Absolute frequency measurement of the 6D(5/2) level of neutral Cs-133 using two-photon spectroscopy

We report absolute frequency measurements on the 6D(5/2) level of neutral Cs-133 using sub-Doppler two-photon spectroscopy. The absolute center-of-gravity energy for the 6D(5/2) level is determined to be 22 631.683 877(6) cm(-1), a factor of 170 times improvement over the previous measurement from 1964 of 22 631.6863(10) cm(-1). This measurement also corrects a 2.4 sigma discrepancy with the previously measured value. The hyperfine coefficients were found to be A = -4.629(14) and B = -0.10(15) MHz, which are consistent with previous results.