Threshold resonance effects in reactive processes

Abstract

We investigate the effect of near threshold resonances in reactive scattering at low energy. We find a general type of anomalous behavior of the cross sections, and illustrate it with a real system (H${}_2$ + Cl). For inelastic processes, the anomalous energy dependence of the total cross sections is given by $\sigma \sim {\epsilon }^{-3/2}$. The standard threshold behavior given by Wigner's law ($\sigma \sim {\epsilon }^{-1/2}$) is eventually recovered at vanishing energies, but its validity is now limited to a much narrower range of energies. The universal anomalous behavior leads to reaction rate coefficients behaving as $K\sim 1/T$ at low temperatures, instead of the expected constant rate of the Wigner regime. We also provide analytical expressions for s-wave cross sections, and discuss the implication in ultracold physics and chemistry.

5 figures

References in corpus (5)

• Theory of ultracold Fermi gases
• Observation of Quantum Effects in sub Kelvin Cold Reactions
• Feshbach resonances in ultracold atomic and molecular collisions: threshold behaviour and suppression of poles in scattering lengths
• Giant formation rates of ultracold molecules via Feshbach Optimized Photoassociation
• Interactions and dynamics in Li + Li_2 ultracold collisions

Cited by in corpus (8)

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• Jost function description of near threshold resonances for coupled-channel scattering
• Observation of Wigner cusps in a metallic carbon nanotube
• Molecular Hydrogen: a benchmark system for Near Threshold Resonances at higher partial waves
• Near-threshold scaling of resonant inelastic collisions at ultralow temperatures
• Phase-amplitude formalism for ultra-narrow shape resonances
• Resonances at very low temperature for the reaction D${}_2$+H