Energetic photon irradiation of carbonaceous icy grains–laboratory studies on the interstellar ice-dust interface in star-forming regions

在致密的星际介质中，宇宙尘埃颗粒被分子冰层覆盖。这些由耐火材料和挥发性组分组成的颗粒预计将被高能光子连续照射。尘埃颗粒上约10纳米的薄分子冰层可以被光子穿透。它们可以与耐火粉尘材料相互作用，从而在冰/粉尘材料中和在冰-粉尘界面处激活光子诱导的反应。耶拿的天体物理实验室和星团物理小组与台湾的光处理光谱实验室之间拟议的项目致力于研究星际介质和恒星形成区域中冰尘颗粒的光子诱导改性。冰和灰尘之间的界面的特征在于由于颗粒的小尺寸和灰尘团块的高孔隙度而具有大的接触面积。DFG-MOST计划下的联合研究项目旨在研究高能光子引发的冰尘界面过程，包括真空紫外光子（E <10.9 eV），极紫外光子（E=11-40 eV）和软X射线光子（E= 80-1200 eV）。这项研究将解决三个不同的目标，即自由基与碳质粉尘表面可能的相互作用，导致材料的侵蚀，在冰尘界面的有机和益生元分子的形成和高能光子对耐火粉尘材料的组成和结构的影响。我们将包括无定形和氢化的无定形碳纳米粒子与富勒烯样结构的亚单位和硅酸盐/碳的混合物。系统的实验研究作为典型的星际参数，如温度和光子能量的功能将进行覆盖的纯冰，包括H2O，NH3，CH 4，H2S，N2和O2尘埃类似物。这个关于高能颗粒/冰处理的项目的成果将提高我们对星际颗粒演化的认识，并将有助于更好地了解行星系统和行星的成分。它对天体化学、天体生物学和（外）行星科学也很重要。该研究项目是对即将于2021年发射的詹姆斯韦伯太空望远镜的创新和及时准备，该望远镜将以极高的红外光谱分辨率和灵敏度揭示星际冰和尘埃的细节。

In the dense interstellar medium, cosmic dust grains are covered by a molecular ice layer. These grains consisting of a refractory and a volatile component are expected to be continuously irradiated by energetic photons. Thin molecular ice layers of about 10 nm on dust grains can be penetrated by photons. They can interact with the refractory dust material activating photon-induced reactions in the ice/dust material and at the ice-dust interface. The proposed project between the Laboratory Astrophysics and Cluster Physics Group in Jena and the Photoprocessing Spectroscopy Laboratory in Taiwan is dedicated to the investigation of photon-induced modifications of ice-dust grains in the interstellar medium and in star-forming regions. The interface between ice and dust is characterized by a large contact area due to the small sizes of particles and the high porosity of the dust agglomerates. The joint research project under the DFG-MOST program is established to study the ice-dust interface processing triggered by energetic photons comprising vacuum ultraviolet photons (E <10.9 eV), extreme ultraviolet photons (E=11-40 eV), and soft X-ray photons (E= 80-1200 eV). This research will address three different objectives namely the possible interactions of radicals with carbonaceous dust surfaces leading to the erosion of the material, the formation of organic and prebiotic molecules at the ice-dust interface and the effect of energetic photons on the composition and structure of the refractory dust materials. We will include amorphous and hydrogenated amorphous carbon nanoparticles with fullerene-like structural subunits and silicate/carbon mixtures. Systematic experimental studies as a function of typical interstellar parameters such as temperature and photon energy will be performed on dust analogs covered by pure ices including H2O, NH3, CH4, H2S, N2 and O2. The outcome of this project on energetic grain/ice processing will improve our knowledge on the interstellar grain evolution and will help to better understand the ingredients of planetary systems and planets. It will also be important for Astrochemistry, Astrobiology, and (Exo-)Planetary Science. The research project is an innovative and timely preparation of the upcoming James Webb Space Telescope expected to be launched in 2021, which will reveal the details of interstellar ice and dust in exceptionally high IR spectral resolution and sensitivity.