Tensor Polarizabilities of Sodium Rydberg States

We have used a time-domain spectroscopy technique to measure transitions between fine structure levels of Na Rydberg d and p states in a static electric field. Transitions are driven by delayed pairs of intense sub-nanosecond half-cycle electric field pulses. With these measurements we have determined the fine-structure splittings and tensor polarizabilities of the $n^*$d states for n = 15 to 24, and the $n^*$p states from n = 25 to 32. The results are more than an order of magnitude more accurate than earlier measurements of these quantities.