Photoprotective properties of a eumelanin building block: Ultrafast excited state relaxation dynamics in 5,6-dihydroxyindole

Skin plays the significant role in protection of body from ultraviolet radiation. The protection is primarily done by a type of pigment called eumelanin. Eumelanin chromophores absorb the energy of the radiation, and through internal conversion, dissipate them quickly in the form of heat. The process takes place in femtosecond time scales. A bottom-up approach is used to study the photophysics of eumelanin which focuses on individual building blocks to gather the overall information of the complex system. Time-Resolved Photoelectron Spectroscopy (TRPES) is implemented to understand the underlying excited state relaxation mechanism in 5,6-dihydroxyindole . This method allows to see the associated dynamics interms of photoelectron kinetic energy.