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Photoionization: Overview

Photoionization occurs when the absorption of an ultraviolet or X-ray photon by a molecule causes ejection of an electron. It is, quite literally, a universal natural phenomenon, that generates chemically reactive ions (electrically charged molecules). More background and context...

The emitted photoelectrons also carry information. Traditional studies examined just their energy but more recent investigations of photoionization dynamics examine many more variables and reveal far richer detail of electron-electron and electron-nuclei interactions within the molecule.

Research Interests

MPiRD research primarily focusses on fundamental aspects of photoionization — of systems ranging from diatomics to small bio-molecules and small clusters — but the impetus and motivation for developing new areas of interest can be drawn from very real, practical applications, such as breath analysis. We actively develop both theory and experiment with an emphasis on measuring angular distributions and vector properties.

Alignment and Orientation

Better understanding of photoionization dynamics comes from the development of ways to examine molecules that are held in a fixed spatial orientation. Conversely, photoionization can be exploited to create and/or probe molecular alignment in chemical reactions.

PhotoElectron Circular Dichroism (PECD)

Recently, we predicted a novel angular asymmetry in the photoionization of chiral molecules using circularly polarised VUV and soft X-ray radiation. The experimental work stimulated by these calculations – using natural product odour molecules etc. – confirms that this is a massive chiral effect that provides a sensitive probe for absolute configuration, and reveals it is also unexpectedly sensitive to conformation (shape) in small bio-molecules.

More about MPiRD research...


View movies showing animated calculations of:
  • Photoionization from fixed-in-space (oriented) molecules
  • Shape resonances in photoelectron wavefunctions
  • Shape resonances in photoelectron angular distributions
  • Cooper minima

Interactive Tutorials

Explore simple quantum mechanical principles and photoionization dynamics (needs Java-enabled browser).