Rotational relaxation of HCO+ and DCO+ by collision with H2
Rotational relaxation of HCO+ and DCO+ by collision with H2
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HCO 和 DCO 与 H2 碰撞发生旋转弛豫
DOI：
10.1093/mnras/staa2308
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发表时间：
2020
影响因子：
4.8
通讯作者：
S. Guilloteau
中科院分区：
文献类型：
--
作者：
O. Denis;T. Stoecklin;A. Dutrey;S. Guilloteau
HCO+ 和 DCO+ 分子通常用作星际介质中的示踪剂。因此，这些具有 He 和 H2 的系统的精确旋转速率系数在非局部热平衡模型中至关重要。在这项工作中，我们确定了 HCO+ 与对氢和邻氢碰撞时的旋转退激发率系数，并通过研究 DCO+ 的情况来分析同位素效应。为 HCO+–H2 系统开发了一种新的从头计算的四维势能面，并适用于 DCO+–H2 情况。然后将这些表面用于紧耦合计算，以确定 HCO+ 和 DCO+ 较低旋转状态的旋转去励磁截面和速率系数。将 HCO++ 对 H2 的新速率系数与现有数据进行了比较，并且还报告了 HCO++ 邻 H2 的一组速率系数。发现邻位氢和对位氢的碰撞率之间的差异很小。这些计算证实，使用 HCO++ 对 H2 的速率系数来估计 HCO++ 邻 H2 以及 DCO++ 对 H2 的速率系数是一个很好的近似值。
The HCO+ and DCO+ molecules are commonly used as tracers in the interstellar medium. Therefore, accurate rotational rate coefficients of these systems with He and H2 are crucial in non-local thermal equilibrium models. We determine in this work the rotational de-excitation rate coefficients of HCO+ in collision with both para- and ortho-H2, and also analyse the isotopic effects by studying the case of DCO+. A new four-dimensional potential energy surface from ab initio calculations was developed for the HCO+–H2 system, and adapted to the DCO+–H2 case. These surfaces are then employed in close-coupling calculations to determine the rotational de-excitation cross-sections and rate coefficients for the lower rotational states of HCO+ and DCO+. The new rate coefficients for HCO+ + para-H2 were compared with the available data, and a set of rate coefficients for HCO+ + ortho-H2 is also reported. The difference between the collision rates with ortho- and para-H2 is found to be small. These calculations confirm that the use of the rate coefficients for HCO+ + para-H2 for estimating those for HCO+ + ortho-H2 as well as for DCO+ + para-H2 is a good approximation.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell