Isotope shift of the 3s 2S [formula omitted] and 3p 2P J levels in 6,7Li

Abstract

Applying the method of resonant Doppler-free 2-photon laser spectroscopy, the isotope shift of the 6.7Li 2S-3P-17S and 2S-2P-3S transitions have been measured with a thermionic detector. Because the residual isotope shift of the 17S level is negligible, the shift of the 3P level could be derived directly from the first transition. Taking into account the level isotope shift of the 2S ground state, as measured recently in our laboratory, the isotope shift of the 3S level was determined from the second transition. Including precise experimental isotope shift data for 2S, 4S and 2P, approximate scaling formulas for the specific mass shift of the nS and nP level series can be given.