Biomolecules, Photostability and 1 πσ ∗ States: Linking These with Femtochemistry

Abstract

In an effort to illuminate why nature has chosen a particular set of bio-molecular ‘building-blocks’ for life, a surge of gas phase experiments have recently targeted understanding why key DNA bases, amino acids and their corresponding chromophore subunits, exhibit a resistance to photochemical damage (photostability) following ultraviolet radiation absorption. The research considered in this chapter focuses on the role of dissociative 1 πσ ∗ states in photostable behavior, and in particular H-atom elimination mediated via these states. By probing the timescales for the appearance of these H-atoms using ultrafast lasers coupled to molecular beam methodologies, important information pertaining to the excited state dynamics of these molecules can be obtained. We also discuss how the information gleaned from these studies can be used as a ‘stepping-stone’ for extending this research to larger, more complex biomolecules and, ultimately, more realistic systems in solution.