Odd Rydberg spectrum of20NeI: High resolution laser spectroscopy and multichannel quantum defect theory analysis

We have carried out a high resolution study of odd²⁰Ne(ns, nd J=0, 1, 2, 3, 4) Rydberg states, using transverse resonant two photon laser excitation of metastable²⁰Ne(3s, 1s ₅) atoms in a highly collimated beam. Transition energies of more than 500 levels with principal quantum numbers up ton=80 have been determined with an accuracy of better than 100 MHz relative to the metastable level. Energy independent MQDT-parameters have been extracted from fits to the experimental data near the²⁰Ne⁺(² P _3/2)-threshold. The simultaneous analysis of Rydberg series with different total angular momenta provides new insight into the Coulomb and exchange interactions governing the spectrum of neon.