Knowledge Bank

The laser absorption spectrum of the $TiCl+$ molecular ion was observed for the first time in a hollow cathode discharge. The discharge was driven at 25 KHz at powers in the range of 80- 100 W. Peak currents of 0.5 A occured during the conducting half-cycles. Flowing samples of $TiCl4$ in Ar were discharged. 235 lines of the $\mathrm{<mrow\; data-mjx-texclass="ORD">48</mrow>}Ti35Cl+[17.9]3\Delta -X3\Phi (0,0)$ band and 122 lines of the $\mathrm{<mrow\; data-mjx-texclass="ORD">48</mrow>}Ti37Cl-[17.9]3\Delta -X3\Phi (0,0)$ band were recorded at resolution $0.02cm-1$. This band system was observed previously in the emission spectrum of $TiCl+$ but the electronic assignments for the lower and upper states of the transition are revised here. Rotational constants (in $cm-1$) and internuclear distances $ro$ (in nm) for the [17.9]$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Delta$ (v=0) and $X3\Phi$ (v=0) states of $\mathrm{<mrow\; data-mjx-texclass="ORD">48</mrow>}Ti35Cl-$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">48</mrow>}Ti37Cl+$ are respectively:$$B^{\prime}{0}=0.178692(16), r^{\prime}{0}=0.2160(1),B^{\prime\prime}{0}=0.174212(16), r^{\prime\prime}{0}=0.2188(1)$$$$B^{\prime}{0}=0.173076(18), r^{\prime}{0}=0.2160(1),B^{\prime\prime}{0}=0.168742(18), r^{\prime\prime}{0}=0.2188(1)$$ These results are in excellent agreement with the predictions based on the ligand field theory $modelsb$. The symmetry for the ground state of the $TiCl+$ molecular ion is determined to be $X3\Phi$. Work supported by AFOSR under grant F19628-90-C-025.