LIFETIMES AND OSCILLATOR STRENGTHS IN SR I AND CA I SPECTRA

Radiative lifetimes of some highly excited levels in Sr I were measured by zero-field level crossing technique. These levels have been populated using optical excitation starting from the metastable 4 d 5 s1D2 or 5s 5p3P2,1,0 states. The high population of these metastable levels necessary for the experiments was obtained by a discharge in the pure Sr vapour burning in the atomic beam oven. The following lifetimes have been determined (in units of 10-8 sec):τ(5 s 6s3S1)=1.09±0.11, τ(5 s 5 d3D1)=1.67±0.10, τ(5 s4f1F3)=3.43±0.28, τ(4d5 p1D2)=2.19±0.16, τ(5 p23P1)=0.88±0.12, τ(5 p23P2)=0.78-0.10+0.26. These results are compared with lifetimes derived from oscillator strengths given in the literature, and the reliability of different oscillator strengths tables is discussed. A corresponding discussion is given for radiative lifetimes of some levels in Ca I published previously. Good agreement with data derived from arc emission oscillator strengths has been found. Ca lifetimes are fairly well consistent with oscillator strengths calculated with semiempirical scaled Thomas-Fermi-wave functions. © 1969 Springer-Verlag.