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Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations…

Solar and Stellar Astrophysics · Physics 2015-06-10 Benhui Yang , K. M. Walker , R. C. Forrey , P. C. Stancil , N. Balakrishnan

We report the first full-dimensional potential energy surface (PES) and quantum mechanical close-coupling calculations for scattering of SiO due to H$_2$. The full-dimensional interaction potential surface was computed using the explicitly…

A new database of collisional rate coefficients for transitions between the rotational states of H$_2$O collided with H$_2$ background gas is developed. The goal is to expand over the other existing databases in terms of the rotational…

Quantum Physics · Physics 2024-12-18 Carolin Joy , Dulat Bostan , Bikramaditya Mandal , Dmitri Babikov

OH is a cornerstone molecule in the chemistry of interstellar and circumstellar media and is ubiquitously detected in warm gas thanks to its infrared rotational lines. However, the excitation processes of OH remain poorly characterized. We…

Modeling environments that are not in local thermal equilibrium, such as protoplanetary disks or planetary atmospheres, with molecular spectroscopic data from space telescopes requires knowledge of the rate coefficients of rovibrationally…

Atomic Physics · Physics 2023-10-10 Taha Selim , Ad van der Avoird , Gerrit C. Groenenboom

Rates for rotational excitation of HC3N by collisions with He atoms and H2 molecules are computed for kinetic temperatures in the range 5-20K and 5-100K, respectively. These rates are obtained from extensive quantum and quasi-classical…

Chemical Physics · Physics 2009-11-13 Michael Wernli , Laurent Wiesenfeld , Alexandre Faure , Pierre Valiron

We report quantum-mechanical close-coupling calculations for rotational state resolved cross sections for p-H2+HD collisions. The low temperature limit of p-H2+HD is investigated, which is of significant astrophysical interest in regard to…

Chemical Physics · Physics 2015-06-26 Renat A. Sultanov , Dennis Guster

We present quantum mechanical close-coupling calculations of collisions between two hydrogen molecules over a wide range of energies, extending from the ultracold limit to the super-thermal region. The two most recently published potential…

Atomic Physics · Physics 2009-11-13 Teck-Ghee Lee , N. Balakrishnan , R. C. Forrey , P. C. Stancil , D. R. Schultz , Gary J. Ferland

State-selected total cross sections and thermal rate coefficients are computed for the HD + $ortho$-/$para$-H$_2$ rotational energy transfer collision at low temperatures: 2 K $\lesssim$ T $\lesssim$ 300 K. A modified H$_2$-H$_2$ potential…

Chemical Physics · Physics 2016-01-28 Renat A. Sultanov , Dennis Guster , S. K. Adhikari

Quantum-mechanical close-coupling calculations for state-to-state cross sections and thermal rates are reported for H2+H2 collisions. Two recently developed potential energy surfaces (PES) for the H2-H2 system are applied, namely, the…

Chemical Physics · Physics 2009-11-11 Renat A. Sultanov , Dennis Guster

The hydronium cation plays a crucial role in interstellar oxygen and water chemistry. While its spectroscopy was extensively investigated earlier, the collisional excitation of H$_3$O$^+$ is not well studied yet. In this work we present…

Chemical Physics · Physics 2022-11-07 S. Demes , François Lique , Alexandre Faure , Floris van der Tak , Claire Rist , Pierre Hily-Blant

The low-temperature (up to about 100K) collisional (de)excitation cross sections are computed using the full coupled-channel (CC) quantum dynamics for both Li$_2$ and Li$_2^+$ molecular targets in collision with $^4$He. The interaction…

Chemical Physics · Physics 2007-07-13 M. Wernli. E. Bodo , F. A. Gianturco

Using a quantum-mechanical close-coupling method, we calculate cross sections for fine structure excitation and relaxation of Si and S atoms in collisions with atomic hydrogen. Rate coefficients are calculated over a range of temperatures…

Atomic Physics · Physics 2024-12-10 Pei-Gen Yan , James F. Babb

Experimental measurements and theoretical calculations of state-to-state rate coefficients for rotational energy transfer of CO in collision with H$_2$ are reported at the very low temperatures prevailing in dense interstellar clouds (5 -…

State-to-state differential cross sections (DCSs) for rotationally inelastic scattering of H2O by H2 have been measured at 71.2 meV (574 cm-1) and 44.8 meV (361 cm-1) collision energy using crossed molecular beams combined with velocity map…

Chemical Physics · Physics 2015-05-27 C-H. Yang , G. Sarma , D. H. Parker , J. J ter Meulen , L. Wiesenfeld

We present quantum mechanical and quasiclassical trajectory calculations of cross sections for rovibrational transitions in ortho- and para-H_2 induced by collisions with He atoms. Cross sections were obtained for kinetic energies between…

Astrophysics · Physics 2007-05-23 N. Balakrishnan , M. Vieira , J. F. Babb , R. C. Forrey , A. Dalgarno , S. Lepp

We use state- and time-resolved coherent Raman spectroscopy to study the rotational dynamics of oxygen molecules in ultra-high rotational states. While it is possible to reach rotational quantum numbers up to $N \approx 50$ by increasing…

Chemical Physics · Physics 2015-06-19 Alexander A. Milner , Aleksey Korobenko , Valery Milner

Motivated by recent observations with Herschel/PACS, and the availability of new rate coefficients for the collisional excitation of CO (Yang et al. 2010), the excitation of warm astrophysical CO is revisited with the use of numerical and…

Astrophysics of Galaxies · Physics 2015-06-04 David A. Neufeld

Nitric oxide is an open-shell molecule abundantly detected in the interstellar medium. A precise modeling of its radiative and collisional processes opens the path to a precise estimate of its abundance. We present here the first rate…

Astrophysics of Galaxies · Physics 2022-05-11 M. Ben Khalifa , J. Loreau

Modeling of molecular emission from interstellar clouds requires the calculation of rates for excitation by collisions with the most abundant species. The present paper focuses on the calculation of rate coefficients for rotational…

Astrophysics of Galaxies · Physics 2015-05-18 E. Sarrasin , D. Ben Abdallah , M. Wernli , A. Faure , J. Cernicharo , F. Lique