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.

Squeezed Coherent States in Double Optical Resonance

In this work, we consider a “Λ-type” three-level system where the first transition is driven by a radiation field initially prepared in a squeezed coherent state, while the second one by a weak probe field. If the squeezed field is sufficiently strong to cause Stark splitting of the states it connects, such a splitting can be monitored through the population of the probe state, a scheme also known as “double optical resonance”. Our results deviate from the well-studied case of coherent driving indicating that the splitting profile shows great sensitivity to the value of the squeezing parameter, as well as its phase difference from the complex displacement parameter. The theory is cast in terms of the resolvent operator where both the atom and the radiation field are treated quantum mechanically, while the effects of squeezing are obtained by appropriate averaging over the photon number distribution of the squeezed coherent state.