scholarly journals Collision-Induced Absorption by Supermolecular Complexes from a New Potential Energy and Induced Dipole Surface, Suited for Calculations up to Thousands of Kelvin

2010 ◽  
Author(s):  
Martin Abel ◽  
Lothar Frommhold ◽  
Fei Wang ◽  
Magnus Gustafsson ◽  
Xiaoping Li ◽  
...  
Keyword(s):  
Potential Energy ◽  
Induced Absorption ◽  
Induced Dipole

Lineshapes and dipole moments in collision-induced absorption

1981 ◽  
Vol 59 (10) ◽  
pp. 1544-1554 ◽  
Author(s):  
George Birnbaum ◽  
Michael S. Brown ◽  
Lothar Frommhold
Keyword(s):  
Dipole Moment ◽  
Dipole Moments ◽  
Empirical Models ◽  
Fundamental Theory ◽  
Potential Models ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Substantial Error ◽  
Argon Mixture ◽  
Helium Neon

Wave mechanical lineshapes of collision-induced absorption spectra are computed for binary mixtures of argon with helium, neon, and krypton using theoretical dipole moments as input. Comparison with measured spectra shows satisfactory agreement except for the neon–argon mixture, for which either theory or measurement is seen to be in substantial error. Empirical models of the collision-induced dipole moment which reproduce the experimental spectra more closely than the fundamental theory are also given. Best agreement between computed and experimental lineshapes is obtained when potential models which are accurate in the repulsive region are used.

Spectral lineshapes of collision-induced absorption (CIA) using isotropic intermolecular potential for N2-CH4

2021 ◽  
Vol 21 (4) ◽  
pp. 1063-1078
Author(s):  
M.S.A. El-Kader ◽  
G. Maroulis ◽  
T. Bancewicz
Keyword(s):  
Potential Model ◽  
Dipole Moments ◽  
Molecular Nitrogen ◽  
Intermolecular Potential ◽  
Gaseous Mixtures ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Different Temperatures ◽  
Experimental Absorption ◽  
Good Agreement

Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures are computed for gaseous mixtures of molecular nitrogen and methane using theoretical values for the induced dipole moments and intermolecular potential as input. Comparison with theoretical absorption spectra shows satisfactory agreement. An empirical model of the dipole moment which reproduces the experimental spectra and the first three spectral moments more closely than the fundamental theory, is also presented. Good agreement between computed and experimental absorption lineshapes is obtained when a potential model which is constructed from the thermophysical and transport properties is used.

Fitting potential energy and induced dipole surfaces of the van der Waals complex CH4-N2 using non-product quadrature grids

2021 ◽  
Author(s):  
Artem Finenko ◽  
Daniil N. Chistikov ◽  
Yulia N. Kalugina ◽  
Eamon K. Conway ◽  
Iouli Gordon
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Van Der Waals ◽  
Extensive Study ◽  
Rigid Rotor ◽  
Van Der Waals Complex ◽  
Induced Dipole

We present an extensive study of the five-dimensional potential energy and induced dipole surfaces of the CH4-N2 complex assuming rigid-rotor approximation. Within the supermolecular approach, ab initio calculations of the...

Moment analysis in collision-induced absorption: Determination of a single parameter empirical model for the induced dipole moment of He-Ar gas mixtures

2021 ◽  
pp. 1-16
Author(s):  
M.S.A. El-Kader ◽  
G. Maroulis
Keyword(s):  
Dipole Moment ◽  
Empirical Model ◽  
Adjustable Parameter ◽  
Classical Physics ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Absorption Determination ◽  
Ar Gas ◽  
Good Agreement

We present a method for the construction of a one-adjustable-parameter empirical model for the induced dipole moment. The method is based on classical physics principles and relies on the first three spectral moments of the collision-induced absorption spectra at various temperatures and new interaction potentials. In this work it is applied to the spectra of He-Ar mixtures. Our values are in good agreement with the available ab initio data. The profiles calculated with these models at various temperatures are in excellent agreement with experiment.

scholarly journals Probing the rate-determining region of the potential energy surface for a prototypical ion–molecule reaction

2018 ◽  
Vol 376 (2115) ◽  
pp. 20170146 ◽  
Author(s):  
Changjian Xie ◽  
Xinguo Liu ◽  
Brendan C. Sweeny ◽  
Thomas M. Miller ◽  
Shaun G. Ard ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Classical Trajectory ◽  
Rate Coefficients ◽  
Molecule Reaction ◽  
Induced Dipole ◽  
Phase Space Theory ◽  
Selected Ion Flow Tube ◽  
High Level

We report a joint experimental–theoretical study of the F –  + HCl → HF + Cl − reaction kinetics. The experimental measurement of the rate coefficient at several temperatures was made using the selected ion flow tube method. Theoretical rate coefficients are calculated using the quasi-classical trajectory method on a newly developed global potential energy surface, obtained by fitting a large number of high-level ab initio points with augmentation of long-range electrostatic terms. In addition to good agreement between experiment and theory, analyses suggest that the ion–molecule reaction rate is significantly affected by shorter-range interactions, in addition to the traditionally recognized ion–dipole and ion–induced dipole terms. Furthermore, the statistical nature of the reaction is assessed by comparing the measured and calculated HF product vibrational state distributions to that predicted by the phase space theory. This article is part of the theme issue ‘Modern theoretical chemistry’.

scholarly journals Comparison of the Calculated Collision-Induced Absorption Spectra by Dense Hydrogen-Helium, Deuterium-Helium, and Tritium-Helium Gas Mixtures

2011 ◽  
Vol 2011 ◽  
pp. 1-3 ◽  
Author(s):  
Martin Abel ◽  
Lothar Frommhold ◽  
Xiaoping Li ◽  
K. L. C. Hunt
Keyword(s):  
Absorption Spectra ◽  
Energy Surface ◽  
Hydrogen Isotopes ◽  
Laboratory Measurements ◽  
Molecular Scattering ◽  
Induced Absorption ◽  
Induced Dipole ◽  
Scattering Wave ◽  
Helium Gas ◽  
Collisional Dynamics

We have recently determined the induced dipole surface (IDS) and potential energy surface (PES) of collisional H2-He complexes. We have used these surfaces to compute the binary collision-induced absorption spectra of H2 molecules interacting with He atoms and of D2 molecules interacting with He atoms. Here we extend these calculations to the case of T2 molecules interacting with He atoms. Whereas the electronic structure of X2-He is virtually the same for all hydrogen isotopes X = H, D, or T, the collisional dynamics and molecular scattering wave functions are different for the different collisional pairs. We have calculated spectra up to a temperature of 9000 K and frequencies up to 20,000 cm−1. Here we compare the calculated collision-induced absorption spectra for the different hydrogen isotopes. While we have observed reasonable agreement between our calculations and laboratory measurements for the collisional H2-He and D2-He complexes, there are no laboratory measurements for T2-He collisional complexes, and one must rely on the fundamental theory, supported by the agreement between theory and experiment for the other isotopes.

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