This joint theoretical and experimental study establishes that the adsorption of polycyclic aromatic hydrocarbons (PAHs) onto the amorphous ice surface provokes a broadening and redshift of the “dangling” OH (dOH) ice spectral feature, the redshift increasing with PAH size up to ∼85 cm^–1. It also reveals that, in certain interaction configurations, adsorption induces substantial reorganization of the hydrogen-bonding network at the ice surface. Comparison with experiments validates the novel theoretical methodology relying on the density functional-based tight binding approach, which offers a compromise between the system size and accuracy, enabling a wide sampling of surface structures. Applied in an astrophysical context, this study suggests that widening of the dOH feature by adsorption of aromatic molecules could explain its absence heretofore in observational ice spectra, offering hope that future missions with higher sensitivity will verify its presence or absence in dense regions.

中文翻译：

---

多环芳烃的吸附对非晶态固体水表面的扰动

这项联合的理论和实验研究表明，多环芳烃（PAHs）在无定形冰面上的吸附引发了“悬空的” OH（dOH）冰光谱特征的扩大和红移，红移随PAH的大小增加而增大，直至〜85厘米^–1。它也揭示出，在某些相互作用的配置中，吸附会引起冰表面氢键网络的实质性重组。与实验的比较验证了依赖于基于密度泛函的紧密结合方法的新颖理论方法，该方法在系统尺寸和精度之间进行折衷，从而可以对表面结构进行广泛的采样。在天文物理环境中应用的这项研究表明，通过芳香族分子的吸附来扩大dOH特征可以解释迄今为止在观测冰光谱中不存在的dOH特征，这提供了希望，未来以更高灵敏度进行的任务将验证其在稠密区域中的存在与否。