Knowledge Bank

Absorption bands of acetylene in the region 1970 to 2470{\AA} have been photographed in the fourth and fifth orders of a twenty-one-foot grating spectrograph at absorbing paths of 0.007 to 70 meter-atmospheres. The seven progressions of bands found by previous $workers1$ were observed. In each progression the fine structure is essentially the same for all bands. The temperature $dependence1$ of at least one band from each of the progressions has been checked by cooling a one-meter absorption tube with dry ice. In measuring the fine structure special attention has been given to the least overlapped bands of those originating in the lower vibrational state. Their rotational analysis will be discussed.