title: Fluorescence behavior of cysteine-mediated Ag@CdS nanocolloids.
abstract: Ag@CdS quantum dots were synthesized by a colloidal method. CdS nanoparticles stabilized by L-cysteine were doped with varying silver concentrations. Ag@CdS nanoparticles were characterized by UV-visible spectroscopy, steady-state and time-resolved fluorescence, X-ray diffraction, Fourier transform infrared resonance (FTIR), and transmission electron microscopy. The effect of dopant concentration and effect of aging of Ag@CdS colloids were studied. At low silver content, emission was found to enhance, while at high silver content, emission quenching was observed after aging. Ag-CdS nanocolloids exhibited multiexponential decay with tau2 being a long-lived component. X-ray diffraction spectra of as prepared samples indicated that silver occupies an interstitial position, while for annealed samples, Ag+ ions get oxidized to Ag2+ and substituted for Cd2+ in the CdS lattice. FTIR studies have shown that cysteine acts as a monodentate ligand for cadmium and silver for as-prepared sample, whereas it acts as a tridentate ligand for annealed samples toward silver. Transmission electron microscopy of as-prepared samples showed spherical-shaped composites with a uniform layer of capping molecules.
authors.affiliation: Department of Chemistry, University of Pune, Pune 411007, India.
authors.forename: Priya
authors.initials: P
authors.lastname: Thakur
authors.forename: Satyawati S
authors.initials: SS
authors.lastname: Joshi
authors.forename: Sudhir
authors.initials: S
authors.lastname: Kapoor
authors.forename: Tulsi
authors.initials: T
authors.lastname: Mukherjee
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D005453:Fluorescence; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D011789:Quantum Theory; D012834:Silver / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013440:Sulfides / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D003102:Colloids; D013440:Sulfides; C034939:cadmium sulfide; D012834:Silver; D003545:Cysteine