Fine-structure resolved rotational transitions and database for CN+H2 collisions

Q2 Physics and Astronomy

Molecular Astrophysics Pub Date : 2018-06-01 DOI:10.1016/j.molap.2018.03.001

Hannah Burton , Ryan Mysliwiec , Robert C. Forrey , B.H. Yang , P.C. Stancil , N. Balakrishnan

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引用次数: 6

Abstract

Cross sections and rate coefficients for CN+H₂ collisions are calculated using the coupled states (CS) approximation. The calculations are benchmarked against more accurate close-coupling (CC) calculations for transitions between low-lying rotational states. Comparisons are made between the two formulations for collision energies greater than 10 cm⁻¹. The CS approximation is used to construct a database which includes highly excited rotational states that are beyond the practical limitations of the CC method. The database includes fine-structure resolved rotational quenching transitions for $v = 0$ and j ≤ 40, where v and j are the vibrational and rotational quantum numbers of the initial state of the CN molecule. Rate coefficients are computed for both para-H₂ and ortho-H₂ colliders. The results are shown to be in good agreement with previous calculations, however, the rates are substantially different from mass-scaled CN+He rates that are often used in astrophysical models.

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CN+H2碰撞的精细结构解析旋转跃迁和数据库

用耦合态(CS)近似计算了CN+H2碰撞的截面和速率系数。这些计算是针对低洼旋转状态之间转换的更精确的紧密耦合(CC)计算进行基准测试的。对碰撞能量大于10 cm−1的两种公式进行了比较。CS近似用于构建一个数据库，其中包含超出CC方法实际限制的高激发转动状态。该数据库包括v=0和j ≤ 40的精细结构解析旋转猝灭跃迁，其中v和j是CN分子初始态的振动和旋转量子数。计算了准h2和准h2对撞机的速率系数。结果显示与先前的计算非常一致，然而，速率与天体物理模型中经常使用的大规模CN+He速率有很大不同。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Molecular Astrophysics ASTRONOMY & ASTROPHYSICS-

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期刊介绍： Molecular Astrophysics is a peer-reviewed journal containing full research articles, selected review articles, and thematic issues. Molecular Astrophysics is a new journal where researchers working in planetary and exoplanetary science, astrochemistry, astrobiology, spectroscopy, physical chemistry and chemical physics can meet and exchange their ideas. Understanding the origin and evolution of interstellar and circumstellar molecules is key to understanding the Universe around us and our place in it and has become a fundamental goal of modern astrophysics. Molecular Astrophysics aims to provide a platform for scientists studying the chemical processes that form and dissociate molecules, and control chemical abundances in the universe, particularly in Solar System objects including planets, moons, and comets, in the atmospheres of exoplanets, as well as in regions of star and planet formation in the interstellar medium of galaxies. Observational studies of the molecular universe are driven by a range of new space missions and large-scale scale observatories opening up. With the Spitzer Space Telescope, the Herschel Space Observatory, the Atacama Large Millimeter/submillimeter Array (ALMA), NASA''s Kepler mission, the Rosetta mission, and more major future facilities such as NASA''s James Webb Space Telescope and various missions to Mars, the journal taps into the expected new insights and the need to bring the various communities together on one platform. The journal aims to cover observational, laboratory as well as computational results in the galactic, extragalactic and intergalactic areas of our universe.