Coherence effects in cold cesium atoms

We have studied a ladder and a Lambda system on cold Cesium atoms released from a magneto optical trap. Probe absorption spectra have been satisfactor ily interpreted in terms of a non degenerate three level model at low pump power. At higher power a sum of non interacting three level systems is adeq uate to predict line positions. An experimental test for a sum rule in nonl inear optics is presented and a novel type of dark trap that relies on elec tromagnetically induced transparency for a velocity selective storage in th e dark state is demonstrated.