Abstract
The main aim of the research presented in this dissertation is to develop a novel imaging mass spectrometry technique that uses molecular desorption induced by heavy ions accelerated to kinetic energies in the MeV/u regime. Upon impact with a sample, heavy ions accelerated above the Bohr velocity deposit their energy predominantly through electronic stopping and this has been shown to produce high sputtering yields from an insulating sample’s surface. This interaction has been traditionally called electronic sputtering and was first put to analytical use many decades ago by a technique called Plasma Desorption Mass Spectrometry (PDMS). Despite its inability to provide spatially resolved measurements, PDMS became a popular way to analyse biomolecular samples until other techniques, such as matrix-assisted laser desorption/ionisation (MALDI), became readily available. There are many ion beam analysis (IBA) facilities currently operating throughout the world dedicated to accelerating and focusing ion beams with the required kinetic energy to induce electronic sputtering, but until this work there has not been any attempt to develop a time-of-flight secondary ion mass spectrometry (ToF-SIMS) technique that makes use of a scanning proton microprobe facility. This research, therefore, has been performed at the Surrey Ion Beam Centre to explore the benefits of exploiting electronic sputtering in imaging mass spectrometry studies using existing IBA technology and techniques. Due to its initial success, this novel imaging mass spectrometry technique has recently been recognised as "MeV-SIMS" by the international scientific community. As will be presented in the final chapter, because MeV primary ions can be focused through thin exit windows to analyse a sample without the need for a vacuum chamber, MeV-SIMS has recently been developed into a fully ambient pressure technique.