AI 中文总结
本研究利用HFML-FELIX实验室的红外自由电子激光，通过42次辐照实验探究多孔非晶固体水的重构与脱附规律，发现二者为独立过程，为相关天体物理研究提供了依据。
AI 中文摘要
水冰是星际介质（ISM）中最丰富的冰。此前对多孔非晶固体水（pASW）的研究表明，采用红外自由电子激光（FEL）辐照模拟的ISM红外辐射场可使冰发生变化，形成更有序的结构，特征是OH伸缩振动带发生改变。本文旨在通过改变辐照强度和辐照时间，更详细地研究这种重构，涉及与OH伸缩、弯曲和摇摆模式共振的辐照。此外，辐照过程中还监测H₂O的脱附。本研究针对以两种不同速率沉积的pASW样品进行了42次红外FEL辐照，使用HFML-FELIX实验室的红外FEL。在超高真空系统中，采用反射吸收红外（RAIR）光谱研究重构，并用质谱仪监测H₂O的脱附。脱附和重构同时发生，与OH伸缩振动共振的辐照效果最强。两种过程均呈现两个不同阶段：初始阶段是强烈的重构和脱附，特征为辐照最初5秒内脱附峰强度呈指数下降；随后进入第二阶段，重构效率降低但仍持续，脱附则在更大范围内保持恒定，涉及通过氢键网络的能量耗散。重构和脱附随辐照吸收能量的变化趋势存在显著差异，表明二者是独立过程。本文还讨论了第二阶段恒定脱附和重构的天体物理相关性。
英文摘要
Water ice is the most abundant ice in the interstellar medium (ISM). Previous studies on porous amorphous solid water (pASW) have shown that the infrared radiation field in the ISM modeled with infrared free electron laser (FEL) irradiation can result in changes in the ice towards a more ordered structure, characterized by a change in the OH-stretching vibration band. This paper aims to study the restructuring in more detail by varying the irradiation intensity and irradiation time for irradiations on-resonance with the OH-stretching, bending and libration modes. In addition, desorption of H2O is monitored during the irradiations. The research presented in this paper considers 42 infrared FEL irradiations on pASW samples deposited at two different rates, using the infrared FELs of the HFML-FELIX laboratory. Restructuring is studied using reflection absorption infrared (RAIR) spectroscopy, with a mass spectrometer monitoring the desorption of H2O in an ultra-high vacuum system. Desorption and restructuring occur in parallel, with the strongest effects observed for irradiation on-resonance with the OH-stretching vibration. Both processes exhibit two distinct regimes: an initial strong restructuring and desorption, characterized by an exponential decrease in the intensity of the desorption peaks within the first 5 s of irradiation, followed by a second regime of less efficient, yet continued restructuring and constant desorption in an extended area, involving energy dissipation through the hydrogen-bonding network. The trends in restructuring and desorption, depending on the absorbed energy during irradiation, are significantly different, suggesting separate processes. The astrophysical relevance of in particular the second regime of constant desorption and restructuring is discussed.
Comments14 pages, 7 figures in main text, 4 figures in Appendix
