Overtone Absorption Bands of Gaseous HF

With a 21-foot grating, the structure of the 3←0 and 4←0 vibration-rotation absorption bands of gaseous HF was observed and the lines measured. The vibrational constants of the molecules are, using also Imes' measurements of the 1←0 band: ${\omega }_e=4141.305\mathrm{}$, $x_e{\omega }_e=90.866\mathrm{}$, $y_e{\omega }_e=0.921\mathrm{}$. These constants do not permit evaluation of the energy of dissociation, but the simple Birge formula gives rough agreement. Rotational constants are compared with those obtained from the fundamental band and agree, in general, satisfactorily. No evidence of associated molecules is observed in the overtone bands.