reactions, integrated theoretical and experimental analyses were performed. We demonstrated that localized protonation at electrophilic sites significantly enhances analyte desorption efficiency, governed by molecular orbital localization and surface electronic properties. Specifically, matrices with higher conduction-band energies and increased surface charge localization facilitate stronger Coulombic repulsion at the analyte-matrix interface, accelerating ionization and desorption. Our study addresses not only the clarification of the ambiguity of the experimental observations but also qualitative criteria to evaluate the degree of each stacking sequence. We expect that our findings offer fundamental insights into designing optimized photocatalytic surfaces and molecular targets for advanced laser-induced applications.