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Full-Text Articles in Physical Sciences and Mathematics
State-To-State Rate Coefficients For Hcs+In Rotationally Inelastic Collisions With H2at Low Temperatures, Otoniel Denis-Alpizar, Ernesto Quintas-Sánchez, Richard Dawes
State-To-State Rate Coefficients For Hcs+In Rotationally Inelastic Collisions With H2at Low Temperatures, Otoniel Denis-Alpizar, Ernesto Quintas-Sánchez, Richard Dawes
Chemistry Faculty Research & Creative Works
HCS+ ions have been detected in several regions of the interstellar medium (ISM), but an accurate determination of the chemical-physical conditions in the molecular clouds where this molecule is observed requires detailed knowledge of the collisional rate coefficients with the most common colliders in those environments. In this work, we study the dynamics of rotationally inelastic collisions of HCS+ + H2 at low temperature, and report, for the first time, a set of rate coefficients for this system. We used a recently developed potential energy surface for the HCS+-H2 van der Waals complex and …
Cf⁺ Excitation In The Interstellar Medium, Benjamin Desrousseaux, François Lique, Javier R. Goicoechea, Ernesto Quintas-Sánchez, Richard Dawes
Cf⁺ Excitation In The Interstellar Medium, Benjamin Desrousseaux, François Lique, Javier R. Goicoechea, Ernesto Quintas-Sánchez, Richard Dawes
Chemistry Faculty Research & Creative Works
The detection of CF+ in interstellar clouds potentially allows astronomers to infer the elemental fluorine abundance and the ionization fraction in ultraviolet-illuminated molecular gas. Because local thermodynamic equilibrium (LTE) conditions are hardly fulfilled in the interstellar medium (ISM), the accurate determination of the CF+ abundance requires one to model its non-LTE excitation via both radiative and collisional processes. Here, we report quantum calculations of rate coefficients for the rotational excitation of CF+ in collisions with para- and ortho-H2 (for temperatures up to 150 K). As an application, we present non-LTE excitation models that reveal population inversion …
Inelastic Rate Coefficients For Collisions Of C₆Hˉ With H₂ And He, Kyle M. Walker, François Lique, Fabien Dumouchel, Richard Dawes
Inelastic Rate Coefficients For Collisions Of C₆Hˉ With H₂ And He, Kyle M. Walker, François Lique, Fabien Dumouchel, Richard Dawes
Chemistry Faculty Research & Creative Works
The recent detection of anions in the interstellar medium has shown that they exist in a variety of astrophysical environments -- circumstellar envelopes, cold dense molecular clouds and star-forming regions. Both radiative and collisional processes contribute to molecular excitation and de-excitation in these regions so that the ‘local thermodynamic equilibrium’ approximation, where collisions cause the gas to behave thermally, is not generally valid. Therefore, along with radiative coefficients, collisional excitation rate coefficients are needed to accurately model the anionic emission from these environments. We focus on the calculation of state-to-state rate coefficients of the C6H- molecule in …