AN ANALYSIS OF THE ROTATIONAL STRUCTURE IN THE $C^{1}\pi - X ^{1}\Sigma^{+}$ SYSTEM OF GAF

Abstract

The emission and absorption spectra of CaF have been examined by $Barrow and co-workers.^{1,2}$ Their studies, as well as studies of the microwave $spectrum^{3}$, show that the ground state is $X ^{1}\Sigma^{+}$. There is a $^{3}\pi - ^{1}\Sigma^{+}$ transition near $3000 \AA$ and a $^{1}\pi - ^{1}\Sigma^{+}$ transition near $2100 \AA$. The present paper deals with the rotational analysis of this $C ^{1}\pi - X ^{1}\Sigma^{+}$ system. Barrow et al obtained estimates of the upper state rotational constants from measurements of the P and Q or Q and R head separations in this system. The existence of the Q heads and the presence of $^{69}Ga$ and $^{71}Ga$ in a natural abundance of 3:2 also permitted a very good vibrational analysis of the system. Our present study of the absorption spectrum yielded resolved rotational structure for the (0-0) band. The rotational constants of the $X^{1}\Sigma^{+}$ state were initially fixed at the values obtained by microwave $studies.^{2}$ The resolved P and R branches were then fitted to yield constants (in $cm^{-1}$) for $v = 0$ of the $C^{1}\Pi$ state of $\nu_{00} = 47 323,24$, $B = 0.3579$, and $D = 7.3 \times 10^{-6}$. Our inability to resolve the Q branch prevented us from obtaining any information regarding lambda-type doubling in the upper state. Efforts are currently being made to obtain the spectrum at somewhat higher resolution and extend the rotational analysis to other bands.