OSCILLATOR-STRENGTHS OF THE SR-I PRINCIPAL SERIES

Oscillator strengths of transitions into high-lying Rydberg states of the Sr I principal series have been determined on an absolute scale. B y applying a saturation technique the photoionization cross section at the first ionization threshold was measured to sigma = (12+/-2.5) Mb and was used to calibrate the f-values of the Rydberg transitions Sr I (5s(2))S-1(0)-(5snp)P-1(1)0 for quantum numbers n = 30-60. The result s are compared with recent literature data. In addition, we show photo absorption spectra near threshold with forbidden one-photon transition s from the ground state to excited states of the same parity.