Direct Visualization of Barrier Crossing Dynamics in a Driven Optical Matter System
| Autor: | Norbert F. Scherer, Patrick Figliozzi, Curtis W. Peterson, Stuart A. Rice |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Chemical Physics (physics.chem-ph)
Physics Cantilever Atoms in molecules General Engineering FOS: Physical sciences General Physics and Astronomy Non-equilibrium thermodynamics 02 engineering and technology Condensed Matter - Soft Condensed Matter 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics Transducer Optical tweezers Position (vector) Physics - Chemical Physics 0103 physical sciences Trajectory Soft Condensed Matter (cond-mat.soft) General Materials Science 010306 general physics 0210 nano-technology Event (particle physics) |
| Zdroj: | ACS Nano. 12:5168-5175 |
| ISSN: | 1936-086X 1936-0851 |
| DOI: | 10.1021/acsnano.8b02012 |
| Popis: | A major impediment to a more complete understanding of barrier crossing and other single-molecule processes is the inability to directly visualize the trajectories and dynamics of atoms and molecules in reactions. Rather, the kinetics are inferred from ensemble measurements or the position of a transducer ( e. g., an AFM cantilever) as a surrogate variable. Direct visualization is highly desirable. Here, we achieve the direct measurement of barrier crossing trajectories by using optical microscopy to observe position and orientation changes of pairs of Ag nanoparticles, i. e. passing events, in an optical ring trap. A two-step mechanism similar to a bimolecular exchange reaction or the Michaelis-Menten scheme is revealed by analysis that combines detailed knowledge of each trajectory, a statistically significant number of repetitions of the passing events, and the driving force dependence of the process. We find that while the total event rate increases with driving force, this increase is due to an increase in the rate of encounters. There is no drive force dependence on the rate of barrier crossing because the key motion for the process involves a random (thermal) radial fluctuation of one particle allowing the other to pass. This simple experiment can readily be extended to study more complex barrier crossing processes by replacing the spherical metal nanoparticles with anisotropic ones or by creating more intricate optical trapping potentials. |
| Databáze: | OpenAIRE |
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