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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ultrafast Studies on the Photophysics of Matrix-Isolated Radical Cations of Polycyclic Aromatic Hydrocarbons
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Ultrafast Studies on the Photophysics of Matrix-Isolated Radical Cations of Polycyclic Aromatic Hydrocarbons

机译：超快的多环芳烃基体自由基自由基的光物理研究

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Ultrafast relaxation dynamics for photoexcited PAH cations isolated in boric acid glass have been studied using femtosecond and picosecond transient grating spectroscopy. With the exception of perylene~+, the recovery kinetics for the ground doublet (D_0) states of these radical cations are biexponential, containing fast (<200 fs) and slow (3-20 ps) components. No temperature dependence or isotope effect was observed for the fast component, whereas the slow component exhibits both the H/D isotope effect (1.1-1.3) and a strong temperature dependence (15 to 300 K). We suggest that the fast component is due to internal D_n to D_0 conversion and that the slow component is due to vibrational energy transfer (VET) from a hot D_0 state to the glass matrix. The observed rapid, efficient deactivation of the photoexcited PAH cations accounts for their remarkable photostability and has important implications for astrochemistry because these cations are the leading candidates for the species responsible for the diffuse interstellar bands (DIB) observed throughout the galaxy.
机译：使用飞秒和皮秒瞬态光栅光谱技术研究了硼酸玻璃中分离的光激发PAH阳离子的超快弛豫动力学。除per离子外，这些自由基阳离子的基态双重态（D_0）的恢复动力学是双指数的，包含快速（<200 fs）和慢速（3-20 ps）的组分。快的组分没有观察到温度依赖性或同位素效应，而慢的组分同时表现出H / D同位素效应（1.1-1.3）和强的温度依赖性（15-300 K）。我们建议快速分量归因于内部D_n到D_0的转换，而缓慢分量归因于从热D_0状态到玻璃基体的振动能量转移（VET）。观察到的光激发的PAH阳离子快速，有效的失活是其显着的光稳定性的原因，并且对天化学具有重要意义，因为这些阳离子是负责整个银河系中弥散星际带（DIB）的物种的主要候选物。

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