title: Confirmation of disordered structure of ultrasmall CdSe nanoparticles from X-ray atomic pair distribution function analysis.
abstract: The atomic pair distribution function (PDF) analysis of X-ray powder diffraction data has been used to study the structure of small and ultra-small CdSe nanoparticles. A method is described that uses a wurtzite and zinc-blende mixed phase model to account for stacking faults in CdSe particles. The mixed-phase model successfully describes the structure of nanoparticles larger than 2 nm yielding a stacking fault density of about 30%. However, for ultrasmall nanoparticles smaller than 2 nm, the models cannot fit the experimental PDF showing that the structure is significantly modified from that of larger particles and the bulk. The observation of a significant change in the average structure at ultra-small size is likely to explain the unusual properties of the ultrasmall particles such as their white light emitting ability.
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA.
authors.forename: Xiaohao
authors.initials: X
authors.lastname: Yang
authors.forename: Ahmad S
authors.initials: AS
authors.lastname: Masadeh
authors.forename: James R
authors.initials: JR
authors.lastname: McBride
authors.forename: Emil S
authors.initials: ES
authors.lastname: Božin
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Rosenthal
authors.forename: Simon J L
authors.initials: SJ
authors.lastname: Billinge
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D033362:Powder Diffraction; D018036:Selenium Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; C058667:cadmium selenide