title: Role of Entropy in the Expulsion of Dopants from Optically Trapped Colloidal Assemblies.
abstract: Controlling an assembly of colloidal particles under external forces can be helpful in developing soft nanomaterials with novel functionalities. How external impurities organize within such confined systems is of fundamental and technological interest, especially when the system sizes are so small that even a single dopant can interact with an appreciable fraction of the system. To address this question, we use a defocused laser beam to form two-dimensional colloidal crystallites containing foreign dopants. Our studies reveal a surprising position dependence in the fate of dopants getting either spontaneously expelled or permanently internalized within the crystallite. This phenomenon arises due to the subtle interplay between the effects of external confinement and the role of entropy in the thermodynamics of small assemblies of interacting particles.
authors.affiliation: Department of Physics, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Hreedish
authors.initials: H
authors.lastname: Kakoty
authors.affiliation: Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Rajarshi
authors.initials: R
authors.lastname: Banerjee
authors.affiliation: Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Chandan
authors.initials: C
authors.lastname: Dasgupta
authors.affiliation: Department of Physics, Indian Institute of Science, Bangalore 560012, India.|Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India.|Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Ambarish
authors.initials: A
authors.lastname: Ghosh