Direct observation of the ultrafast dynamics of ionized biomolecules in aqueous solution

Abstract

In biological systems, biomolecules such as amino acids play important roles as building blocks of proteins and precursors to several neurotransmitters. The amino acids and their radicals are involved in several biological processes, and they are therefore of interest. The development of ultrashort pulses allows scientists to study and elucidate many of these ultrafast processes. In this work, I will present the ultrafast dynamics of photoionized or photodetached biomolecules in aqueous solution by utilizing sub-6 fs laser pulses in transient absorption pump-probe spectroscopy. I will present the ultrafast vibrational wave packet dynamics of photodetached aqueous tyrosinate dianion, tryptophan anion and phenylalaninate anion. In addition, the study on the photodetached phenylalaninate anion aims to understand the photodissociation behavior of the phenylalanine radical upon photodetached. Moreover, the study on ionized phenol, the sidechain of tyrosine, investigates the ultrafast proton transfer dynamics of the phenol radical cation in aqueous solution. Our experimental results are complemented with density functional theory (DFT) calculations.