title: Fluorescence quenching of CdS quantum dots by 4-azetidinyl-7-nitrobenz-2-oxa-1,3-diazole: a mechanistic study.
abstract: Fluorescence quenching of CdS quantum dots (QDs) by 4-azetidinyl-7-nitrobenz-2-oxa-1,3-diazole (NBD), where the two quenching partners satisfy the spectral overlap criterion necessary for Förster resonance energy transfer (FRET), is studied by steady-state and time-resolved fluorescence techniques. The fluorescence quenching of the QDs is accompanied by an enhancement of the acceptor fluorescence and a reduction of the average fluorescence lifetime of the donor. Even though these observations are suggestive of a dynamic energy transfer process, it is shown that the quenching actually proceeds through a static interaction between the quenching partners and is probably mediated by charge-transfer interactions. The bimolecular quenching rate constant estimated from the Stern-Volmer plot of the fluorescence intensities, is found to be exceptionally high and unrealistic for the dynamic quenching process. Hence, a kinetic model is employed for the estimation of actual quencher/QD ratio dependent exciton quenching rate constants of the fluorescence quenching of CdS by NBD. The present results point to the need for a deeper analysis of the experimental quenching data to avoid erroneous conclusions.
authors: School of Chemistry, University of Hyderabad, Gachi Bowli, Hyderabad 500046, India.
authors: Kotni
authors: K
authors: Santhosh
authors: Satyajit
authors: S
authors: Patra
authors: S
authors: S
authors: Soumya
authors: Dinesh Chandra
authors: DC
authors: Khara
authors: Anunay
authors: A
authors: Samanta
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D010069:Oxadiazoles / Q000737:chemistry*; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence; D013440:Sulfides / Q000737:chemistry*; D013499:Surface Properties
chemical_list: C570802:4-azetidinyl-7-nitrobenz-2-oxa-1,3-diazole; D019187:Cadmium Compounds; D010069:Oxadiazoles; D013440:Sulfides; C034939:cadmium sulfide