Chemoautocollimation of radiation from a cw CO2 laser in ethylene

The formation of a chemoautocollimation light guide of length approximately 4 cm and diameter 150 μm was observed upon focusing radiation from a 35-W cw gas-discharge CO₂ laser into the ethylene flow. The high-intensity laser radiation in the autocollimation channel initiated ethylene pyrolysis leading to the production of acetylene, and resulted in the visualisation of the channel.