Abstract The emission spectrum of a low-pressure diffusion flame of a mixture of SOCl 2 and CHCl 3 burning in potassium vapor includes the (0, 0) band of the A 2 Σ+-X 2 Π system of SH. When CDCl 3 is substituted for CHCl 3 the flames emit the (0, 0) and (0, 1) bands of the AX system of SD. The (0, 1) band has not been observed previously. Together with data from the high-resolution study of the (0, 0) band by Ramsay, analysis of the (0, 1) band permits ...