Knowledge Bank

The emission spectrum of a low-pressure diffusion flame of a mixture of $SOCl2$ and $CHCl3$ burning in potassium vapor includes the $(0,0)$ band of the $A2\Sigma +-X2I$I system of SH. When $CDCl3$ is substituted for $CHCl3$ the flames emit the (0,0) band (0,1) bands of the A-X 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 determination of the vibrational and rotational constants of the ground state of SD. Isotope relations then provide good values for SH. Absence of emission from $v\prime >0$ in both SH and SD is interpreted to mean that both molecules probably are predissociated between $v\prime =0$ and 1.