CN emission in nitrogen afterglow at low temperatures

A simple and fairly inexpensive new technique for qualitative and quantitative measurements of various gas-phase hydrocarbon species in a flowing gas is reported, and the apparatus for its implementation is described. The method is based on C + N chemiluminescent reactions at low temperatures. Detection of extremely low concentrations of hydrocarbon species was demonstrated. The presence of small admixtures of hydrocarbons in the nitrogen working gas increases the intensity of the CN violet band system at 77 K more than ten times with respect to that recorded at room temperature. The intensities of the CN vibrational band system emitted from the cooled part of the flowing nitrogen afterglow are very specific and can be used as a 'fingerprint' for determining trace concentrations of hydrocarbon species. (J.U.) 2 figs., 5 refs