Research objectives and content
With the development of laser sources capable of delivering light pulses of 100 femtoseconds or less during the last ten years, a forefront area of research in chemical physics has been to study the forces that govern chemical reactions through measurements of bond breakage and formation in real time. By far most work has been carried out on photodissociation of single molecules in gases and in solution, with very few studies of bimolecular processes due to the difficulty of triggering a collision between separated molecules with femtosecond precision. This fellowship application proposes studies of bimolecular reactions by time- resolved pump-probe femtosecond spectroscopy in which reactant molecules are pre-aligned in close proximity on the surface of a solid crystal. The proposed research programme seeks to study atom-molecule, molecule-molecule and ion-molecule collisions triggered by direct photolytic bond cleavage, ultrafast heating and electron scattering respectively. The ob- jective of these experiments it to determine the reaction mechanism by mapping out the time dependence of the nuclear motions. With input from time-dependent wavepacket calculation, this work aims to achieve a fundamental understanding of bimolecular reactions in terms of the quantum dynamics of the elementary steps that bring about the overall chemical transformation.