title: Structural phase behavior and vibrational spectroscopic studies of biofunctionalized CdS nanoparticles.
abstract: Biomodified CdS nanoparticles were synthesized using l-cysteine as a capping agent in the colloidal state as a function of pH. The role of pH on the size and structure of CdS nanoparticles was investigated in detail. At pH 7.4 and 9.1, X-ray diffraction spectra of as prepared samples showed the presence of a mixture of cubic and hexagonal phases while cubic phase was formed at pH 11.2. A gradual transition to the hexagonal phase was observed for refluxed samples at pH 9.1 and 11.2. Whereas, at pH 7.4, the sample remains in a mixture of cubic and hexagonal phase even after refluxing. The particle size of as prepared samples was about 2 nm, and for refluxed samples the size increased up to 10 nm. The binding of cadmium through thiol group is evidenced by infrared spectra. An intense band due to C-C-N vibration was observed after 24 h of reflux. The formation of a specific molecular cluster determines the growth of a particular phase. Transmission electron microscopy (TEM) studies support the X-ray diffraction (XRD) studies and exhibit well separated spherical particles while refluxed samples show clustering.
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; D006863:Hydrogen-Ion Concentration; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D044367:Phase Transition; D010984:Platinum / Q000737:chemistry; D013057:Spectrum Analysis; D013440:Sulfides / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D019187:Cadmium Compounds; D003102:Colloids; D013440:Sulfides; C034939:cadmium sulfide; D010984:Platinum; D003545:Cysteine