H + HeH+→ H2+ + He反应的低温动态:关于远程相互作用的重要性
Jayakrushna Sahoo1, Duncan Bossion2, Tomás González-Lezana3
1Laboratoire Univers et Particules de Montpellier, Université de Montpellier, UMR-CNRS 5299, 34095 Montpellier Cedex, France.
The Journal of chemical physics
|October 14, 2024
概括
对像H+HeH+这样的离子中性反应的准确建模至关重要. 纳入远程相互作用可以解决人造障碍,提高速率系数,并改善早期宇宙化学的预测.
科学领域:
- 化学物理 化学物理
- 天体化学是天体化学.
- 量子化学 是一个量子化学.
背景情况:
- 在冷碰撞中,越来越多地认识到远程相互作用,但在关键的离子中性反应中却被忽视了.
- 之前对H + HeH + 反应的研究表明,由于潜在能量表面 (PES) 的限制,在低能量的情况下表现出非朗格温行为.
研究的目的:
- 为了研究远程相互作用对H+HeH+反应的影响.
- 开发一个精细的潜在能量表面 (PES),准确地描述HeH2+系统.
- 重新评估低能反应速率系数及其对天体化学的影响.
主要方法:
- 将精确的远程相互作用项纳入潜在能量表面 (PES).
- 为HeH2+系统进行高层次的初始电子结构计算.
- 应用经典,量子和统计方法来计算反应动态和速率系数.
主要成果:
- 为HeH2+系统开发了一种新的,精细的,无障碍的PES,准确地反映了初始能量.
- 修正后的 PES 解决了人造障碍,导致低温速率系数显著提高.
- 计算的速率系数现在与兰格温的行为保持一致,与以前的结果有很大不同.
结论:
- 精确的远程术语对于准确建模反应性PES,特别是离子中性反应至关重要.
- 对H+HeH+反应的增强速率系数影响了早期宇宙条件下HeH+丰度的预测.
- 这项工作强调了精确的 PES 在天体化学和反应动态学的重要性.
相关概念视频
Hess's Law
44.6K
There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally determined enthalpy changes. Some reactions are difficult, if not impossible, to investigate and make accurate measurements for experimentally. And even when a reaction is not hard to perform or measure, it is convenient to be able to determine the heat involved in a reaction without having to perform an experiment.
44.6K
Thermochemical Equations
28.3K
For a chemical reaction (the system) carried out at constant pressure – with the only work done caused by expansion or contraction – the enthalpy of reaction (also called the heat of reaction, ΔHrxn) is equal to the heat exchanged with the surroundings (qp).
28.3K
Le Chatelier's Principle: Changing Temperature
29.4K
Consistent with the law of mass action, an equilibrium stressed by a change in concentration will shift to re-establish equilibrium without any change in the value of the equilibrium constant, K. When an equilibrium shifts in response to a temperature change, however, it is re-established with a different relative composition that exhibits a different value for the equilibrium constant.
To understand this phenomenon, consider the elementary reaction:
To understand this phenomenon, consider the elementary reaction:
29.4K
Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
2.6K
The addition of a hydrogen halide to 1,3-butadiene gives a mixture of 1,2- and 1,4-adducts. Since more substituted alkenes are more stable, the 1,4-adduct is expected to be the major product. However, the product distribution is strongly influenced by temperature; low temperature favors the 1,2-adduct, whereas the 1,4-adduct is predominant at high temperature.
2.6K
Radical Anti-Markovnikov Addition to Alkenes: Thermodynamics
1.8K
The anti-Markovnikov addition of hydrogen halides to an alkene is thermodynamically feasible only with HBr. The radical addition reaction with other hydrogen halides like HCl and HI is thermodynamically unfavorable.
1.8K
Acid-Catalyzed Hydration of Alkenes
13.7K
Alkenes react with water in the presence of an acid to form an alcohol. In the absence of acid, hydration of alkenes does not occur at a significant rate, and the acid is not consumed in the reaction. Therefore, alkene hydration is an acid-catalyzed reaction.
13.7K


