Fluorescence quenching of CdS quantum dots by 4-azetidinyl-7-nitrobenz-2- oxa-1,3-diazole: A mechanistic study

Kotni Santhosh, Satyajit Patra, S. Soumya, Dinesh Chandra Khara, Anunay Samanta

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

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. Fluorescence quenching of CdS quantum dots by 4-azetidinyl-7-nitrobenz-2-oxa-1,3-diazole, which shows FRET-like behaviour, is actually mediated by the static interaction of the two (see picture).

Original languageEnglish
Pages (from-to)2735-2741
Number of pages7
JournalChemPhysChem
Volume12
Issue number15
DOIs
StatePublished - 24 Oct 2011
Externally publishedYes

Keywords

  • charge transfer
  • energy transfer
  • fluorescence
  • quantum dots
  • static and dynamic quenching

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

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