title: Size-dependent ligand layer dynamics in semiconductor nanocrystals probed by anisotropy measurements.
abstract: Colloidal semiconductor nanocrystals (NC) have reached a high level of synthetic control allowing the tuning of their properties, and their use in various applications. However, the surface of NCs and in particular their size-dependent capping organic ligand behavior, which play an important role in the NC synthesis, dispersibility, and optoelectronic properties, is still not well understood. We study the size-dependent properties of the ligand shell on the surface of NCs, by embedding surface bound dyes as a probe within the ligand shell. The reorientation times for these dyes show a linear dependence on the NC surface curvature indicating size-dependent change in viscosity, which is related to a change in the density of the ligand layer because of the geometry of the surface, a unique feature of NCs. Understanding the properties of the ligand shell will allow rational design of the surface to achieve the desired properties, providing an additional important knob for tuning their functionality.
authors.affiliation: Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904 (Israel).
authors.forename: Ido
authors.initials: I
authors.lastname: Hadar
authors.affiliation: Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904 (Israel).
authors.forename: Tsafrir
authors.initials: T
authors.lastname: Abir
authors.affiliation: Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904 (Israel).
authors.forename: Shira
authors.initials: S
authors.lastname: Halivni
authors.affiliation: Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904 (Israel).
authors.forename: Adam
authors.initials: A
authors.lastname: Faust
authors.affiliation: Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 91904 (Israel). uri.banin@mail.huji.ac.il.
authors.forename: Uri
authors.initials: U
authors.lastname: Banin
mesh_terms: D016880:Anisotropy; D008024:Ligands; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D008024:Ligands
keywords: fluorescence spectroscopy; nanocrystals; nanotechnology; polarized spectroscopy; surface chemistry