HIGH RESOLUTION FOURIER TRANSFORM EMISSION SPECTROSCOPY OF THE $\tilde{A}^{2}\Sigma^{+}-\tilde{X}^{2}\Pi$ TRANSITION OF THE ${\rm ICN^{+}}$ ION
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Date
2006
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Publisher
Ohio State University
Abstract
The visible and near infrared emission spectrum in the 480 - 900 nm region of ${\rm ICN^{+}}$ was measured by Fourier transform spectrometer (Bruker IFS 120HR). The ${\rm ICN^{+}}$ was produced by Penning ionization of ICN with metastable He*. The ${\rm ICN^{+}}$ ion has much larger spin-orbit interaction constant ($A=-4343{\rm cm^{-1}}$) than those of the ${\rm ClCN^{+}}(-276{\rm cm^{-1}})$ and the ${\rm BrCN^{+}}(-1477{\rm cm^{-1}})$}, {\it J. Phys. Chem.}, {\bf 89}, 4213-4219, (1985)}. The Renner-Teller effect appears in the $\nu_{2}$ excited state of $\tilde{X}^{2}\Pi$. It is interesting to study the Renner-Teller effect of ${\rm ICN^{+}}$. Eight vibronic bands of the $\tilde{A}^{2}\Sigma^{+}-\tilde{X}^{2}\Pi$ transition (both for the $\Omega=1/2$ and $3/2$ spin components) of ICN$^{+}$ were observed. So far, the rotational analysis was performed for two vibronic bands, $\tilde{A}^{2}\Sigma^{+}(000) -\tilde{X}^{2}\Pi_{3/2}(000)$ and $\tilde{A}^{2}\Sigma^{+}(000) - \mu^{2}\Sigma(010)$. Molecular constants, including the band origin, the effective rotational constant, centrifugal distortion constant and spin-rotation interaction constant, were determined for the $\tilde{A}^{2}\Sigma^{+}$ and $\tilde{X}^{2}\Pi_{3/2}$ states.\\ Due to the Renner-Teller effect, the $\tilde{X}^{2}\Pi(010)$ state was split into four vibronic components, $\mu^{2}\Sigma$, $\kappa^{2}\Sigma$, and $^{2}\Delta_{P}$($P=3/2$ and $P=5/2$). For the $\tilde{A}^{2}\Sigma^{+} - \mu^{2}\Sigma$ band, $P_{1}, P_{2}, R_{1}$ and $R_{2}$-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 $\epsilon$ for the $\tilde{X}^{2}\Pi$ state was determined to be $-$0.197 from the $\Omega$-type doubling constant. The determined Renner parameter $(\epsilon=-0.197)$ was close to that of BrCN$^{+}$($-$0.185). We are now analyzing the spectrum for the $\Omega=1/2$ spin component, $\tilde{A}^{2}\Sigma^{+}(000) -\tilde{X}^{2}\Pi_{1/2}(000)$ and $\tilde{A}^{2}\Sigma^{+}(000) -\kappa^{2}\Sigma(010)$, to study the Renner-Teller effect in more detail.\\
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Author Institution: Department of Chemistry, Faculty of Sciences, Kyushu University,; Fukuoka, 812-8581 JAPAN