Physical Society Colloquium

Trapping and coherent control of molecules in liquids at room temperature

Adam Cohen

Department of Chemistry & Chemical Biology and Department of Physics
Harvard University

Can we apply ideas from atomic physics to control molecules in liquids at room temperature? In spite of the differences between a cold vacuum and a warm liquid, a surprising amount can be done. I will present two examples of molecular control in liquids. The Anti-Brownian Electrokinetic trap (ABEL trap) is a machine that can trap and manipulate individual fluorescent molecules in solution. The ABEL trap uses photon-by-photon particle tracking and real time electrokinetic feedback to cancel the Brownian motion of a single molecule. The ABEL trap has been used to trap single molecules of DNA, proteins, and virus particles. In the second example, I will discuss the possibilities for very weak magnetic fields to affect the outcome of a chemical reaction through the effect of the field on the coherent spin dynamics. I will show that magnetic interactions five orders of magnitude weaker than thermal energy can have big effects on molecular dynamics.