A vacuum ultraviolet monochromator has been combined with a mass spectrometer to study photoionization processes between 1570 and 430 A. Monochromatic photons were used to ionize, A, He, Ne, O<sub>2</sub>, N<sub>2</sub>, CO, NO, CO<sub>2</sub>, N<sub>2</sub>O, and NO<sub>2</sub>; and preliminary measurements of ion intensity as a function of photon energy have been obtained for the parent ions together with their fragments. The appearance of ionization and the structure of curves, in which ions per unit photon flux <i>versus</i> λ are plotted, will be related to previously reported energy levels, to photoionization cross sections, and to dissociative photoionization mechanisms.
G. L. WEISSLER, J. A. R. SAMSON, M. OGAWA, and G. R. COOK, "Photoionization Analysis by Mass Spectroscopy," J. Opt. Soc. Am. 49, 338-348 (1959)