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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Time-Resolved Study of 1,8-Naphthalic Anhydride and 1,4,5,8-Naphthalene-tetracarboxylic Dianhydride
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Time-Resolved Study of 1,8-Naphthalic Anhydride and 1,4,5,8-Naphthalene-tetracarboxylic Dianhydride

机译：1,8-萘酐和1,4,5,8-萘-四羧酸二酐的时间分辨研究

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摘要

We investigate the excited electronic states of 1,8-naphthalic anhydride (NDCA) and 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA) by time- and frequency-resolved electronic spectroscopy in the gas phase using picosecond lasers and by femtosecond time-resolved transient absorption in cyclohexane. The experiments are accompanied by calculations that yield the energy of the excited singlet and triplet states as well as by surface hopping dynamics simulations and calculations of spin-orbit couplings that give insight into the photochemistry. The origin of the A (1)A(1) <- X (1)A(1) (pi pi*) transition in isolated NDCA was found at 30 260 cm(-1) and several low-lying vibrational bands were observed. The lifetime drops sharply from 1.2 ns at the origin to around 30 ps at an excess energy of 800 cm(-1). Both internal conversion (IC) and intersystem crossing (ISC) are possible deactivation pathways as found in coupled electron-nuclear dynamics simulations. In cyclohexane solution, two time constants were observed. Deactivation of the initially excited state by ISC seems to dominate as supported by computations. For NTCDA we observed a gas phase lifetime of 16 ps upon excitation at 351 nm.
机译：我们使用皮秒激光在气相中通过时间和频率分辨电子光谱研究了1,8-萘酐（NDCA）和1,4,5,8-萘四甲酸二酐（NTCDA）的激发电子态飞秒时间分辨的在环己烷中的瞬时吸收。实验伴随着产生激发的单重态和三重态的能量的计算，以及表面跳变动力学模拟和自旋轨道耦合的计算，从而深入了解了光化学。在孤立的NDCA中发现A（1）A（1）<-X（1）A（1）（pi pi *）过渡的起源是在30260 cm（-1）处，并观察到几个低洼的振动带。寿命从原点的1.2 ns急剧下降到800 cm（-1）的多余能量下的大约30 ps。正如在耦合的电子-核动力学模拟中发现的那样，内部转换（IC）和系统间交叉（ISC）都是可能的失活途径。在环己烷溶液中，观察到两个时间常数。如计算所支持的那样，ISC对初始激发态的去激活似乎占主导地位。对于NTCDA，我们观察到在351 nm激发时的气相寿命为16 ps。

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