Knowledge Bank

The visible and near infrared emission spectrum in the 480 - 900 nm region of $ICN+$ was measured by Fourier transform spectrometer (Bruker IFS 120HR). The $ICN+$ was produced by Penning ionization of ICN with metastable He*. The $ICN+$ ion has much larger spin-orbit interaction constant ($A=-4343cm-1$) than those of the $ClCN+(-276cm-1)$ and the $BrCN+(-1477cm-1)$}, {\it J. Phys. Chem.}, {\bf 89}, 4213-4219, (1985)}. The Renner-Teller effect appears in the $\nu 2$ excited state of $X~2\Pi$. It is interesting to study the Renner-Teller effect of $ICN+$. Eight vibronic bands of the $A~2\Sigma +-X~2\Pi$ transition (both for the $\Omega =1/2$ and $3/2$ spin components) of ICN$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ were observed. So far, the rotational analysis was performed for two vibronic bands, $A~2\Sigma +(000)-X~2\Pi 3/2(000)$ and $A~2\Sigma +(000)-\mu 2\Sigma (010)$. Molecular constants, including the band origin, the effective rotational constant, centrifugal distortion constant and spin-rotation interaction constant, were determined for the $A~2\Sigma +$ and $X~2\Pi 3/2$ states.\ Due to the Renner-Teller effect, the $X~2\Pi (010)$ state was split into four vibronic components, $\mu 2\Sigma$, $\kappa 2\Sigma$, and $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Delta P$($P=3/2$ and $P=5/2$). For the $A~2\Sigma +-\mu 2\Sigma$ band, $P1,P2,R1$ and $R2$-branch were observed. For the $\mu 2\Sigma$ vibronic state, $\Omega$-type doubling constant was determined as well as the rotational constant and centrifugal distortion constant. Renner parameter $ϵ$ for the $X~2\Pi$ state was determined to be $-$0.197 from the $\Omega$-type doubling constant. The determined Renner parameter $(ϵ=-0.197)$ was close to that of BrCN$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$($-$0.185). We are now analyzing the spectrum for the $\Omega =1/2$ spin component, $A~2\Sigma +(000)-X~2\Pi 1/2(000)$ and $A~2\Sigma +(000)-\kappa 2\Sigma (010)$, to study the Renner-Teller effect in more detail.\