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Inelastic collisions and elementary chemical reactions proceeding through the formation and subsequent decay of an intermediate collision complex, with an associated deep well on the potential energy surface, pose a challenge for accurate…

Chemical Physics · Physics 2022-06-10 Maarten Konings , Benjamin Desrousseaux , François Lique , Jérôme Loreau

Data for inelastic processes due to hydrogen atom collisions with iron are needed for accurate modelling of the iron spectrum in late-type stars. Excitation and charge transfer in low-energy Fe+H collisions is studied theoretically using a…

Solar and Stellar Astrophysics · Physics 2018-05-09 P. S. Barklem

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

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

Ammonia is one of the most widely observed molecules in space, and many observations are able to resolve the hyperfine structure due to the electric quadrupole moment of the nitrogen nucleus. The observed spectra often display anomalies in…

Astrophysics of Galaxies · Physics 2023-09-06 J. Loreau , A. Faure , F. Lique , S. Demes , P. J. Dagdigian

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 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

Our current understanding of interstellar carbon fractionation hinges on the interpretation of astrochemical kinetic models. Yet, the various reactions included carry large uncertainties in their (estimated) rate coefficients, notably those…

Astrophysics of Galaxies · Physics 2021-03-24 C. M. R. Rocha , H. Linnartz

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

In order to improve our understanding of the kinetics of the cometary coma, theoretical studies of the major reactive collisions in these environments are needed. Deep in the collisional coma, inelastic collisions between thermal electrons…

Earth and Planetary Astrophysics · Physics 2018-07-18 Y. Moulane , J. Zs. Mezei , V. Laporta , E. Jehin , Z. Benkhaldoun , I. F. Schneider

Data for inelastic processes due to hydrogen atom collisions with manganese and titanium are needed for accurate modeling of the corresponding spectra in late-type stars. In this work excitation and charge transfer in low-energy Mn+H and…

Solar and Stellar Astrophysics · Physics 2020-05-13 Jon Grumer , Paul S. Barklem

Context. In dffuse interstellar clouds the excitation temperature derived from the lowest levels of H$^+_3$ is systematically lower than that derived from H2. The differences may be attributed to the lack of state-specific formation and…

An overview of quantum-mechanical methods to generate cross-section data for electron collisions with atoms and molecules is presented. Particular emphasis is placed on the time-independent close-coupling approach, since it is particularly…

Plasma Physics · Physics 2016-10-21 Klaus Bartschat , Jonathan Tennyson , Oleg Zatsarinny

Cross sections and rate coefficients for rovibronic excitation of the CH$^+$ ion by electron impact and dissociative recombination of CH$^+$ with electrons are evaluated using a theoretical approach combining an R-matrix method and…

Astrophysics of Galaxies · Physics 2025-11-25 Joshua Forer , Dávid Hvizdoš , Mehdi Ayouz , Chris H. Greene , Viatcheslav Kokoouline

Quantum thermometry exploits the high level of control in coherent devices to offer enhanced precision for temperature estimation. This highlights the need for constructing concrete estimation strategies. Of particular importance is…

Quantum Physics · Physics 2022-02-02 Gabriel O. Alves , Gabriel T. Landi

We present the first accurate rate coefficients for the rotational excitation of CO by H2O in the kinetic temperature range 5-100 K. The statistical adiabatic channel method (SACM) is combined with a high-level rigid-rotor CO-H2O…

Earth and Planetary Astrophysics · Physics 2020-02-13 A. Faure , F. Lique , J. Loreau

Universal collision rate constants are calculated for ultracold collisions of two like bosonic or fermionic heteronuclear alkali-metal dimers involving the species Li, Na, K, Rb, or Cs. Universal collisions are those for which the short…

Chemical Physics · Physics 2017-09-13 Paul S. Julienne , Thomas M. Hanna , Zbigniew Idziaszek

The softness of elastic atomic collisions, defined as the average number of collisions each atom undergoes until its energy decorrelates significantly, can have a considerable effect on the decay dynamics of atomic coherence. In this paper…

Atomic Physics · Physics 2017-09-27 Jonathan Coslovsky , Gadi Afek , Alexander Mil , Ido Almog , Nir Davidson

The calculation of the molecular column density from molecular spectral (rotational or ro-vibrational) transition measurements is one of the most basic quantities derived from molecular spectroscopy. Starting from first principles where we…

Instrumentation and Methods for Astrophysics · Physics 2017-04-10 Jeffrey G. Mangum , Yancy L. Shirley

Collisions between ultracold calcium monohydroxide (CaOH) molecules are realized and studied. Inelastic collision rate constants are measured for CaOH prepared in ground and excited vibrational states, and the electric field dependence of…