| Autor: |
Golding, Brage, McCann, Lowell I., Dykman, Mark I. |
| Předmět: |
|
| Zdroj: |
AIP Conference Proceedings; 2000, Vol. 502 Issue 1, p34, 8p, 1 Diagram, 4 Graphs |
| Abstrakt: |
The concept of activated escape from a metastable state provides the basis for interpreting a multitude of processes that appear in physics, chemistry, and biology. Examples are diffusion in solids, fluctuations in superconducting junctions, chemical reactions, and protein folding. Quite recently, we have developed methods using light to examine the behavior of a single dielectric particle confined by optical gradient forces. These techniques allow us to tailor the trapping potential in a highly controllable way so that a variety of interesting configurations can be examined. With two independent optical beams, we have created double-well potentials and mapped their three-dimensional structure. This has allowed us to put Kramers’ theory of thermally activated transitions to a careful experimental test. By modulating the optical intensity, we can also examine the time scales on which the system falls out of equilibrium. By suitable design of the modulation function, the spatio-temporal symmetry of an otherwise spatially symmetric system can be broken. This has allowed us to demonstrate localization of the particle as a function of a control parameter. By implication, one can now control the direction of diffusion of sub-micro particles by means of a weak external field. This result has a variety of practical implications for biological transport, separation science and crystal growth. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
