Plasma, often called the fourth state of matter, is characterised by partial or total ionisation of gas phase species. A multitude of systems fall within this definition, from natural plasmas like the auroras through to man-made plasmas like those utilised in plasma arc welding. All forms of plasma contain free electrons and ions and it is these that give plasma interesting and useful chemistry. Within The Ritchie Group our plasma research focuses on two main varieties of man-made plasma: low pressure industrial plasma and atmospheric pressure plasma jets. Low pressure industrial plasmas are used to manufacture semi-conducting oxide and nitride layers. These plasmas are confined to a plasma chamber and contain a wide range of excited and atomic species, giving these systems complex and interesting chemistry. Atmospheric pressure plasma jets (APPJ's) are formed by applying a strong alternating field to a flow of gas. The resulting plasma jet has been found to have sterilising properties and this has resulted in growing use of these systems in medical settings.