Absorption by an aromatic group of a photon energetic enough to break bonds or eject electrons is important in damage to biomacromolecules (e.g., tyrosine, tryptophan or DNA bases) but also in the photophysics of dyes, nanolithography and polymer cross linking.  Polar environments stabilize charge separated states but the energetic thresholds for ionization processes taking over from more standard photochemistry (radiationless decay, bond breaking) are usually not known and mechanisms by which charges are separated are nearly always unclear.  We have used a combination of water jet photoemission and femtosecond electronic spectroscopy of building block aromatics like phenol and nucleosides to address both these outstanding issues.  Insights from such experiments are helpful in understanding ultraviolet damage and in designing organic materials for exciton transport and charge separation in solar photovoltaic systems.

Photoionization, photodissociation, or ultrafast relaxation? How the aqueous aromatic chromophores of life deal with a UV photon

244th National Meeting (2012)

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