Photo induced collisions with laser cooled He* atoms

This paper presents an experimental investigation of cold collisions between metastable helium atoms in an optical trap at 1 mK. Penning (PI) and associative (AI) ionization reactions are distinguished using a mass spectrometer and studied under influence of near resonant laser light. Dramatic enhancement, by more than a factor 15, of the ion rate is observed when the laser is tuned close to resonance. Experimental findings are well-described, on an absolute scale, by model predictions.