method and apparatus for selective photo ionization with respect to an isotope using auto ionization transitions

摘要

Apparatus and process for isotopically selective multistep photoionization in which the ionizing step is tuned to produce a specific transition to an excited state above ionization for which the ionization cross-section is substantially greater than for ionization transitions in general. The autoionization transition to an ionized state is made from a highly excited bound state reached in one or two isotopically selective energy jumps from the ground state or other low-lying levels. The isotope shift for the ionization transition is small compared to the bandwidth of the ionization transition and relatively broad band photoionization radiation covering the entire absorption line can be employed. A technique is also shown for identifying the ionization transitions of augmented cross-section.