Two-step laser spectroscopy of the even-parity Rydberg levels of neutral tin

We report the first measurements of the even-parity J = 1 and 2 levels of neutral tin using a two-step laser excitation technique in conjunction with an atomic beam apparatus. The Rydberg series 5pnp (1/2, 3/2)(2) (11 less than or equal to n less than or equal to 45) and 5pnp (1/2, 3/2)(1) (12 less than or equal to n less than or equal to 18) have been observed converging to the first ionization limit. In addition, five p-levels; 5p8p (3/2, 3/2)(0,1,2) and three f-levels 5p5f (3/2, 5/2)(1,2) and 5p5f (3/2, 7/2)(2) converging tothe second ionization threshold have been identified. The perturbations among the J = 2 levels have been studied using three-channel quantum defect theory.