Broadening and shift of thallium nP1/2,3/2 states (n = 6-10) perturbed by noble gas

Impact broadening and shift of the transitions Tl 6P1/2-nP1/2,3/2 (n = 7, 9, 10) and 6P3/2-9P1/2,3/2 are measured by high resolution Doppler-free two-photon spectroscopy. For excited states with small principal quantum numbers the results are in accord with values obtained from C6-C8-C12 potentials calculated semiempirically. For intermediate principal quantum numbers the experiments show that the elastic scattering of the valence electron at the noble gas atom must be considered additionally. The experimental shift rates of P1/2 states are found to be larger than of P3/2 states. Furthermore, the line shifts of the one- and two-photon transitions concerning the 6P1/2, 6P3/2, 9P1/2, 9P3/2, 7S1/2 states show that the contribution of the lower level of the transition must be considered too. (orig.)