Electromagnetically induced absorption

A large increase in atomic absorption due to coherent interaction with reso nant radiation is predicted for a closed transition between two degenerate atomic levels verifying 0<F-g<F-e (F-g and F-e are the total angular moment um of the ground and the excited levels, respectively). in good agreement w ith the theoretical prediction, a total absorption enhancement by a factor 1.7 was obtained on the D-2 line of Rb-85 in a vapor cell experiment.