INFRARED-ULTRAVILET DOUBLE RESONANCE SPECTROSCOPY OF ACETYLENE: UNRAVELLING THE MYSTERIES IN THE $\nu_{CC} + 3\nu_{CH}$ REGION AT 11 600$cm^{-1}$ USING THE CLUSTER/POLYAD MODEL
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Date
1997
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Ohio State University
Abstract
Time-resolved fluorescence-detected infrared-ultraviolet optical double resonance (IR-UV DR) experiments have been. used to obtain detailed measurements of spectroscopic and dynamical processes in the ``$\nu_{CC} + 3\nu_{CH}$^{\prime\prime} region of acetylene ($C_{2}H_{2}$) at 11 $600 cm^{-1}$. The rotational energy transfer (RET) and vibrational energy transfer (RET) and vibrational energy transfer (V-V) kinetic data collected have already been well fit to 3 detailed rate-equation model that incorporates empirical exponential -gap fitting $laws.^{h}$ In order to explain some of the unusual effects observed in this region we now use the cluster/polyad model that has already successfully interpreted the vibrational energy pattern in $C_{2}H_{2}$ up to $12 000 cm^{-1}.^{i}$ Our work emphasises rotational perturbations, after including the rotational l-type resonance interaction. This enables us to identify the intramolecular couplings responsible for enhancement of rotationally-resolved V-V energy transfer between coupled rovibrational levels of the ``$\nu_{CC} + 3\nu_{CH}$^{\prime\prime} manifold. The model also provides qualitative evidence that Coriolis-type perturbations are responsible for other unusual symmetry-breaking phenomena in this region.
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$^{h}$A. P. Milce, H.-D. Barth and B. J. Oty, {J Chem. Phys}. \textbf{100} 2398 (1994) A. P. Milce and B. J. Orr, {J. Chem. Phys}. 104, 6423 (1996), ibid 106 (1997) in peint. $^{i}$M. A. Temsamani and M. Herman, J. Chem Phys \textbf{102}. 6371 (1995); ibid. 105, 1355(1996); M. A. Temsamani, M. Herman, S. A. B. Solina, J.P.O'Brien and R. W. Field, J. Chem. Phys. \textbf{105}, 11357 (1996).
Author Institution: School of Chemistry and Centre for Lasers and Applications, Macquarie University
Author Institution: School of Chemistry and Centre for Lasers and Applications, Macquarie University