Spiers Memorial Lecture: prospects for photoelectron spectroscopy.

An overview is presented of recent advances in photoelectron spectroscopy, focussing on advances in in situ and time-resolved measurements, and in extending the sampling depth of the technique. The future prospects for each are considered. Progress in the last few years has been remarkable, aided by substantial advances in photon sources, environmental cells and in analyser and detection technology. It is now possible to use the technique at ambient pressures and above, and to routinely probe interfaces buried many tens of nanometres below the surface in a non-destructive way. Our capabilities in time-resolved photoemission of the solid state have extended so far as to enable exploration of the fundamental timescale of the photoemission process itself.