I am involved in the study of intense, ultrashort laser interactions with atoms, ions and molecules. Current technology now makes it possible to generate laser pulses which have durations of a few femtoseconds. For these brief periods the intensity of the light can be a billion billion times brighter than the Sun. I am involved in the study of how atoms are ionized and molecules broken up under these conditions. Recent areas of interest include double ionization of negative ions and preparation of molecular ions in an ion trap prior to irradiation. Selected publications
Suppression of Multiple Ionization of Atomic Ions in Intense, Ultrafast Laser Pulses - Physical Review Letters, 88, 233001 (2002)
Evidence for Re-scattering in Intense, Femtosecond Laser Interactions with a Negative Ion - Physical Review Letters, 93, 223001 (2004)
High harmonic generation by halogen anions and noble gas atoms in a laser field - Journal of Physics B, 38, 1867-1880 (2005)
I have also been involved in the development of a final undergraduate course “Physics in Medicine”, which is run with the assistance of the Northern Ireland Medical Physics Agency. This collaboration has led to the development of joint research projects. Of particular interest is a project into Monte-Carlo modelling of Positron Emission Tomography (PET) to assist in the work of the Northern Ireland PET Institute at the Royal Victoria Hospital.
Dr. Greenwood is a Senior Lecturer in the Centre for Plasma Physics. He obtained a First Class BA in Physics from Keble College, Oxford University in 1991 followed by a Ph.D. entitled "Elastic and Inelastic Scattering of Electrons from Ions" from Queen's University Belfast in 1995. He was involved in laboratory astrophysics as a research associate at NASA's Jet Propulsion Laboratory, Caltech from 1997-99 before returning to Queen's as a Lecturer. He is currently developing a research group which uses ultrashort laser pulses for probing the behaviour of atoms, ions and molecules in intense laser fields - www.ultrafastbelfast.co.uk.
Honours include a Postgradute Distinction Award from the Department of Education (NI) and a National Research Associateship from the National Academy of Sciences (USA). He has held officer positions on IoP group and branch committees for a number of years. His innovative experimental work has merited a number of invited talks at international conferences in recent years, e.g. American Geophysical Union (2001), International Conference on the Photonic, Electronic and Atomic Collisions (2003), International Conference of Multi-photon Physics (2008).