Lifetime of the 2P11 and 3P11 states of atomic helium

Abstract

The radiative lifetime of the 2P11 and 3P11 state of atomic helium has been measured by the level-crossing technique. In the experiment, a beam of 2S01 metastable atoms was first produced and then excited to the 2P11 or 3P11 state with resonance radiation. The lifetimes were measured by observing the zero-field level-crossing signals in the detected 584- or 537- fluorescent radiation when these P11 states decayed to the 1S01 ground state. The results are τ(2P11)=(5.57±0.15)×10-10 sec and τ(3P11)=(1.73±0.11)×10-9 sec. These values are in excellent agreement with theory. © 1971 The American Physical Society.