scholarly journals Effect of isotropic collisions with neutral hydrogen on the polarization of the CN solar molecule

2019 ◽  
Vol 491 (1) ◽  
pp. 1213-1226 ◽  
Author(s):  
S Qutub ◽  
M Derouich ◽  
Y N Kalugina ◽  
H Asiri ◽  
F Lique
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Infinite Order ◽  
Neutral Hydrogen ◽  
Rate Coefficients ◽  
Sudden Approximation ◽  
Collisional Rate Coefficients ◽  
Energy Surfaces ◽  
Collisional Rate ◽  
Electronic Ground

ABSTRACT In this work, we study the solar molecule CN, which presents conspicuous profiles of scattering polarization. We start by calculating accurate potential energy surfaces for the singlet and triplet electronic ground states in order to characterize the collisions between the CN molecule in its X 2Σ state and the hydrogen in its ground state 2S. The potential energy surfaces are included in the Schrödinger equation to obtain the scattering matrix and the probabilities of collisions. Depolarizing collisional rate coefficients are computed in the framework of the infinite order sudden approximation for temperatures ranging from T = 2000 K to T= 15 000 K. We give an interpretation of the results and compare the singlet and triplet collisional rate coefficients. We show that, for typical photospheric hydrogen density (nH = 1015−1016 cm−3), the X 2Σ state of CN is partially or completely depolarized by isotropic collisions.

scholarly journals New H2O–H2O collisional rate coefficients for cometary applications

2020 ◽  
Vol 498 (4) ◽  
pp. 5489-5497 ◽  
Author(s):  
C Boursier ◽  
B Mandal ◽  
D Babikov ◽  
M L Dubernet
Keyword(s):  
Cross Sections ◽  
Potential Energy Surfaces ◽  
Rate Coefficients ◽  
Molecular Systems ◽  
Large Sets ◽  
Alternative Approach ◽  
Collisional Rate Coefficients ◽  
Energy Surfaces ◽  
Good Agreement

ABSTRACT We re-introduce a semiclassical methodology based on theories developed for the determination of broadening coefficients. We show that this simple and extremely fast methodology provides results that are in good agreement with results obtained using the more sophisticate MQCT approach. This semiclassical methodology could be an alternative approach which allows to provide large sets of collisional data for very complex molecular systems. It saves time both on the determination of potential energy surfaces and on the collisional dynamical calculations. In addition, this paper provides more complete sets of rotational de-excitation cross-sections and rate coefficients of H2O perturbed by a thermal average of water molecules. Those data can be used in the radiative transfer modelling of cometary atmospheres.

New ab initio potential energy surfaces for the ro-vibrational excitation of OH(X2Π) by He

2014 ◽  
Vol 16 (26) ◽  
pp. 13500-13507 ◽  
Author(s):  
Yulia Kalugina ◽  
François Lique ◽  
Sarantos Marinakis
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Cross Sections ◽  
Differential Cross ◽  
Potential Energy Surfaces ◽  
Vibrational Excitation ◽  
Three Dimensional ◽  
Rate Coefficients ◽  
Differential Cross Sections ◽  
Energy Surfaces

A new, three-dimensional potential energy is presented. Values for integral and differential cross sections, and for inelastic rate coefficients were obtained. The results agree and significantly extend previous studies on OH(X) + He collisions.

THE PHOTODESORPTION OF NO FROM A Pt SURFACE

1994 ◽  
Vol 01 (04) ◽  
pp. 615-620 ◽  
Author(s):  
S. HARRIS ◽  
S. HOLLOWAY
Keyword(s):  
Potential Energy ◽  
Ground State ◽  
Potential Energy Surfaces ◽  
Time Dependent ◽  
Hot Electron ◽  
Sufficient Energy ◽  
Oppenheimer Approximation ◽  
Quantum Wave ◽  
Energy Surfaces ◽  
Electronic Ground

Time-dependent quantum wave packets have been used in a model calculation to investigate the photodesorption of an NO molecule from a Pt surface. A hot electron, generated in the substrate by an absorbed photon, may temporarily resonate in an unoccupied NO molecular orbital. If the electron spends enough time in the resonance, then on returning to the electronic ground state, the excited NO can acquire sufficient energy to desorb. The new aspect presented here is to treat the motion of the NO and that of the electron on an equal footing when calculating the photodesorption yield. We have not employed the Born-Oppenheimer approximation, but rather studied the dynamics on potential energy surfaces including both the NO-Pt and electron-Pt interactions.

scholarly journals Resolved fine and hyperfine state-to-state rate coefficients for the rotational transitions of C3N induced by collision with He

2021 ◽  
Author(s):  
Miguel Lara-Moreno ◽  
Thierry Stoecklin ◽  
Philippe Halvick
Keyword(s):  
Potential Energy ◽  
Infinite Order ◽  
Energy Surface ◽  
Rate Coefficients ◽  
Two Dimensional ◽  
Close Coupling ◽  
State Rate ◽  
Sudden Approximation ◽  
Hyperfine State ◽  
Fine And Hyperfine Structure

Abstract The fine and hyperfine resolved state-to-state rate coefficients for the rotational (de)excitation of C3N by collision with helium are computed. To this aim a two dimensional potential energy surface is calculated for this system. The recoupling method is used to obtain the fine and hyperfine structure resolved rate coefficients from spin-free Close Coupling calculations. These results are compared with those given by the Infinite Order Sudden Approximation and the M-randomizing Limit. General propensity rules for the transitions are also found and analyzed.

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