在非平衡时代的非弹性碰撞动力学中,单体尺寸效应在非弹性碰撞动力学中
Alexander N Morozov1, Alexander M Mebel1, Michael Frenklach2
1Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
The Journal of chemical physics
|December 16, 2024
概括
较大的多环芳 (PAHs) 通过非平衡过程更有效地变质. 分子动力学模拟表明,这种尺寸效应增强了交联反应,与较小的烯系统相比,冠烯系统的二元化率显著增加.
科学领域:
- 物理化学 物理化学
- 计算化学的计算化学
- 天体化学是天体化学.
背景情况:
- 多环芳香碳化合物 (PAHs) 在星际空间中非常丰富.
- 了解PAH二分化对于天体化学和材料科学至关重要.
- 之前的研究探讨了以烯为基础的系统,但较大的PAH的影响仍然不太清楚.
研究的目的:
- 为了研究多环芳 (PAHs) 对非平衡二分化的大小影响.
- 为了比较冠 - 烯和冠基 - 烯对与较小的烯系统的碰撞动态.
- 阐明非弹性碰撞和能量消散在PAH二元化中的作用.
主要方法:
- 用分子动力学 (MD) 模拟来建模PAH对的碰撞动力学.
- 模拟的重点是冠烯-阿西和冠烯基-阿西系统.
- 反应事件直接计数以估计速率常数并与理论计算进行比较.
主要成果:
- 非平衡的范德瓦尔斯二分化随着PAH大小的增加而增强.
- 较大的PAHs,如冠烯,显示放大不弹性碰撞动力学,导致共价键的形成.
- 据估计,冠基-阿西皮林协会的前期速率常数为~10^-11 cm^3分子^-1 s^-1,比统计计算增加了15倍.
- 统计 (基于平衡) 的计算越来越低估了较大的PAH的反应速率.
结论:
- 碰撞的PAH单体的大小显著影响非平衡二分化.
- 增加PAH大小可以提高二分化效率,因为更大的低频模式池作为能量沉积器.
- 与平衡模型相比,MD模拟可以更准确地评估较大的PAHs的反应速率.
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