Polarization induced control of optical trap potentials in binary liquids

Area of Science:

• Physics
• Physical Chemistry
• Materials Science

Background:

• Optical trapping utilizes laser beams to manipulate microscopic particles.
• Inherent trapping potential asymmetry (ITPA) arises from laser focal volume intensity distribution.
• Binary liquid mixtures exhibit complex microrheological properties due to molecular interactions.

Purpose of the Study:

• To demonstrate control of optical trapping potential landscapes using binary liquid mixtures.
• To investigate the modification and removal of ITPA by binary liquid mixtures.
• To explore the influence of frictional forces (FF) on trapped particle Brownian motion.

Main Methods:

• Femtosecond optical tweezers experiments were employed.
• The fluctuation-dissipation theorem was used to determine trapping potential topography.
• Brownian motion analysis quantified frictional forces in binary mixtures.

Main Results:

• Binary liquid mixtures effectively modify the optical trapping potential landscape.
• Water-alcohol mixtures showed nonlinear microrheological properties linked to cluster formation.
• Minimal trapping asymmetry was observed at approximately 30% methanol in water, correlating with enhanced hydrogen bonding and viscosity.

Conclusions:

• Control over optical trapping potential is achievable by tuning binary liquid mixture composition.
• Extended hydrogen bonding in specific binary mixtures significantly influences frictional forces and trapping anisotropy.
• The study highlights the interplay between solvent properties, frictional forces, and optical trapping dynamics.