Allowed and spin-forbidden electric dipole transitions in CaI

Energy levels, transition probabilities, and lifetimes have been determined for all levels of the Ca I spectrum up to 3d4p F-1(3)o using the multiconfiguration Hartree-Fock method with lowest-order relativistic effects included through the Breit-Pauli Hamiltonian. The mixing of singlet and triplet configuration states was found to be considerably stronger in 4s5p P-1,3(1)o levels than in 4s4p P-1,3(1)o levels. The near degeneracy of the nonrelativistic 3d4p F-3(o) and D-1(o) term energies, differing by only 39.59 cm(-1) resulted in highly mixed Breit-Pauli levels for 3d4p F-3(2)o and D-1(2)o. Some intercombination transitions from these levels have transition probabilities of magnitude similar to weaker spin-allowed transitions. The fine-tuned transition probability for the 4s4p P-3(1)o-4s4d D-1(2) transition was found to be 1.53x10(3) s(-1), in agreement with a quenching rate observed in a doppler cooling experiment [Binnewies , Phys. Rev. Lett. 87, 123002 (2001)].