Laser-Induced Fluorescence Apparatus for Application in Rarefied Hypersonic Flow Fields. Part III: Rotational Temperature of 0 2

The rotational temperature of O 2-molecules in a hypersonic free jet was investigated by means of the Laser-Induced Predissociative Fluorescence (LIPF) technique using a tunable ArF*-excimer laser. For analyzing the measured spectra a computer code was developed to calculate the Schumann-Runge bands.The spectra characteristics of the bands considering the tuning range of the laser are described. This code predicts the triplet structure of the bands quite well. The measured rotational temperatures agreed with the theoretical ones. The lower detection limit for rarefied conditions was about 1 x 10 15 molecules/cm3.