Hyperfine structure of the7d2D3/2level in cesium measured by Doppler-free two-photon spectroscopy

Abstract

We report the measurement of the hyperfine structure in the 7$d$ ${}^{2}{D}_{3/2}$ state of ${}^{133}$Cs isotope by Doppler-free two-photon fluorescence spectroscopy in a gas cell. The hyperfine level separations were measured using a frequency-stabilized Ti:sapphire laser locked to one of the hyperfine transitions and an acousto-optic modulator locked to another hyperfine transition. The frequency separation between various hyperfine levels has been measured with a precision of \ensuremath{\sim}100 kHz. From the measured hyperfine separations of the excited state, we have determined the magnetic dipole coupling constant ($A$) and electric quadrupole coupling constant ($B$) for the 7$d$ ${}^{2}{D}_{3/2}$ state. The determined hyperfine structure constants are $A=7.38$ (0.01) MHz and $B=\ensuremath{-}0.18$ (0.1) MHz. The values measured are found to be in good agreement with the earlier reported results using stepwise excitation process.