A collimated, cold and supersonic molecular beam of sodium molecule
(Na2) was constructed to study the rotational constants of sodium molecule.By
using the laser induced fluoresence technique, the fluorescence signals were
detected. The obtained spectral lines were highly resolved by using the Auto-
Scan-ring-dye laser system. The Doppler width of the spectral lines were very
narrow i.e. FWHM was very small value down to 10-3cm-1. The results of the
rotational constants of Na2 molecules were fitted by using the least square
fitting method. In addition the rotational temperature of Na2 molecules was
determined to be 18K.