Dynamics of molecular dissociation in ion impact collision

Abstract

This thesis is concerned with the experimental study of the fragmentation dynamics of multiple charged polyatomic molecules using the highly charged ion (HCI) beam. When a highly charged ion interacts with a molecule, the internal structure of the molecule modifies. Molecular ions, generated upon interaction with a different projectile with neutral target molecules, could be formed in a stable, metastable, or unstable electronic state. In the absence of a stable configuration or bound state, the molecular species disintegrates into ionic or neutral fragments and releases energy in the form of kinetic energy of its fragment particles. The mechanisms by which molecules are ionized and dissociated can be studied by detecting the energy and angular distribution of emitted fragments and electrons of the target molecule and other projectiles. This dissertation investigates the fragmentation dynamics of multiply charged polyatomic molecular ions resulting from the impact of both low and high-energy projectile ions on neutral molecules. The present experiments employ a multi-hit time-of-flight coincidence technique to gain insights into the dissociation of molecules with varying symmetries. Two-body and three-body channel are identified for the molecular ions using a coincidence plot. As the final state comprises of same recoils ions detected in coincidence, it becomes difficult to separate events coming from two different mechanisms. Ion-induced fragmentation of three distinct molecules has been explored in the current study using various momentum representations such as Newton diagram and Dalitz plot. The simple classical model approach and the Native frame approach are used to identify the breakup processes. Analyzing the simulated and experimental plots together provides strong evidence for the proposed fragmentation mechanism and deepens our understanding of the underlying physics of the dissociation mechanism. newline newline