title: Alloy formation at the tetrapod core/arm interface.
abstract: The nature of the interfacial structure between the core and the arms of a tetrapod quantum dot (QD) formed during the heteroepitaxial growth of a ZnS arm onto a CdSe core is not well understood but can be analyzed through the use of high-frequency electron paramagnetic resonance (HF-EPR) spectroscopy. The spectroscopic resolution at high frequency allows the presence of unique crystal fields reflecting interfacial alloying to be analyzed by incorporating Mn(II) ions as a dopant into the QD to act as an intentional EPR active spectroscopic probe. In addition, the HF-EPR can spectroscopically observe the presence of ion vacancies that are anticipated to form at the heteroepitaxial interface to accommodate structural mismatch. The HF-EPR spectra for Mn(II) are extremely sensitive to perturbations of the microenvironment due to changes in the crystal field. The HF-EPR spectra of Mn(II) in a CdSe (core)/ZnS (arm) tetrapod exhibiting wurtzite symmetry for both core and interface of the tetrapod provide clear evidence of heteroalloying at the core-arm interface and formation of intrinsic dislocations at grain boundaries. The formation of the interfacial alloy and grain boundaries reflects short-range ion migration at the heteroepitaxial layer to reduce strain energy due to the 12% lattice mismatch between the wurtzite lattices of CdSe and ZnS.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zheng
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Wang
authors.forename: Johan
authors.initials: J
authors.lastname: van Tol
authors.forename: Naresh S
authors.initials: NS
authors.lastname: Dalal
authors.forename: Geoffrey F
authors.initials: GF
authors.lastname: Strouse
mesh_terms: D000497:Alloys / Q000138:chemical synthesis*; D019187:Cadmium Compounds / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D010316:Particle Size; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000497:Alloys; D019187:Cadmium Compounds; D046911:Macromolecular Substances; D018036:Selenium Compounds; C058667:cadmium selenide