Two-photon intracavity dye laser spectroscopy of the 4S and 3D term in6, 7Li

Doppler-free two-photon spectroscopy of several states of^{6, 7}Li has been achieved by placing an atomic beam inside the dye laser cavity. The hyperfine structure splitting of the 4S state, the fine structure splitting of the 3D level as well as the isotope shifts of the 2S–4S and 2S-3D transition have been measured, by scanning the single-mode laser frequency and detecting the fluorescence light. In addition, signal detection by three-photon ionization via the resonant 3D state was accomplished.