Experimental investigation of the collision and optical properties of (sub)µm-sized ice and ice-coated dust particles

我们建议在宽温度范围和高真空条件下对（亚）μ m大小的水冰、冰涂层二氧化硅和纯二氧化硅颗粒与冰、二氧化硅和冰/尘埃目标进行低速撞击实验。这些实验的目的是模拟在致密和最冷的星际云中的粒子间碰撞，其中已经假设并观察到了通过凝聚的颗粒生长。最重要的是，我们感兴趣的是作为粒径的函数的水冰颗粒的粘附阈值，这是广泛使用的文献，但缺乏经验数据。最重要的是，我们还打算测量这些碰撞中的电荷转移，以评估摩擦带电是否是致密星际云中自由电荷载流子的可能来源，其中经典的电离源，即紫外线辐射和宇宙射线，是无效的。我们的研究将得到补充的松散颗粒合奏，我们将深入了解凝结的球形冰和冰涂层尘埃颗粒的光学特性的红外测量。凝聚，破碎，摩擦带电，和小颗粒团聚体的光学性质的组合过程的更深入的理解是需要校准模型的尘埃质量演变，化学演变，和辐射能量传输的分子云。

We propose to perform low-velocity impact experiments of (sub)μm-sized water ice, ice-coated silica, and pure silica particles with ice, silica, and ice/dust targets in a wide range of temperatures and under high-vacuum conditions. These experiments are intended to simulate inter-particle collisions in the densest and coldest interstellar clouds, for which grain growth by coagulation has been postulated and observed. Above all, we are interested in the sticking threshold for water-ice particles as a function of grain size, which is widely used in the literature but for which empirical data are lacking. On top of that, we also intend to measure the charge transfer in these collisions to assess whether triboelectric charging is a possible source for free charge carriers in dense interstellar clouds in which the classical sources of ionization, i.e. ultraviolet radiation and cosmic rays, are not effective. Our study will be complemented by infrared measurements of loose particle ensembles with which we will gain insight into the optical properties of coagulated spherical ice and ice-coated dust particles. A deeper understanding of the combined processes of coagulation, fragmentation, triboelectric charging, and optical properties of small particle agglomerates is required to calibrate models of the dust-mass evolution, the chemical evolution, and the radiative energy transport in molecular clouds.