| Autor: |
Richard L. Redington, Robert L. Sams |
| Rok vydání: |
2002 |
| Předmět: |
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| Zdroj: |
Chemical Physics. 283:135-151 |
| ISSN: |
0301-0104 |
| DOI: |
10.1016/s0301-0104(02)00614-6 |
| Popis: |
Nitrogen pressure broadening effects are observed on the high resolution ( 0.0025 cm −1 ) FTIR spectrum of gaseous tropolone at 298 K and 32 m of path length. Broadening observations on narrow absorption spikes contribute to understanding of the spectroscopy and dynamics of tropolone in several ways. First, they help to establish a remarkable progression of sharp peaks near 752 cm −1 as a part of the Q branch of the anharmonic ν22 (COH torsion) fundamental. The subband spacings of about 0.005–0.010 cm −1 are too large to be determined by harmonic vibrational differences in the rotational constants alone and are attributed to vibration–contortion–rotation perturbations of the upper state (ν22) energy levels of this anharmonic and relatively large amplitude vibration. Second, the isolated and sharp Q branch spikes near 915 cm −1 allow first estimates to be made for effective composite pressure broadening coefficients of tropolone–N2 collisions. The coefficients for transitions within the Ncon=0 and Ncon=1 contortion states differ from each other. They are relatively small due to the preponderance of high rotational states in their composition. Third, N2 broadening effects on substructure in the Q branch doublet near 754 cm −1 help support the assignment of this doublet to tunneling structure of the ν37 fundamental (contortion or incipient skeletal tunneling). The observed doublet components appear as perturbatively IR enhanced three and five peak fragments of weak longer progressions. The parallel spectroscopic behaviors of the perturbed anharmonic ν22 and ν37 vibrations differ markedly from behavior observed for the quasiharmonic vibrations. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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