High efficiency resonance ionization of palladium with Ti:sapphire lasers

This work presents the development and testing of highly efficient excitation schemes for resonance ionization of palladium. To achieve the highest ionization efficiencies, a high-power, high repetition rate Ti:sapphire laser system was used and 2-step, 3-step and 4-step schemes were investigated and compared. Starting from different excited steps, the frequencies of the final ionization steps were tuned across the full accessible spectral range of the laser system, revealing several autoionizing Rydberg series, which converge towards the energetically higher lying state $4d^9{}^2{D}_{3/2}$ of the Pd⁺ ion ground state configuration. Through proper choice of these excitation steps, we developed a highly efficient, fully resonant 3-step excitation scheme, which lead to overall efficiencies of $54.3\left(1.4\right)$ % and $59.7\left(2.1\right)$ %, measured at two independent mass separator setups. To our knowledge, these are presently the highest efficiency values ever achieved with a resonance ionization laser ion source. (paper)