Laser double optical resonance excitation-ionization of Mo with optogalvanic detection

We report on measurements of resonant three-step, two-colour ionization of atomic molybdenum, using a hollow cathode lamp (HCL) with optogalvanic detection. Wavelength scans were made for two specific transitions involved in the ionization pathways under investigation, namely 4d5(6S)5s 7S3 - 4d5(6S)5p 7P4 and 4d5(6S)5p 7P4 - 4d5(6S)6d 7D5.So-called ‘slow’ and ‘fast’ optogalvanic signals were observed for each pathway. Results confirm the HCL as a cost effective spectroscopic investigation tool. In particular its use in the optogalvanic mode of operation allows one to precisely, easily and reliably tune the wavelength of one or more lasers to resonances of interest for experiments in the general domain of atomic vapour laser isotope selection (AVLIS). The measurements are closely related to the Selective Production of Exotic Species (SPES) project at the ISOL facility and were performed in the recently established laser laboratory in Legnaro National Laboratories of INFN.