Lifetime of the 6s6p1P1 level of barium

The lifetime of the first excited singlet P level of barium, 6s6p1P1, has been determined from the width of the zero field level crossing, i.e. the Hanle effect, of the 6s6p1P1 –6s21S0, 5535 Å resonance line. The resonance radiation was produced in a hollow cathode lamp and the scattering atoms by an atomic beam. After taking account of coherence narrowing, the lifetime is determined to be 8.37 ± 0.14 × 10−9 s, in good agreement with other recent work.