2. The Experiments

Energy must be absorbed by a molecule in order for ion-pair dissociation to occur. Synchrotron radiation is ideal for such experiments because it provides a bright, monochromated and tunable energy source across the entire electromagnetic spectrum. Synchrotron radiation sources accelerate electrons at relativistic velocities in a circular orbit using magnets; this takes place in a storage ring, tens of metres in diameter. The accelerating charges emit collimated light tangentially to the orbital path. Collected from the storage ring at a beamline, the light is optically focused into a monochromator prior to entering the experimental end station. The experiments described in Chaps. 3–6 utilised vacuum ultraviolet (VUV) radiation from beamline 3.1 at the UK Daresbury Synchrotron Radiation Source (SRS).