Wenthold PG, Hrovat DA, Borden WT, Lineberger WC
P. G. Wenthold and W. C. Lineberger, JILA and Department of Chemistry and Biochemistry, University of Colorado, and National Institute of Standards and Technology, Boulder, CO 80309, USA. D. A. Hrovat and W. T. Borden, Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195, USA.
Science. 1996 Jun 7;272(5267):1456-9. doi: 10.1126/science.272.5267.1456.
The 351-nanometer photoelectron spectrum of the planar cyclooctatetraene radical anion (COT·-) shows transitions to two electronic states of cyclooctatetraene (COT). These states correspond to the D4h 1A1g state, which is the transition state for COT ring inversion, and the D8h 3A2u state. The electron binding energy of the 1A1g transition state is 1.099 ± 0.010 electron volts, which is lower by 12.1 ± 0.3 kilocalories per mole than that of the 3A2u state. The photoelectron spectrum shows that the singlet lies well below the triplet in D8h COT and confirms ab initio predictions that the molecule violates Hund's rule. Vibrational structure is observed for both features and is readily assigned by use of a simple potential energy surface.
平面环辛四烯自由基阴离子（COT⁻·）的351纳米光电子能谱显示出向环辛四烯（COT）的两个电子态的跃迁。这些态对应于D4h 1A1g态，它是COT环反转的过渡态，以及D8h 3A2u态。1A1g过渡态的电子结合能为1.099 ± 0.010电子伏特，比3A2u态的电子结合能低12.1 ± 0.3千卡每摩尔。光电子能谱表明，在D8h COT中，单重态远低于三重态，并证实了从头算预测该分子违反洪德规则。两种特征均观察到了振动结构，并且通过使用简单的势能面很容易进行归属。
