Collisional perturbation of states in atomic ytterbium by helium and neon

Results of an investigation of collisional deexcitation of the metastable 6 s6p P-3(0) state in atomic ytterbium by helium and neon buffer gases are re ported. We find upper limits for the quenching cross sections to be sigma(H e)<13X10(-22) cm(2) and sigma(Ne)<8x10(-22) cm(2). The small cross sections may allow an ytterbium parity nonconservation experiment to be performed i n a vapor cell. We have also measured the pressure broadening and shift of the 6s6p P-3(0)-->6s7s S-3(1) and 6s(2) S-1(0)-->6s6p P-3(1) transitions by helium and neon. [S1050-2947(99)00408-4].