Tailoring the escape rate of a Brownian particle by combining a vortex flow with a magnetic field

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • I. Abdoli - , Leibniz Institute of Polymer Research Dresden (Author)
  • Hartmut Löwen - , Heinrich Heine University Düsseldorf (Author)
  • J. U. Sommer - , Leibniz Institute of Polymer Research Dresden (Author)
  • A. Sharma - , Leibniz Institute of Polymer Research Dresden (Author)

Abstract

The probability per unit time for a thermally activated Brownian particle to escape over a potential well is, in general, well-described by Kramers's theory. Kramers showed that the escape time decreases exponentially with increasing barrier height. The dynamics slow down when the particle is charged and subjected to a Lorentz force due to an external magnetic field. This is evident via a rescaling of the diffusion coefficient entering as a prefactor in the Kramers's escape rate without any impact on the barrier-height-dependent exponent. Here, we show that the barrier height can be effectively changed when the charged particle is subjected to a vortex flow. While the vortex alone does not affect the mean escape time of the particle, when combined with a magnetic field, it effectively pushes the fluctuating particle either radially outside or inside depending on its sign relative to that of the magnetic field. In particular, the effective potential over which the particle escapes can be changed to a flat, a stable, and an unstable potential by tuning the signs and magnitudes of the vortex and the applied magnetic field. Notably, the last case corresponds to enhanced escape dynamics.

Details

Original languageEnglish
Article number101101
JournalJournal of Chemical Physics
Volume158
Issue number10
Publication statusPublished - 14 Mar 2023
Peer-reviewedYes
Externally publishedYes

External IDs

PubMed 36922145