Abstract

Rarely ever has there been a period in atomic photoionization studies that the researcher has not felt a keen need for a greater photon flux, for a greater brilliance and for a higher energy resolution. This still holds true whether we concentrate on the very low photon energy region from 5 to 20 eV, the moderate energy region from 20 to 100 eV or the more energetic photons above 100 eV. However, at this juncture, photon sources are expected to become available in the near future which promise to deliver a very high flux of narrow-band photons with a small divergence into a very small area. This combination of parameters amounts to a high spectral brilliance, which is 18 2 predicted to be 10 photons/s(mm·mr)² 0.001% BW at the sample target from 1 to a few hundred eV for a free-electron laser (FEL) photon source. Which problems will sources of this or similar performance allow us to solve?

© 1988 Optical Society of America