| IR SPECTROSCOPY AT THE CANADIAN LIGHT SOURCE: THE $\nu_{11}$ FUNDAMENTAL AND $\nu_{16} + \nu_{18}$ - $\nu_{18}$ HOT BAND OF TRANS-ACROLEIN (2008) | |||||||||
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| Author Institution: Centre for Laser, Atomic and Molecular Sciences (CLAMS), Department of Physics, University of New Brunswick, Saint John, NB, Canada E2L 4L5; CLAMS, Department of Physics, University of New Brunswick, Fredericton, NB, Canada E3B 5A3; Steacie Institute for Molecular Sciences, National Research Council, Ottawa, ON, Canada K1A 0R6; Canadian Light Source, 101 Perimeter Road, University of Saskatchewan, Saskatoon, SK, Canada S7N 0X4. The $\nu_{11}$ fundamental and the $\nu_{16} + \nu_{18}$ - $\nu_{18}$ hot band have been identified in the high-resolution Fourier transform spectrum of trans-acrolein (CH$_2$=CH-CH=O) recorded in the 10-$\mu$m region on the Far-Infrared beamline of the Canadian Light Source synchrotron in Saskatoon. The two bands are centered at 912 cm$^{-1}$ and 957 cm$^{-1}$, respectively, with the excited $\nu_{11}$ state corresponding to the $A^{\prime}$ in-plane CH$_2$-rocking mode and the $\nu_{16}\ + \nu_{18}$ state to the combination of the $A^{\prime\prime}$ out-of-plane CH$_2$ rock with the low-frequency (158 cm$^{-1}$) $A^{\prime\prime}$ C-C torsional mode.This extends our previous work on the $\nu_{14}$ and $\nu_{16}$ fundamentals centered at 993 and 959 cm$^{-1}$, leaving only the $\nu_{15}$ mode now to be assigned at high resolution in the 10-$\mu$m spectral region for this important atmospheric pollutant. The $\nu_{11}$ band is type $a/b$ and the $\nu_{16} + \nu_{18}$ - $\nu_{18}$ hot band is $c$-type, so that assignments could be confirmed by lower-state combination differences. The assigned transitions have been fitted to a Watson asymmetric rotor Hamiltonian, and molecular parameters for both states will be reported. | |||||||||
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