Long-lived CO₂ lasers with distributed heterogeneous catalysis

In a sealed CO₂-N₂-He system with a clean discharge tube the degree of dissociation of the CO₂ is greater than 80% (with no hydrogen present) and laser action cannot be obtained. If platinum is distributed along the discharge tube walls as a discontinuous film it catalyses back-reactions reforming CO₂. The degree of dissociation is then less than 40% and efficient laser action at 10·6 μm is obtained. Using such distributed heterogeneous catalysis a CO₂-N₂-He-Xe laser has operated for more than 3000 h. In this system both hydrogen and deuterium are undesirable additives because they decrease the excitation rate of the upper laser level.