Accessing active sites of molecular proton dynamics The unceasing impact of intense sunlight on earth constitutes a continuous source of energy fueling countless natural processes. On a molecular level the energy contained in the electromagnetic radiation is transferred through photochemical processes into chemical or thermal energy. In the course of such processes photo excitations promote molecules into thermally inaccessible excited states. This induces adaptations of their molecular geometry according to the properties of the excited state. Decay processes towards energetically lower lying states in transient molecular geometries result in the formation of excited state relaxation pathways. The photo chemical relaxation mechanisms depend on the studied system itself the interactions with its chemical environment and the character of the involved states. This thesis focuses on systems in which photo induced deprotonation processes occur at specific atomic sites. To detect these excited state proton dynamics at the affected atoms a local probe of molecular electronic structure …