| Popis: |
Thermophoresis is a phenomenon of drift motion of colloidal particles in a temperature gradient. There has been a growing interest in exploiting its potential applications in sorting, concentrating, and separation of particles and macromolecules. However, the success of such applications has been uneven because the phenomenon is difficult hard to predict quantitatively. Thermophoresis is known to be attributed by many competing for thermally driven effects, including the electroosmosis in the electric double layer, a concentration gradient of ionic species in the solvent, dispersion forces, depletion forces, and hydrogen bonding. Because the different attributes have different temporal responses, measuring their time dependence could be used to distinguish these completion attributes. This research sets out to identify different attributes by investigating the frequency dependence of the particle's drift motion in a harmonically driven temperature gradient. Measured by phoretic force spectroscopy, the results of the frequency-dependent magnitude and phase delay of the drift motion of an optically trapped particle in the harmonic temperature gradient are will be reported in this paper. |
