Heteroaromatic biomolecules ultrafast spectroscopy in liquids
I propose to determine the complete ""structure-dynamics-function"" picture of the photoinduced processes happening in heteroaromatic bimolecules in solution under ultraviolet (UV) light exposure.
Whilst light induced processes are essential to life (vision and light harvesting processes such as photosynthesis are two prominent examples), they can also be extremely detrimental, as is the case for UV radiation damage of DNA. Nucleobases readily absorb UV light, accessing an electronically excited state and potentially triggering a structural rearrangement, leading to photolesions. Still, these “building blocks” of life present an inherent resistance (""photostability"") to these processes, compared to other classes of molecules. This property, far from being comprehensively understood, is believed to be linked with how efficiently these molecules release the excess energy of the photo-prepared electronically excited state through non-radiative relaxation pathways (conical intersections - CIs).
The location and topography of CIs can be extremely environment-dependent, particularly in a polar solvent like water: it is thus the interplay between solute and solvent that governs the dynamics and, thus, biological function of these molecules.
I propose to perform few-fs resolved deep ultraviolet (DUV) pump - extreme ultraviolet (XUV) probe time resolved photoelectron spectroscopy (TRPES) studies on heteroaromatic biomolecules in solution, with the goal of determining their solvent dependent structural changes (location of the relevant CIs) and the early stages (first tens of fs) of the related ultrafast relaxation pathways.
A deeper understanding of the relationship between the structure, dynamics and function of heteroaromatic biomolecules in solution under UV exposure could have multiple implications, from the more basic improvement of auxiliary protections against UV (e.g. better sunscreens) to more advanced materials- and bio- engineering based on nature mimicking.