Determination of the Dipole Geometry of Fluorescent Nanoparticles Using Polarized Excitation and Emission Analysis

Jianan Li, Ka Cheung Kwok, Nai Ho CHEUNG*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

Abstract

We demonstrate that the geometries of the absorption dipole 1/4ab and emission dipole 1/4em of nano-emitters such as quantum dots can be determined simultaneously by far-field polarimetry. The method involves plotting the emission polarization ratio against the absorption polarization ratio of single nano-emitters. Using Monte Carlo simulation, we show that these plots depend sensitively on the aspect ratio of the dipole shape. For example, the so-called 3D-2D dipole combination, that is, 1/4ab of radius ratio 1:1:1 and 1/4em of ratio 1:1:0, would give rise to a vertical line plot. Polarization ratios of commercial cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dots are measured and plotted. The empirical data points are best-fitted to yield 1/4ab of radius ratio 1:1:0.28 and 1/4em of ratio 1:1:0.

Original languageEnglish
Pages (from-to)302-311
Number of pages10
JournalApplied Spectroscopy
Volume70
Issue number2
DOIs
Publication statusPublished - 1 Feb 2016

Scopus Subject Areas

  • Instrumentation
  • Spectroscopy

User-Defined Keywords

  • Dipole geometry
  • polarimetry
  • quantum dots

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