Column density effect in photoionization and photoabsorption spectra

In our effort to measure both the absorption and ionization spectra in a single experimental set-up, we have demonstrated that the column density not only affects strongly the structure profile of an atomic resonance but also alternates significantly the back ground cross sections in an ionization measurement. In addition, we present a procedure that, together with the peak cross sections estimated from the convoluted theoretical spectra for the lowest resonance of the He (1, 0)0 series, could effectively determine the energy resolution and the detailed characteristics of the monochromator (i.e., slit) function of a given light source. PACS: 32.80.Fb; 32.80.Dz; 32.30.Jc