Experimental and theoretical studies into molecular photodynamics on the ultrafast dynamics

点击翻译按钮获取中文摘要

Over the last few decades, developments in sub-picosecond laser technologies, especially at free-electron laser (FEL) facilities, have allowed for an increasingly accessible means of exploring the ultrafast photo-initiated dynamics of various small molecules in the gas-phase. In particular, utilising ultrafast lasers in pump-probe experiments has led to the concept of a "molecular movie", which encompasses following molecular dynamics on timescales as short as a few femtoseconds. Through developing comprehensive quantum molecular structure and trajectory theories for such experiments, experimental outcomes of such dynamical experiments are sought to be rationalised. However, the time taken to perform quantum chemical calculations at a desired level of accuracy often scales exponentially with the size and number of degrees of freedom in a chemical system. Hence, developing algorithms which maximise the accuracy of quantum chemical calculations yet which correspondingly minimise the run-time remains an important research theme in theoretical chemistry. Further to this, there often remains the need to synthesise the results of theoretical calculations with experimentally determined parameters for a given experiment so as to allow for a direct comparison between theory and experiment. The aim of this project is to develop and implement existing quantum chemical methods in order to study the ultrafast molecular dynamics of select small chemical systems. Another main focus will be developing a means of using theory and a knowledge of experimental setup to predict experimental parameters which can be measured at experiments to be conducted on such molecules at ultrafast laser facilities. Specifically, integrating theory with the outcomes of a set of experiments called Coulomb explosion imaging (CEI) experiments will be a focus of this work; this is something which has not yet been achieved at a considerable depth of theory. CEI experiments involve the rapid fragmentation of a highly-charged precursor ion; fragments are then detected spatially and temporally according to their mass-to-charge ratios by two-dimensional detector, where the radius of an ion detected within a given time-interval on the detector is indicative of its velocity within the detector plane. This project will also involve taking part in running and acquiring data from CEI experiments at facilities such as the Artemis laser facility in Oxfordshire. This project falls within the EPSRC Physical Sciences Research area.