J-dependence of ionization spectra of Gd measured by resonance ionization

In Atomic Vapor Laser Isotope Separation, some specified isotope is selectively excited by tunable lasers which have narrow line width compared with the isotope shift, and the excited isotope is ionized by an ionization laser. In order to ionize the excited isotope effectively, it is necessary to use the autoionization transitions which have large photoionization cross-sections. In this paper, for the purpose of searching the transition which has a large photoionization cross-section, ionization spectra of Gd were measured by 2-wavelength 2-photons resonance ionization method from the excited levels with different total angular momentum J. The ionization scheme which have an excited level with a large J is closely related to the autoionization transition which has a large photoionization cross-section and a narrow spectrum width. (author)