Electron-intramolecular-vibration interactions in positively charged phenanthrene-edge-type hydrocarbons
Electron-intramolecular-vibration interactions in positively charged phenanthrene-edge-type hydrocarbons
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DOI：
10.1063/1.1640351
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发表时间：
2004-02-15
影响因子：
4.4
通讯作者：
Yamabe, T
中科院分区：
文献类型：
--
作者：
Kato, T;Yamabe, T
本文研究了菲、芘和芘等菲边型碳氢化合物中的电子-声子相互作用。菲边型碳氢化合物中1500 cm ~（-1）附近的C-C伸缩模和500 cm ~（-1）附近的低频模与最高占据分子轨道（HOMO）强耦合。菲、蒽和芘的一价阳离子的总电子-声子耦合常数分别为0.251、0.135和0.149 eV，估计大于蒽、并四苯和并五苯的一价阳离子的总电子-声子耦合常数分别为0.130、0.107和0.094 eV。并苯边型烃中位于分子边缘的碳原子上的HOMO与菲边型烃中的离域HOMO的相位模式差异是导致这一结果的主要原因。HOMO中两个相邻碳原子之间的轨道相互作用的强度随着分子尺寸的增大而变弱，因为在菲边型烃中，HOMO中每个碳原子上的电子密度随着分子尺寸的增大而变小。另一方面，并苯边型碳氢化合物的前线轨道具有一定的非键特征，与菲边型碳氢化合物的前线轨道相比，不能与完全对称的振动模强耦合.这就是菲边型烃的I（HOMO）值随着分子尺寸的增加而比并苯边型烃更显著地减小的原因，以及具有C-2 v几何构型的聚菲的I（HOMO）值（0.033 eV）被估计为与聚并苯的I（HOMO）值（0.036 eV）相似的原因。大分子菲边型烃的中性分子与相应一价阳离子的重组能比大分子并苯边型烃的重组能大。(C)2004年，美国物理学会。
Electron-phonon interactions in positively charged phenanthrene-edge-type hydrocarbons such as phenanthrene, chrysene, and picene are studied. The C-C stretching modes around 1500 cm-1 and the low-frequency modes around 500 cm(-1) strongly couple to the highest occupied molecular orbitals (HOMO) in phenanthrene-edge-type hydrocarbons. The total electron-phonon coupling constants for the monocations (l(HOMO)) of 0.251, 0.135, and 0.149 eV for phenanthrene, chrysene, and picene, respectively, are estimated to be larger than those of 0.130, 0.107, and 0.094 eV for anthracene, tetracene, and pentacene, respectively. The phase patterns difference between the HOMO localized on carbon atoms which are located at the molecular edge in acene-edge-type hydrocarbons and the delocalized HOMO in phenanthrene-edge-type hydrocarbons is the main reason for the result. Strengths of orbital interactions between two neighboring carbon atoms in the HOMO become weaker with an increase in molecular size because the electron density on each carbon atom in the HOMO becomes smaller with an increase in molecular size in phenanthrene-edge-type hydrocarbons. On the other hand, the frontier orbitals of acene-edge-type hydrocarbons have somewhat nonbonding characters and thus cannot strongly couple to the totally symmetric vibrational modes compared with the frontier orbitals of phenanthrene-edge-type hydrocarbons. This is the reason why the l(HOMO) value for phenanthrene-edge-type hydrocarbons decreases with an increase in molecular size more significantly than that for acene-edge-type hydrocarbons, and the reason why the l(HOMO) value for polyphenanthrene with C-2v geometry (0.033 eV) is estimated to be similar to that for polyacene (0.036 eV). The reorganization energies between the neutral molecules and the corresponding monocations for phenanthrene-edge-type hydrocarbons with large molecular size are estimated to be larger than those for acene-edge-type hydrocarbons with large molecular size. (C) 2004 American Institute of Physics.