Absorption of DF laser radiation by propane and butane

Strong absorption bands exist in propane, n-butane, and isobutane in the 3.8 micrometer DF (deuterium flouride) laser spectral output region. Spectral scans of pure atmospheres of these gases were made using a spectrophotometer to obtain moderate resolution data. Long-path absorption cell measurements were made using five DF laser output wavelengths to obtain high resolution data for the three gases. The absorption cell concentrations of the gases used, 150 to 450 mtorr, were buffered to 760 torr with nitrogen. Results show that DF radiation is attenuated by a few percent per km when propane or butane concentrations are a few ppm.