Two-step laser excitation of 5P(3/2)np, nf J=1 and 2 autoionizing Rydberg levels of tin

New experimental data on the even-parity autoionizing Rydberg series in the region between P-2(1/2) and P-2(3/2) fine structure ionic limits of tin us ing a two-step laser excitation scheme in conjunction with an atomic beam a pparatus are presented. The 5p6s P-1(1) (3/2, 1/2), level at 39 257.1 cm(-1 ) was used as an intermediate level to access the levels lying above the fi rst ionization threshold. The upper levels are designated using the jj-coup ling scheme and the following Rydberg series 5pnf(3/2, 7/2)(2) (6 less than or equal to n less than or equal to 34), 5pnf (3/2, 5/2)(2) (6 less than o r equal to n less than or equal to 18), 5pnf (3/2, 5/2)(1)(6 less than or e qual to n less than or equal to 11), 5pnp (3/2, 1/2)(2) (9 less than or equ al to n less than or equal to 37), 5pnp (3/2, 1/2)(1) (9 less than or equal to n less than or equal to 18), 5pnp (3/2, 3/2)(2) (9 less than or equal t o n less than or equal to 27) and 5pnp (3/2, 3/2)(1) (9 less than or equal to n less than or equal to 18) have been detected. The observed spectra are simulated within the framework of the multi-channel quantum defect theory.