scholarly journals Potential Energy Surfaces for Unsaturated Hydrocarbons from Crossed Molecular Beams

1997 ◽  
Vol 50 (3) ◽  
pp. 683
Author(s):  
K. P. Stevenson ◽  
J. D. Close ◽  
P. L. Muiño ◽  
R. O. Watts
Keyword(s):  
Potential Energy ◽  
Cross Sections ◽  
Potential Energy Surfaces ◽  
Interaction Strength ◽  
Molecular Beams ◽  
Unsaturated Hydrocarbon ◽  
Atmospheric Gases ◽  
Weakly Bound ◽  
Energy Surfaces ◽  
Scattering Cross Sections

The total differential scattering cross sections for several important unsaturated hydrocarbon molecules with common atmospheric gases were measured in a crossed molecular beam apparatus. The experiments show quantum interferences which relate to potential energy surface parameters, such as the well depth and radial minimum. The damping of the quantum features, over contributions from experimental resolutions, provides information on the angular and radial anisotropies present in the potential energy surfaces. We have investigated two areas: (1) the role of the probe partner in determining the interaction strength for a given hydrocarbon target, and (2) the effect of increasing the overall length of the hydrocarbon molecule for a fixed probe. By comparing results for a class of scattering systems, we can identify chemical and physical trends that determine the van der Waals potential energy surfaces of larger molecules. We expect these results to aid in the prediction and interpretation of complementary experimental measurements on the high resolution infrared spectroscopy of weakly bound complexes.

Differential Scattering Cross Sections for HeCl2, NeCl2, and ArCl2:  Multiproperty Fits of the Potential Energy Surfaces

1997 ◽  
Vol 101 (36) ◽  
pp. 6528-6537 ◽  
Author(s):  
Andreas Rohrbacher ◽  
Kenneth C. Janda ◽  
Laura Beneventi ◽  
Piergiorgio Casavecchia ◽  
Gian Gualberto Volpi
Keyword(s):  
Potential Energy ◽  
Cross Sections ◽  
Potential Energy Surfaces ◽  
Scattering Cross ◽  
Energy Surfaces ◽  
Scattering Cross Sections

Symmetry-adapted perturbation theory of potential-energy surfaces for weakly bound molecular complexes

1994 ◽  
Vol 307 ◽  
pp. 135-151 ◽  
Author(s):  
Tatiana Cwiok ◽  
Bogumil Jeziorski ◽  
Wlodzimierz Kolos ◽  
Robert Moszynski ◽  
Krzysztof Szalewicz
Keyword(s):  
Perturbation Theory ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Molecular Complexes ◽  
Weakly Bound ◽  
Energy Surfaces

scholarly journals O(3P) + CO2 scattering cross-sections at superthermal collision energies for planetary aeronomy

2019 ◽  
Vol 491 (4) ◽  
pp. 5650-5659 ◽  
Author(s):  
Marko Gacesa ◽  
R J Lillis ◽  
K J Zahnle
Keyword(s):  
Cross Sections ◽  
Potential Energy Surfaces ◽  
Energy Transport ◽  
Basis Set ◽  
Planar Geometry ◽  
Rotational States ◽  
Mass Scaling ◽  
Linear Configuration ◽  
Energy Surfaces ◽  
Scattering Cross Sections

ABSTRACT We report new elastic and inelastic cross-sections for O(3P) + CO2 scattering at collision energies from 0.03 to 5 eV, of major importance to O escape from Mars, Venus, and CO2-rich atmospheres. The cross-sections were calculated from first principles using three newly constructed ab initio potential energy surfaces correlating to the lowest energy asymptote of the complex. The surfaces were restricted to a planar geometry with the CO2 molecule assumed to be in linear configuration fixed at equilibrium. Quantum-mechanical coupled-channel formalism with a large basis set was used to compute state-to-state integral and differential cross-sections for elastic and inelastic O(3P) + CO2 scattering between all pairs of rotational states of CO2 molecule. The elastic cross-sections are 35 per cent lower at 0.5 eV and more than 50 per cent lower at 4 + eV than values commonly used in studies of processes in upper and middle planetary atmospheres of Mars, Earth, Venus, and CO2-rich planets. Momentum transfer cross-sections, of interest for energy transport, were found to be proportionally lower than predicted by mass scaling.

