In this book, the work described the extension of photo-induced H-atom detachment measurements on phenol towards identifying the active participation of the 1pis state in the photochemistry of the amino acid tyrosine. To achieve this feat, a step-wise approach was taken in which the complexity of the system was gradually increased towards the target molecule. This body of work thus confirmed that in the case of the amino acid tyrosine, photoexcitation of the chromophore leads, in part, to subsequent dynamics at the chromophore site (O-H). This prompts the question of whether or not this observation can be extended to other amino acids (e.g. tryptophan) and di/tri peptides. The work described in this book therefore is a stepping stone towards extending these measurements from the micro (chromophore) towards the macro (polypeptides) and it remains to be seen whether or not trends in the electronic structure govern the photochemistry of much larger, realistic systems.