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Biological and Chemical Physics Commons

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Full-Text Articles in Biological and Chemical Physics

Collisional Dynamics Of Bi2 A(0U+). I. Quantum-Resolved Vibrational Energy Transfer For V′=0–4, Robert E. Franklin, Glen P. Perram Oct 1999

Collisional Dynamics Of Bi2 A(0U+). I. Quantum-Resolved Vibrational Energy Transfer For V′=0–4, Robert E. Franklin, Glen P. Perram

Faculty Publications

Vibrational-to-translational energy transfer between the lowest vibrational levels (v′=0–4) of the A(0+u) state of Bi2 has been investigated using spectrally resolved, laser-induced fluorescence techniques. The small vibrational spacing (ω′e≃132 cm−1) leads to highly nonadiabatic conditions, particularly for the Bi2(A)–He collision pair. However, the Δv=−1 transition probabilities for collisions with the rare gases range from 0.75% to 1.75% per collision, considerably lower than would be anticipated from standard vibrational energy transfer theory. Multiquantum (Δv′=±2) transfer rates are low, consistent with the low anharmonicity of the A(0+u) state. The rates for …


Cumulative Reaction Probability In Terms Of Reactant-Product Wave Packet Correlation Functions, Sophya V. Garashchuk, D. J. Tannor Jan 1999

Cumulative Reaction Probability In Terms Of Reactant-Product Wave Packet Correlation Functions, Sophya V. Garashchuk, D. J. Tannor

Faculty Publications

We present new expressions for the cumulative reaction probability (N(E)), cast in terms of time-correlation functions of reactant and product wave packets. The derivation begins with a standard trace expression for the cumulative reaction probability, expressed in terms of the reactive scattering matrix elements in an asymptotic internal basis. By combining the property of invariance of the trace with a wave packet correlation function formulation of reactive scattering, we obtain an expression for N(E) in terms of the correlation matrices of incoming and outgoing wave packets which are arbitrary in the internal coordinates. This formulation, like other recent formulations of …


Semiclassical Calculation Of Cumulative Reaction Probabilities, Sophya V. Garashchuk, D. J. Tannor Jan 1999

Semiclassical Calculation Of Cumulative Reaction Probabilities, Sophya V. Garashchuk, D. J. Tannor

Faculty Publications

Calculation of chemical reaction rates lies at the very core of theoretical chemistry. The essential dynamical quantity which determines the reaction rate is the energy-dependent cumulative reaction probability, N(E), whose Boltzmann average gives the thermal rate constant, k(T). Converged quantum mechanical calculations of N(E) remain a challenge even for three- and four-atom systems, and a longstanding goal of theoreticians has been to calculate N(E) accurately and efficiently using semiclassical methods. In this article we present a variety of methods for achieving this goal, by combining semiclassical initial value …