论文标题
星际云中小PAH的弹性：通过快速辐射冷却的有效稳定氰基萘
Resilience of small PAHs in interstellar clouds: Efficient stabilization of cyanonaphthalene by fast radiative cooling
论文作者
论文摘要
经过数十年的猜测和搜索，天文学家最近在太空中鉴定了特定的多环芳烃（PAH）。值得注意的是，在金牛座分子云（TMC-1）中观察到的氰基萘（CNN，C10H7CN）的丰度比天体物理建模的预期高六个数量级。在这里，我们报告以其阳离子形式的1-CNN异构体的绝对单分子解离和辐射冷却速率系数。这些结果基于对时间依赖性中性产物发射速率和动能释放分布的测量结果，这些分布是从与星际云类似的环境中研究的内部激发1-CNN +集合产生的。我们发现，由于通过振动耦合的大量增强了电子过渡概率，因此通过热填充的电子激发态通过热填充的电子激发态进行了复发性荧光 - 辐射弛豫。我们的结果有助于解释CNN在TMC-1中的异常丰度，并挑战了空间中小PAH的快速破坏的广泛接受的情况。
After decades of speculation and searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud (TMC-1) is six orders of magnitude higher than expected from astrophysical modeling. Here, we report absolute unimolecular dissociation and radiative cooling rate coefficients of the 1-CNN isomer in its cationic form. These results are based on measurements of the time-dependent neutral product emission rate and Kinetic Energy Release distributions produced from an ensemble of internally excited 1-CNN + studied in an environment similar to that in interstellar clouds. We find that Recurrent Fluorescence - radiative relaxation via thermally populated electronic excited states - efficiently stabilizes 1-CNN+ , owing to a large enhancement of the electronic transition probability by vibronic coupling. Our results help explain the anomalous abundance of CNN in TMC-1 and challenge the widely accepted picture of rapid destruction of small PAHs in space.
