VUV absorption and its relation to the effects of ionizing corpuscular radiation

Elements of the physics of photoabsorption as well as of energy transfer from fast charged particles are discussed. Among the key notions there are oscillator-strength spectra, quantum yields, and action spectra. Throughout the discussion, emphasis is put on the important role of soft X-rays and VUV light as obtained from a synchrotron radiation source in the understanding of actions of ionizing radiations in general.