Radiolysis of H2O:CO2 ices by heavy energetic cosmic ray analogs
Radiolysis of H2O:CO2 ices by heavy energetic cosmic ray analogs
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重高能宇宙射线类似物对 H2O:CO2 冰的辐射分解
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
Ê. F. Silveira
中科院分区：
文献类型：
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作者：
S. Pilling;E. S. Duarte;A. Domaracka;H. Rothard;P. Boduch;Ê. F. Silveira
本文介绍了重、高电荷态和高能离子(52 MeV，58Ni13+)与纯H2O、纯CO2和混合H2O：CO2天体物理冰模拟物相互作用的实验研究。这项分析旨在模拟重宇宙射线在密集和寒冷的天体物理环境中引发的化学和物理化学相互作用，例如分子云或原恒星云。测量是在重离子加速器GANIL(法国卡昂的Grand Accelerateur National DIons Lourds)进行的。气体样品在13K下沉积在CSI衬底上，用傅里叶变换红外光谱仪在不同流量下进行原位分析。对所产生的物种的辐射裂解产率进行了量化。纯水冰和二氧化碳冰的离解截面分别为1.1x10cm2和1.9x10−13cm2。对于混合H2O：CO_2(10：1)，两种物质的离解截面均约为1×10−~(13)cm~2。实验测得纯CO_2冰的溅射产额为2.2×104molec ion−_1。当注量为2−~3×1012ion/cm~2时，CO_2/CO比基本恒定(∼为0.1)，与初始CO_2/H_2O比无关。H_2O_2/H_2O比率也有类似的行为，稳定在0.01，与初始H_2O柱密度或相对丰度无关。
An experimental study of the interaction of heavy, highly charged, and energetic ions (52 MeV 58Ni13+) with pure H2O, pure CO2 and mixed H2O:CO2 astrophysical ice analogs is presented. This analysis aims to simulate the chemical and the physicochemical interactions induced by heavy cosmic rays inside dense and cold astrophysical environments, such as molecular clouds or protostellar clouds. The measurements were performed at the heavy ion accelerator GANIL (Grand Accelerateur National d'Ions Lourds in Caen, France). The gas samples were deposited onto a CsI substrate at 13 K. In-situ analysis was performed by a Fourier transform infrared (FTIR) spectrometer at different fluences. Radiolysis yields of the produced species were quantified. The dissociation cross sections of pure H2O and CO2 ices are 1.1 and 1.9 ×10−13 cm2, respectively. For mixed H2O:CO2 (10:1), the dissociation cross sections of both species are about 1 × 10−13 cm2. The measured sputtering yield of pure CO2 ice is 2.2 × 104 molec ion−1. After a fluence of 2−3 × 1012 ions cm−2, the CO2/CO ratio becomes roughly constant (∼0.1), independent of the initial CO2/H2O ratio. A similar behavior is observed for the H2O2/H2O ratio, which stabilizes at 0.01, independent of the initial H2O column density or relative abundance.