Vibrational spectra of indene. Part 4. Calibration, assignment, and ideal-gas thermodynamics
| Autor: | T.D Klots |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Chemistry
Infrared Analytical chemistry Molecular physics Potential energy Atomic and Molecular Physics and Optics Hot band Ideal gas Spectral line Analytical Chemistry chemistry.chemical_compound symbols.namesake Normal mode symbols Physics::Chemical Physics Indene Raman spectroscopy Instrumentation Spectroscopy |
| Zdroj: | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 51:2307-2324 |
| ISSN: | 1386-1425 |
| DOI: | 10.1016/0584-8539(95)01431-4 |
| Popis: | The vibrational spectra of indene have been examined in the vapor and the liquid state using infrared and Raman spectroscopy. Wavenumbers of the liquid spectra are measured to 0.1 cm −1 to re-examine the potential of indene as a calibration molecule. An assignment for its normal modes of vibration is made considering vapor band shapes, polarization ratios and calculated frequencies from a scaling procedure of the indene AM1 force field. An AM1 analysis of the cyclopentadiene vibrations is performed to obtain the scale factors for the constituent five-membered ring. The root-mean standard deviation of the calculated relative to the observed frequencies is 11 cm −1 for the planar modes and 16 cm −1 for the nonplanar modes. The potential energy distribution for the nonplanar modes from a refinement calculation is discussed. Ideal-gas thermodynamic functions are evaluated using the vapor phase vibrational wavenumbers and the previously reported moments-of-inertia. The spectroscopic ideal-gas entropy exceeds that determined from calorimetry by ≈ 0.95 R (R = 8.31451 J K −1 mol −1 ) from 300 to 500 K, indicating that the crystal most probably contains some residual disorder at 0 K. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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