Observation of the geometric phase effect in the H + HD → H2+ D reaction

Science ◽  
2018 ◽  
Vol 362 (6420) ◽  
pp. 1289-1293 ◽  
Author(s):  
Daofu Yuan ◽  
Yafu Guan ◽  
Wentao Chen ◽  
Hailin Zhao ◽  
Shengrui Yu ◽  
...  
Keyword(s):  
Cross Sections ◽  
Geometric Phase ◽  
Potential Energy Surfaces ◽  
Molecular Beams ◽  
Conical Intersection ◽  
Molecular Systems ◽  
Quantum State Resolved ◽  
State Potential ◽  
Energy Surfaces ◽  
Angular Oscillations

Theory has established the importance of geometric phase (GP) effects in the adiabatic dynamics of molecular systems with a conical intersection connecting the ground- and excited-state potential energy surfaces, but direct observation of their manifestation in chemical reactions remains a major challenge. Here, we report a high-resolution crossed molecular beams study of the H + HD → H2+ D reaction at a collision energy slightly above the conical intersection. Velocity map ion imaging revealed fast angular oscillations in product quantum state–resolved differential cross sections in the forward scattering direction for H2products at specific rovibrational levels. The experimental results agree with adiabatic quantum dynamical calculations only when the GP effect is included.

POTENTIAL ENERGY SURFACES AND DYNAMICS OF THE EXCITED OH(A2Σ+) IN COLLISIONS WITH HE AND CO(X1Σ+)

1989 ◽  
Author(s):  
Αγγελική Βεγίρη
Keyword(s):  
Potential Energy ◽  
Cross Sections ◽  
Potential Energy Surfaces ◽  
Dynamical Behaviour ◽  
Multiple Collision ◽  
Close Coupling ◽  
Total Cross Sections ◽  
Analytical Potential ◽  
Classical Trajectories ◽  
Energy Surfaces

THE AIM OF THE WORK WAS THE THEORETICAL STUDY OF THE DYNAMICAL BEHAVIOUR OF THEEXCITED OH(A2Σ+) IN COLLISIONS WITH HE AND CO. AB INITION POTENTIAL CURVES OF HEO AND POTENTIAL ENERGY SURFACES OF HEOH FOR THE FIRST THREE STATES WERE CALCULATED. AN ANALYTICAL POTENTIAL FUNCTION FOR THE EXCITED 22A' STATE WAS PRODUCED AND CLOSE-COUPLING SPIN AVERAGED TOTAL CROSS SECTIONS WERE CALCULATED.IT WAS FOUND THAT EVEN ROTATIONAL TRANSITIONS ARE FAVOURED OVER THE ODE ONES. THE COMPUTED PARTIAL CROSS SECTIONS SHOWED SECONDARY MINIMA AND EXPLANATION WAS THOUGHT BY EXAMING THE APPROPRIATE CLASSICAL TRAJECTORIES. THESE FEATURES WERE ATTRIBUTED TO MULTIPLE COLLISION EFFECTS IN THE ELECTRONIC DEEXITATION OF OH(A2Σ+) IN COLLISIONS WITH GROUND STATE CO WAS STUDIED. THE CALCULATIONS CONFIRM THE EXPERIMENTALLY DEDUCED PICTURE OF A COLLISION COMPLEX FORMATION AND THUS THE DEPENDENCE OF THE QUENCHING CROSS SECTION ON THE ROTATIONAL EXCITATION OF OH(A2Σ+) AND THE COLLISION TEMPERATURE. THE STUDY OF THE DYNAMICAL BEHAVIOUR OF THE EXCITED OH WITH HE, BY RUNNING CLASSICAL TRAJECTORIES REVEALEDTHAT THE MOST IMPORTANT PATH OF THE QUENCHING IS THROUGH THE FORMATION OF THE C2V SYMMETRY COMPLEX.

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