The Formation of Molecules in Three Atom Collisions using the Eikonal Approximation

Czuchaj, E.

doi:10.1515/zna-1976-1206

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…͑3͒, were taken from the work of Visticot et al 15 These empirical potentials are in reasonable agreement with approximate ab initio calculations. 21 Let qϭq 1 ,...,q N denote the coordinates of the atoms of the cluster in some fixed frame. To obtain the adiabatic potential surfaces at a given configuration q, we diagonalize the interaction U of Eqs.…”

Section: B Excited-state Interactionsmentioning

confidence: 99%

Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

Krylov

Gerber

Gaveau

et al. 1996

The Journal of Chemical Physics

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Molecular Dynamics simulations using a surface-hopping method for transitions between different electronic states are employed to study the dynamics following photoexcitation of the Ba(Ar) 125 cluster. The results are used to interpret spectroscopic experiments on large, size-distributed Ba(Ar) n clusters. The dynamics of the coupled electronic-nuclear motions in the cluster involves transitions between three potential energy surfaces, corresponding to the nearly-degenerate p-states of the excited Ba atom. Ejection of excited Ba atoms, adsorbed on the surface of the cluster, can take place. The focus in comparing theory and experiment is on the emission spectrum from the excited clusters, on the polarization of this radiation, and on the polarization of light emitted by excited Ba atoms ejected from the cluster. Based on the good agreement found between theory and experiment, a comprehensive picture of the excited state dynamics is given. It is found that upon excitation, energy is rapidly redistributed in the cluster and no direct ejection of Ba occurs. Electronic relaxation to the lowest P-state occurs, and the latter dominates the cluster emission spectrum and polarization. The electronic state relaxation is mostly complete within tՇ10 ps. Ejection of Ba atoms occurs as a rare and delayed event when a dynamical fluctuation creates a ''hot spot'' at the Ba site, with a non-adiabatic excitation to the highest electronic level. The results show the feasibility of near-quantitative understanding of non-adiabatic processes in large clusters.

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Section: B Excited-state Interactionsmentioning

confidence: 99%

Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

Krylov

Gerber

Gaveau

et al. 1996

The Journal of Chemical Physics

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“…25 It is worth emphasizing again that Eq. ͑15͒ does not define a potential in a Born-Oppenheimer sense as it contains an electronic degree of freedom.…”

Section: Systems and Interactionsmentioning

confidence: 99%

Quantum dynamics simulations of nonadiabatic processes in many-atom systems: Photoexcited Ba(Ar)10 and Ba(Ar)20 clusters

Jungwirth

Gerber

1996

The Journal of Chemical Physics

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Semiclassical molecular dynamics simulations of lowtemperature clusters: Applications to (Ar)13; (Ne)13; (H2O) n , n=2,3,5Quantum simulations are reported for the dynamics following the photoexcitation Ba͑ 1 S͒→Ba͑ 1 P͒ in Ba͑Ar͒ 10 and Ba͑Ar͒ 20 clusters. The evolution in time is studied in a framework that treats quantum-mechanically all the coupled degrees of freedom. The focus is on the role of nonadiabatic transitions between the three adiabatic surfaces corresponding to the P states of the Ba atom. The time scales of electronic relaxation and of electronic depolarization ͑orbital reorientation͒ are computed, and the competition between adiabatic and nonadiabatic effects is assessed. The calculations are carried out by a new scheme that extends the recent classically based separable potential method. Semiclassical surface-hopping simulations are used to produce effective single-mode potentials on which nuclear ''orbitals'' are then generated. The full wave packet is constructed from the electronic states involved, and from these nuclear wave functions. Among the main results we find that nonadiabatic transitions become appreciable around 1 ps after photoexcitation, and they are stronger in the smaller cluster. Comparing Tully's semiclassical method with the quantum simulations, good qualitative agreement is found. Quantitatively, the semiclassical predictions for the electronic states branching rations deviate from the quantum results roughly by a factor of 2 after 1 ps. In the smaller cluster direct dissociation of the Ba atom dominates over energy redistribution within the cluster, the opposite being true for the large system. This example demonstrates the feasibility of quantum simulations of nonadiabatic processes in large systems with the new method.

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“…Ab initio calculations of Cd 2 interatomic potentials were carried out by Czuchaj and co-workers without spin−orbit coupling. The spin−orbit coupling was taken into consideration by Czuchaj, and Czuchaj and Krośnicki in two latter calculations. In the very weakly bound ground state of the group-12 homoatomic molecules (Zn 2 , Cd 2 , Hg 2 ), the long-range interaction is dominated by pure dispersion forces as expected from a simple consideration of the closed-shell atomic configurations .…”

Section: Theoretical Calculationsmentioning

confidence: 99%

Potentials of the D¹0_u⁺ (6¹S₀) and F³1_u(6³P₂) Electronic Rydberg States of Cd₂ from ab Initio Calculations and Laser-Induced Fluorescence Excitation Spectra

et al. 2011

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The method of supersonic free-jet expansion beam combined with techniques of laser spectroscopy was used in an investigation of vibronic and isotopic structures in the D¹0(u)⁺ (6¹S₀) and F³1(u)(6³P₂) electronic energy Rydberg states of Cd₂. Laser-induced fluorescence excitation spectra recorded using the D¹0(u)⁺ ← X¹0(g)⁺(5¹S₀) and F³1(u) ← X¹0(g)⁺ transitions in the region of 206-218 nm provided spectroscopic characteristics of the excited states and allowed constructing of their intratomic potentials. Isotopic structures recorded in the (υ',υ'') bands of the D¹0(u)⁺ ← X¹0(g)⁺ transition were used in determination of the D¹0(u)⁺ state vibrational characteristics (ω'(e)x'(e), ω'(e)x'(e)) and υ' assignment. The ν(0,0) recorded directly in the F³1(u) ← X¹0(g)⁺ transition enabled determination of the bottom of the F³1(u) state potential well. Valence ab initio calculations of Cd₂ interatomic potentials were performed with relativistic and spin-orbit effects taken into account. The experimental results were compared with results of the ab initio calculations. A free-jet expansion of Cd₂ as a source of entangled atoms for a test of Bell's inequality was analyzed.

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The Formation of Molecules in Three Atom Collisions using the Eikonal Approximation

Cited by 3 publications

References 9 publications

Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

Quantum dynamics simulations of nonadiabatic processes in many-atom systems: Photoexcited Ba(Ar)10 and Ba(Ar)20 clusters

Potentials of the D¹0_u⁺ (6¹S₀) and F³1_u(6³P₂) Electronic Rydberg States of Cd₂ from ab Initio Calculations and Laser-Induced Fluorescence Excitation Spectra

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The Formation of Molecules in Three Atom Collisions using the Eikonal Approximation

Cited by 3 publications

References 9 publications

Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

Quantum dynamics simulations of nonadiabatic processes in many-atom systems: Photoexcited Ba(Ar)10 and Ba(Ar)20 clusters

Potentials of the D10u+ (61S0) and F31u(63P2) Electronic Rydberg States of Cd2 from ab Initio Calculations and Laser-Induced Fluorescence Excitation Spectra

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Potentials of the D¹0_u⁺ (6¹S₀) and F³1_u(6³P₂) Electronic Rydberg States of Cd₂ from ab Initio Calculations and Laser-Induced Fluorescence Excitation Spectra