High-precision measurement of lifetimes and collisional decay parameters in Ca D1 states using the two-photon Hanle effect

We report high-precision measurements of the lifetimes and collisional decay parameters of the (4p2) 1D and (4s5d) 1D states of atomic calcium using the two-photon Hanle effect. Modification of the excited-state decay rates due to saturation of the two-photon transition is clearly observed. Spontaneous-emission rates of the possible dipole transitions from these states are deduced through branching-ratio measurements and compared with theory. The (4s4d) 1D lifetime is determined through observation of its exponential decay.