Acceleration of intramolecular vibrational redistribution by methyl internal rotation. II. A comparison of m‐fluorotoluene and p‐fluorotoluene
Acceleration of intramolecular vibrational redistribution by methyl internal rotation. II. A comparison of m‐fluorotoluene and p‐fluorotoluene
复制标题
甲基内旋转加速分子内振动重新分布 II。
DOI：
10.1063/1.466685
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发表时间：
1994
影响因子：
4.4
通讯作者：
D. Moss
中科院分区：
文献类型：
--
作者：
P. Timbers;C. Parmenter;D. Moss
在有和没有甲基内旋转的芳香族分子的S1流形内的分子内振动再分布（IVR）的速率常数的比较已经扩展到Meta氟甲苯（mFT）。通过O2荧光猝灭（化学计时）方法测定的IVR速率常数为8.2×1011 s−1，零级能级31，evib = 1250 cm−1。该速率约为帕拉氟甲苯（pFT）中可比水平的10倍。pFT中的IVR率又超过帕拉二氟苯（pDFB）中相当水平的IVR率40倍。我们认为这些差异使用费米黄金法则制定IVR速率常数。mFT与pFT的增强值可能是内旋转和分子振动之间的耦合强度增加加上增加耦合态密度的因素的组合的结果。这一结果与pFT和pDFB之间的比较相反，其中IVR加速主要归因于...
Comparisons of rate constants for intramolecular vibrational redistribution (IVR) within the S1 manifolds of aromatic molecules with and without methyl internal rotation have been extended to meta‐fluorotoluene (mFT). The IVR rate constant, as determined by the method of O2 fluorescence quenching (chemical timing), is 8.2×1011 s−1 for the zero‐order level 31 with evib≊1250 cm−1. This rate is approximately 10 times greater than that for the comparable level in para‐fluorotoluene (pFT). The IVR rate in pFT in turn exceeds that for a comparable level in para‐difluorobenzene (pDFB) by a factor of 40. We consider these differences using the Fermi golden rule formulation of the IVR rate constant. The enhanced value for mFT vs pFT may be a consequence of increased coupling strength between the internal rotation and molecular vibration plus a combination of factors that increase the coupled state density. This result is in contrast to the comparison between pFT and pDFB, where IVR acceleration is attributed prima...