| With the advent of commercially available solid-state laser sources providing short bright pulses, new possibilities opened up for the study of condensed matter. On one hand, the possibility of seperating the excitation step (mostly optical pumping) and the true photoemission process (probe) allows the temporal evolution of the system to be studied in a spectroscopic way in real time. The temporal resolution solely depends on the pulse width of the light pulses, which nowadays can be as short as a few hundreds of attoseconds. Parallel to these efforts, a new technology evolved aiming at increasing the energy resolution of conventional photoelectron spectroscopy experiments. Pulsed narrow-band lasers along with time-of-flight spectrometers for instance can be used to achieve energy resolutions in the sub-meV range, which yet are unavailable for standard light sources like gas discharge lamps and synchrotron sources. Moreover, the low photon energy of lasers increases the probing depth of the surface sensitive technique and allows more bulk-sensitive information to be gathered. I will review these new developments and summarize some new experimental challenges as well as some new aspects in the interpretation of photoelectron spectroscopies. |
|