R-System of Fluorescence Excitation Spectrum of CS₂ Cooled in a Supersonic Free Jet

R-system of fluorescence excitation spectrum （371—350 nm） of CS₂ cooled in a supersonic free jet is observed. the congestion of bands is eliminated significantly in contract to the corresponding spectrum at room temperature. The vibrational bands are assigned and the rotational structure of some bands are analyzed. the rotational temperature of the molecule in this case is cooled down to 15.6K.