AN INFRARED BAND SYSTEM OF THE $C_{2}$ MOLECULE

Abstract

A new band system of the $C_{2}$ molecule has recently been $found^{1}$ in emission from a king-type carbon furnace and has been investigated with a high resolution infrared grating spectrometer. Four sequences of bands have been observed; the R-heads of the strongest bands in each sequence are at 5656.2, 7103.0, 4040.1 and $8526.1 cm^{-1}$ in order of decreasing intensity. The bands have triplet P, Q, R structures and have been assigned to a $^{3}\Sigma^{-}_{g}-^{3}\pi_{u}$ transition of the $C_{2}$ molecule. The lower state rotational and vibrational constants agree well with those derived from the Swan bands for the X $^{3}\pi$ state. The molecular constants of the $^{3}\Sigma^{-}_{g}$ state will be discussed.