Vibronic structure of theNa3ground state by stimulated emission spectroscopy

Abstract
We report the first observation of the high vibronic levels of the Na3 ground state, performed by stimulated emission spectroscopy. The highest cross sections of the process, which uses the C2E’ ’ state as an intermediate state, are obtained for combinations of symmetric stretch and bending modes. These experimental results are of primary importance for the understanding of energy-level structures in systems exhibiting strong vibronic coupling.