“…This measurement is important to many diverse areas such as heterogeneous catalysis (active site (1) and support characterization (2)) and lunar geochemistry (accurate prediction of the chemical composition of lunar rocks based on limited analyses (3)). As a first step, we measured the energy dependence of the Ti, Cr, and Mn 3p subshell photoionization cross sections from 90 to 200 eV by using synchrotron radiation to find the photon energy (and other experimental conditions) that would maximize the sensitivity (4). From the measured 3p cross sections and an evaluation of the light flux available from the monochromator at a given resolution, it was determined that photon energies of 90,100, and 105 eV for Ti, Cr, and Mn, respectively, would maximize signal levels.…”