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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

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 calculated rate coefficients for ro-vibrational transitions of CO in collisions with H atoms for a gas temperature range of 10 K $\leq T \leq$ 3000 K, based on the recent three-dimensional ab initio H-CO interaction potential of…

Astrophysics of Galaxies · Physics 2015-11-23 L. Song , N. Balakrishnan , K. M. Walker , P. C. Stancil , W. F. Thi , I. Kamp , A. van der Avoird , G. C. Groenenboom

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

Carbon monoxide is a simple molecule present in many astrophysical environments, and collisional excitation rate coefficients due to the dominant collision partners are necessary to accurately predict spectral line intensities and extract…

Astrophysics of Galaxies · Physics 2015-11-17 Kyle M. Walker , L. Song , B. H. Yang , G. C. Groenenboom , A. van der Avoird , N. Balakrishnan , R. C. Forrey , P. C. Stancil

Full-dimensional quantum scattering calculations are reported for ro-vibrational transitions in HD+HD collisions using a highly accurate interaction potential for the H$_2$-H$_2$ system. Several near-resonant ro-vibrational transitions are…

Atomic Physics · Physics 2026-03-06 Bikramaditya Mandal , Hubert Jóźwiak , Piotr Wcisło , Naduvalath Balakrishnan

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 -…

A close coupling quantum-mechanical calculation is performed for rotational energy transfer in a HD+HD collision at very low energy, down to the ultracold temperatures: $T \sim 10^{-8}$ K. A global six-dimensional H$_2$-H$_2$ potential…

Chemical Physics · Physics 2015-06-03 Renat A. Sultanov , Dennis Guster , S. K. Adhikari

New quantum scattering calculations for rotational deexcitation transitions of CO induced by H collisions using two CO-H potential energy surfaces (PESs) from Shepler et al. (2007) are reported. State-to-state rate coefficients are computed…

Solar and Stellar Astrophysics · Physics 2015-06-15 Benhui Yang , P. C. Stancil , N. Balakrishnan , R. C. Forrey , J. M. Bowman

The availability of collisional rate coefficients with H$_2$ is a pre-requisite for interpretation of observations of molecules whose energy levels are populated under non local thermodynamical equilibrium conditions. In the current study,…

Astrophysics of Galaxies · Physics 2015-06-22 F. Daniel , A. Faure , L. Wiesenfeld , E. Roueff , D. C. Lis , P. Hily-Blant

Cross sections for the rotational (de)excitation of CO by ground state para- and ortho-H_2 are obtained using quantum scattering calculations for collision energies between 1 and 520 cm^{-1}. A new CO-H_2 potential energy surface is…

Astrophysics · Physics 2008-11-26 M. Wernli , P. Valiron , A. Faure , L. Wiesenfeld , P. Jankowski , K. Szalewicz

Rotational transitions in molecular hydrogen collisions are computed. The two most recently developed potential energy surfaces for the H2-H2 system are used from the following works: 1) A.I. Boothroyd, P.G. Martin, W.J. Keogh, M.J.…

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

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

Collisions between hot hydrogen atoms and CO$_2$ play a central role in energy transfer and atmospheric escape in CO$_2$-rich planetary atmospheres. We present quantum mechanical $j_z$-conserving coupled-states calculations of…

Earth and Planetary Astrophysics · Physics 2025-12-25 Cheikh T. Bop , Marko Gacesa

Aim: We present an improved database of temperature dependent rate coefficients for rotational state-to-state transitions in H$_{2}$O + H$_{2}$O collisions. The database includes 231 transitions between the lower $para$- and 210 transitions…

Chemical Physics · Physics 2023-10-19 Bikramaditya Mandal , Dmitri Babikov

Astrophysical modeling of processes in environments that are not in local thermal equilibrium requires the knowledge of state-to-state rate coefficients of rovibrational transitions in molecular collisions. These rate coefficients can be…

Chemical Physics · Physics 2022-07-13 Taha Selim , Ad van der Avoird , Gerrit C. Groenenboom

The rovibrational level populations, and subsequent emission in various astrophysical environments, is driven by inelastic collision processes. The available rovibrational rate coefficients for water have been calculated using a number of…

Astrophysics of Galaxies · Physics 2024-11-14 Benhui Yang , Chen Qu , J. M. Bowman , Dongzheng Yang , Hua Guo , N. Balakrishnan , R. C. Forrey , P. C. Stancil

Accurate rate coefficients for molecular vibrational transitions due to collisions with H$_2$, critical for interpreting infrared astronomical observations, are lacking for most molecules. Quantum calculations are the primary source of such…

Solar and Stellar Astrophysics · Physics 2015-06-23 Benhui Yang , P. Zhang , X. Wang , P. C. Stancil , J. M. Bowman , N. Balakrishnan , R. C. Forrey

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

A scattering resonance is one of the most striking quantum effects in low-temperature molecular collisions. Predicted decades ago theoretically, they have only been resolved experimentally for systems involving at most four atoms. Extension…

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