Precision measurements of quantum defects in the nP3/2 Rydberg states of 85Rb

Rydberg states are used in our one atom Maser experiment because they offer a large dipole moment and couple strongly to low numbers of microwave photons in a high-Q cavity. Here, we report the absolute frequencies of the P3/2 states for principal quantum numbers n = 36-63. These measurements were made with a three step laser excitation scheme. A wavemeter was calibrated against a frequency comb to provide accurate absolute frequency measurements over the entire range, reducing the measurement uncertainty to 1 MHz. We compare the spectroscopic results with known frequency measurements as a test of measurement accuracy.