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Using time-resolved infrared-vacuum-ultraviolet double-resonance spectroscopy, experimental room temperature measurements of state-to-state rate coefficients for rotational energy transfer within the X $^1\Sigma^+(v=2)$ vibrational state of…

Quantum Physics · Physics 2026-03-10 Hamza Labiad , Alexandre Faure , Ian R. Sims

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

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

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

Rate coefficients for state-to-state rotational transitions in CO induced by both para- and ortho-H$_2$ collisions are presented. The results were obtained using the close-coupling method and the coupled-states approximation, with the…

Solar and Stellar Astrophysics · Physics 2015-05-18 Benhui Yang , P. C. Stancil , N. Balakrishnan , R. C. Forrey

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

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…

The H$_2$+H$_2$ system has long been considered as a benchmark system for ro-vibrational energy transfer in bimolecular collisions. However, most studies thus far have focused on collisions involving H$_2$ molecules in the ground…

Chemical Physics · Physics 2022-12-20 James F. E. Croft , Pablo G. Jambrina , F. Javier Aoiz , Hua Guo , N. Balakrishnan

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

The interpretation of water line emission from existing observations and future HIFI/Herschel data requires a detailed knowledge of collisional rate coefficients. Among all relevant collisional mechanisms, the rotational (de)excitation of…

Astrophysics · Physics 2009-11-13 A. Faure , N. Crimier , C. Ceccarelli , P. Valiron , L. Wiesenfeld , M. -L. Dubernet

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

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

Rate coefficients for rotational transitions in H_2 induced by H_2 impact are presented. Extensive quantum mechanical coupled-channel calculations based on a recently published (H_2)_2 potential energy surface were performed. The potential…

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

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

The modelling of emission spectra of molecules seen in interstellar clouds requires the knowledge of collisional rate coefficients. Among the commonly observed species, N$_2$H$^+$ is of particular interest since it was shown to be a good…

Astrophysics of Galaxies · Physics 2015-06-23 François Lique , Fabien Daniel , Laurent Pagani , Nicole Feautrier

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

We have used archival far-ultraviolet spectra from observations made by HST/STIS and FUSE to determine the column densities and rotational excitation temperatures for CO and H2, respectively, along the lines of sight to 23 Galactic O and B…

Astrophysics · Physics 2009-01-19 Eric B. Burgh , Kevin France , Stephan R. McCandliss

A five-dimensional coupled states (5D-CS) approximation is used to compute cross sections and rate coefficients for CO+H2 collisions. The 5D-CS calculations are benchmarked against accurate six-dimensional close-coupling (6D-CC)…

Instrumentation and Methods for Astrophysics · Physics 2017-01-20 Christina Castro , Kyle Doan , Michael Klemka , Robert C. Forrey , B. H. Yang , Phillip C. Stancil , N. Balakrishnan

We present a rigorous study of vibrational relaxation in p-H2 + p-H2 collisions at cold and ultracold temperatures and identify an efficient mechanism of ro-vibrational energy transfer. If the colliding molecules are in different rotational…

Quantum Physics · Physics 2008-04-02 Goulven Quéméner , Naduvalath Balakrishnan , Roman V. Krems
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