INFRARED ABSORPTION OF GASEOUS ${c}$-CLCOOH AND ${t}$-CLCOOH RECORDED WITH A STEP-SCAN FOURIER-TRANSFORM SPECTROMETER
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Date
2009
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Ohio State University
Abstract
Two conformers of ClCOOH were produced upon irradiation at 355 nm of a gaseous flowing mixture of Cl$_{2}$, HCOOH, and N$_{2}$. A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient spectra of ClCOOH. Absorption bands with origins at 1808.0 and 1328.5 cm$^{-1}$ are attributed to the C=O stretching and COH bending modes of ${t}$-ClCOOH, respectively; those at 1883.0 and 1284.9 cm$^{-1}$ are assigned as the C=O stretching and COH bending modes of ${c}$-ClCOOH, respectively. These observed vibrational wavenumbers agree with corresponding values for ${t}$-ClCOOH and ${c}$-ClCOOH predicted with B3LYP/aug-cc-pVTZ density-functional theory and the observed rotational contours agree satisfactorily with simulated bands based on predicted rotational parameters. The observed relative intensities indicate that ${t}$-ClCOOH is more stable than ${c}$-ClCOOH by ~3 kJ mol$^{-1}$. A simple kinetic model is employed to account for the production and decay of ClCOOH.
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Author Institution: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan