LIFETIMES OF RYDBERG LEVELS IN THE PERTURBED 6SNP P-1,3(1) SERIES OF YBI

Using two methods: (1) three-step excitation and (2) single UV photon excitation in an atomic beam with direct observation of the decay of t he fluorescence light, we have measured the lifetimes of the Rydberg l evels of YbI belonging to the perturbed series 6snp J = 1 levels. The measured values have been interpreted by the multichannel quantum defe ct theory (MQDT).