Efficient four-wave mixing near vibrationai resonances in ozone

Generation of the sum frequency 2ν₁ + ν₂ by vibrational–rotational transitions of molecules in the gaseous phase was achieved for the first time. The pump sources were a CO₂ laser and the nonlinear medium was ozone. A high conversion efficiency, of the order of 0.1% on the energy scale, was attained.