New spectroscopic data on odd-parity autoionization states of atomic lutetium

A three-color three-step resonance ionization mass spectroscopy technique was explored to investigate the odd-parity autoionization states of atomic lutetium, covering a range from 51,850 to 55,000 cm-1. By applying Fano fitting to the spectral analysis, we successfully identified 98 autoionization states, with 69 of which had never been reported. We also determined the half-width and transition strength for all identified states. Additionally, the lifetime of the excited state at 36,769.25 cm-1 was measured. This work provides the most comprehensive dataset to date on the complex odd-parity autoionization states of atomic lutetium, offering essential insights for enhancing the efficiency of resonant photoionization processes and understanding the atomic autoionization structure of lutetium.