title: Probing the Interaction of Quantum Dots with Chiral Capping Molecules Using Circular Dichroism Spectroscopy.
abstract: Circular dichroism (CD) induced at exciton transitions by chiral ligands attached to single component and core/shell colloidal quantum dots (QDs) was used to study the interactions between QDs and their capping ligands. Analysis of the CD line shapes of CdSe and CdS QDs capped with l-cysteine reveals that all of the features in the complex spectra can be assigned to the different excitonic transitions. It is shown that each transition is accompanied by a derivative line shape in the CD response, indicating that the chiral ligand can split the exciton level into two new sublevels, with opposite angular momentum, even in the absence of an external magnetic field. The role of electrons and holes in this effect could be separated by experiments on various types of core/shell QDs, and it was concluded that the induced CD is likely related to interactions of the highest occupied molecular orbitals of the ligands with the holes. Hence, CD was useful for the analysis of hole level-ligand interactions in quantum semiconductor heterostructures, with promising outlook toward better general understanding the properties of the surface of such systems.
authors.affiliation: School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University , Tel Aviv 6997801, Israel.
authors.forename: Assaf
authors.initials: A
authors.lastname: Ben-Moshe
authors.affiliation: Department of Physics of Complex Systems, Weizmann Institute of Science , Rehovot 7610001, Israel.
authors.forename: Ayelet
authors.initials: A
authors.lastname: Teitelboim
authors.affiliation: Department of Physics of Complex Systems, Weizmann Institute of Science , Rehovot 7610001, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Oron
authors.affiliation: School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University , Tel Aviv 6997801, Israel.
authors.forename: Gil
authors.initials: G
authors.lastname: Markovich
keywords: Quantum dots; chiral molecules; circular dichroism; core−shell nanoparticles; nanoscale chirality