Picosecond Scale Timing of Photoelectrons generated using Synchrotron Light

Instrument development is key in opening new possibilities for research studies of atoms, molecules and materials.  Many modern experimental measurements utilise pulsed light sources such as lasers, synchrotrons and free electron lasers to excite matter. Though time resolved detection systems down to the 300 femtosecond regime are commercially available for photon detection, no systems are available for electron detection in the sub-250 picosecond regime.

The project involves the continuing development and use of an electron Time Resolved Emission Detector (eTRED), the conceptual basis of which was invented at UWA in 2004 and first implemented in a synchrotron light ionisation experiment at Sincrotrone Trieste, Italy in late 2006.  In the early versions of eTRED only electrons with kinetic energies above ~30eV could be studied in the time domain.  A major redesign of the apparatus in 2008 led to the capability to explore time resolved electron emission for >1.5 eV electrons.  This opened the window to explore photo-dissociative molecular states which lead to atomic autoionisation on picosecond and longer timescales.  An example of the type of data recorded using eTRED in O2 is shown in figure 1.

The project will explore the adequacy of the current design of eTRED and it’s use at synchrotron light sources both as a method to measure “slow” autoionisation and as a potential time-resolved diagnostic tool.  In addition the conceptual basis of eTRED will be adapted to provide very short electron injection pulses to a low energy electrostatic storage ring developed collaboratively between UWA and the University of Windsor, Canada.  The style of storage ring, with orbital circumference ~65cm, is shown in figure 2.

Collaborator/s

  • Dr Kevin Prince, Sincrotrone Trieste