Measurement of the hyperfine coupling constants and absolute energies of the 8p ²P_1/2 and 8p 2P_3/2 levels in atomic cesium

We report measurements of the hyperfine coupling constant for the 8p ²P_1/2 level of atomic cesium, ¹³³Cs, with a relative uncertainty of ∼0.019%. Our result is A = 42.933 (8) MHz, ten times more precise than the previous best measurement, and in good agreement with recent theoretical results. We also examine the hyperfine structure of the 8p ₂P^3/2 level, and derive new values for the energies of the 8p ²P_1/2 and 8p ²P_3/2 levels of cesium.