Ultrafine particle formation by resonant laser excitation of potassium molecules

In a heat pipe oven containing potassium and a noble gas we have observed a large production of metallic potassium particles upon resonant laser excitation of the K₂ molecules. This is a new method for particle production, based on the strong local heating of the vapor due to the high absorption rate of the laser light. As a consequence of the disequilibrium caused at the gas/vapour boundary by this heating, a supersaturated region is created where the vapor condenses and produces ultrafine particles.