HIGH RESOLUTION SPECTROSCOPY OF ZrN: THE (0,0) BAND OF THE $A^{2}\Pi - X^{2}\Sigma^{+}$ TRANSITION

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2001

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Ohio State University

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The $A^{2}\Pi - X^{2}\Sigma^{+} (0,0)$ band of ZrN between 5620 and 5890 \AA has been studied using laser induced fluorescence, wavelength resolved fluorescence, and laser polarisation spectroscopy. All the 12 branches expected from a $^{2}\Pi - ^{2}\Sigma$ transition have been observed and assigned. Severe perturbations in the $A ^{2}\Pi_{3/2}$ substate have been found. These perturbations were found at different J values for different isotopes. For $^{90}ZrN$, the perturbations at $J = 4.5$ and 8.5 of the e level and at $J = 8.5$ and 18.5 of the f level of the $\Lambda$-doubling components of the $A^{2}\Pi_{3/2}$ substate. The most probable perturbing state responsible for giving rise to those perturbations is a non-degenerate $^{4}\Sigma^{-}$ state. In addition, other degenerate perturbations found at $J = 39.5, 4.5$ and 56.5 are consistent with a $^{2}\Delta$ state being the perturbing state. The vibrational dependence and the negative sign of the spin-rotation parameter $\gamma$ observed in the ground state could arise from the interaction between the $X^{2}\Sigma^{+}$ with unobserved $^{2}\Pi$ states of open-shell electronic configuration. Least squares fittings have been performed to obtain accurate molecular constants of the $X^{2}\Sigma^{+}$ state.

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Acknowledgement: This work was carried out with support from the Hong Kong Research Grants Council.
Author Institution: The University of Hong Kong; Department of Chemistry, The University of Hong Kong

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