AI 中文总结
研究硅酸盐与碳质纳米颗粒碰撞，通过分子动力学模拟，确定碰撞速度控制相互作用，识别出四个速度区域及对应结果，给出破碎阈值速度，表明碰撞速度决定物理化学结果，为星际化学提供了相关机制。
AI 中文摘要
我们的总体目标是确定碰撞速度如何控制硅酸盐和碳质纳米颗粒之间的相互作用。具体目标包括：识别能够产生混合硅酸盐 - 碳质颗粒和/或化学复杂分子物种的碰撞机制；量化与尘埃破坏相关的破碎阈值速度。我们使用机器学习力场进行分子动力学模拟，以模拟质量相当的硅酸盐和碳质纳米颗粒之间的正面碰撞，碰撞速度范围为1 - 11千米/秒。对于所有碰撞，跟踪颗粒间混合程度和分子碎片形成情况。确定了四个速度区域：速度小于1.5千米/秒时颗粒相互反弹；1.5 - 3.5千米/秒时颗粒开始粘连；3.5 - 7.5千米/秒时颗粒倾向聚集并形成颗粒间化学键，产生稳定混合颗粒；速度大于7.5千米/秒时破碎占主导，产生CO等多种产物，破碎阈值速度约为7.5千米/秒。结果表明碰撞速度控制着硅酸盐 - 碳质纳米颗粒相互作用的物理和化学结果，在破碎区域为产生混合颗粒和多种分子物种提供了可行途径，建立了颗粒处理物理与观测到的复杂星际化学之间的简单可信机制。
英文摘要
Our overall objective is to determine how collision velocity governs the interactions between silicate and carbonaceous nanograins. We aim to: i) identify collisional regimes capable of producing mixed silicate-carbonaceous grains and/or chemically complex molecular species, and ii) quantify fragmentation threshold velocities related to dust destruction. We performed molecular dynamics simulations employing a machine-learning force field to model head-on collisions between silicate and carbonaceous nanograins of comparable masses. Collision velocities span 1 - 11 km/sec. For all collisions, we tracked the extent of grain-grain mixing and the formation of molecular fragments. We identified four velocity regimes: 1) <1.5 km/sec, where grains bounce off one another, 2) 1.5-3.5 km/sec, where sticking between the grains starts to occur, 3) 3.5-7.5 km/sec, where grains tend to aggregate and form inter-grain chemical bonds, yielding stable mixed grains, and 4) >7.5 km/sec, where fragmentation dominates. The latter regime produces CO as the main product, along with hydrocarbons, complex organic molecules, molecular silicates, and mixed carbonaceous-silicate clusters. The fragmentation threshold velocity for these collisions is approximately 7.5 km/sec. We show that collision velocities govern both the physical and chemical outcomes of silicate-carbonaceous nanograin interactions. In the fragmentation regime, collisions provide a viable pathway for generating mixed grains and a wide range of molecular species, many of which have been observationally detected. Here, we provide a simple credible mechanism linking the physics of grain processing with observed complex interstellar chemistry.
CommentsAccepted in A&A
DOI：10.1051/0004-6361/202661452
