THE FIRST NEGATIVE (B-X) SYSTEM OF $^{13}C^{18}O^{+}$: PRECISE MOLECULAR CONSTANTS OF ITS $X^{2}\sum^{+}$, $A^{2}\Pi_{1}$ AND $B^{2}\sum^{+}$ STATES

Abstract

The $^{13}C1^{8}O^{+}$ ions were excited in the cathode glow of a hollow-cathode discharge tube and the first negative $(B^{2}\sum^{+} -X^{2}\sum^{+})$ system was recorded in the spectral region 2110-2755 $\AA$. A total of 22 bands with V^{\prime}=0 to 4 and v""=0 to 7 were observed under medium dispersion. The rotational structure of the 13 of these bands were recorded under high resolution on a 3.4 m Jarrell-Ash Ebert grating spectrograph using a 1200 grooves/mm grating in the fifth and sixth orders. The molecular constants derived from the analysis of the individual bands of this system were first merged together by the method of correlated least-squares fit. The resulting constants were then merged with those obtained from our recent studies on the comet-tail $(A^{2}\Pi_{1}-X^{2}\sum^{+})^{1}$ and the Baldet-Johnson $ (B^{2}\sum^{+} -A^{2}\Pi_{1})^{2}$ systems of $^{13}C^{18}O^{+}$, and a precise set of molecular constants for the X, A, and B states was obtained. The vibrational constants for these three states and also the vibrational term values were obtained using the band origin data. The details of the analysis and the results obtained will be presented.