Energy transfer between electronically excited zinc and calcium atoms

A series of experiments have been performed in which zinc atoms carried in a flowing stream of helium are excited to the 4(3P1) state by optical pumping with a XeCl excimer laser. Addition of calcium atoms to the flow results in quenching of the excited zinc atoms. The cross section for this energy transfer process is sigma> or =3 x 10-16 cm2, corresponding to Zn(4 3P/sub J/) quenching in fewer than 10 collisons with calcium atoms. Subsequent to optical excitation of the zinc atoms, emission was observed from both the 4 1P1 and 5 3S1 excited states of calcium. Integration of the intensities of the calcium emissions indicated that excitation of the singlet and triplet manifolds in calcium occurs with comparable probability, suggesting that spin conservation is not a strong constraint in the energy transfer process. Summation of the intensities indicate that the E--E transfer process accounts for most of the quenching of the excited zinc atoms