A simple zero-velocity method to determine the particle magnetic susceptibility by measuring the magnetophoretic velocity was proposed. The principle is that the magnetophoretic velocity of a particle in a liquid medium must be zero when the magnetic susceptibilities of the medium and the particle are equal, or the gravity force and the magnetophoretic force are balanced. By changing the medium magnetic susceptibility and measuring the magnetophoretic velocity of a particle, the particle magnetic susceptibility was determined from the medium magnetic susceptibility under the zero-velocity condition. The feasibility of the method was demonstrated for polystyrene particles using a Dy(III) solution in the horizontal migration mode and different organic solvents in the vertical migration mode.

The J-aggregates of the diprotonated tetraphenylporphin formed in the o/w microemulsions including 2-alkyl alcohol, Triton X-100, toluene, and sulfuric acid, exhibited an induced circular dichroism (ICD) spectra corresponding to the chirality of the alcohol. The ICD intensity remarkably depended on the concentrations of Triton X-100 and sulfuric acid as well as 2-alkyl alcohol. The results suggested the nonstoichiometric formation of the chiral conformation of the nano-J-aggregates in the microemulsion droplets.