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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Measurement of the Hydrodynamic Radius of Quantum Dots by Fluorescence Correlation Spectroscopy Excluding Blinking

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Author(s):
de Thomaz, A. A. [1] ; Almeida, D. B. [1] ; Pelegati, V. B. [1] ; Carvalho, H. F. [2, 3] ; Cesar, C. L. [1, 3]
Total Authors: 5
Affiliation:
[1] State Univ Campinas UNICAMP, Inst Phys Gleb Wataghin, Dept Quantum Elect, BR-13083859 Sao Paulo - Brazil
[2] State Univ Campinas UNICAMP, Inst Biol, Dept Struct & Funct Biol, BR-13083865 Sao Paulo - Brazil
[3] Natl Inst Photon Appl Cell Biol INFABIC, BR-13083865 Sao Paulo - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Journal of Physical Chemistry B; v. 119, n. 11, p. 4294-4299, MAR 19 2015.
Web of Science Citations: 6
Abstract

One of the most important properties of quantum dots (QDs) is their size. Their size will determine optical properties and in a colloidal medium their range of interaction. The most common techniques used to measure QD size are transmission electron microscopy (TEM) and X-ray diffraction. However, these techniques demand the sample to be dried and under a vacuum. This way any hydrodynamic information is excluded and the preparation process may alter even the size of the QDs. Fluorescence correlation spectroscopy (FCS) is an optical technique with single molecule sensitivity capable of extracting the hydrodynamic radius (HR) of the QDs. The main drawback of FCS is the blinking phenomenon that alters the correlation function implicating in a QD apparent size smaller than it really is. In this work, we developed a method to exclude blinking of the FCS and measured the HR of colloidal QDs. We compared our results with TEM images, and the HR obtained by FCS is higher than the radius measured by TEM. We attribute this difference to the cap layer of the QD that cannot be seen in the TEM images. (AU)

FAPESP's process: 09/54164-9 - Laboratory of Multimodal Microscopy: complementary project for the creation of the main INCT-INFABiC Laboratory
Grantee:Hernandes Faustino de Carvalho
Support Opportunities: Multi-user Equipment Program