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The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 10 Issue 4 (2005) pp 269-282
DOI 10.1333/s00897050912a

Demonstration of a Low-Cost, Single-Molecule Capable, Multimode Optical Microscope

Vladimir Protasenko, Katherine L. Hull, and Masaru Kuno*

University of Notre Dame, Department of Chemistry and Biochemistry and The Notre Dame Radiation Laboratory,
Received January 17, 2005. March 7, 2005.

Published online: 13 June 2005

Abstract. We demonstrate a low-cost optical microscope capable of single-molecule detection that operates in confocal, total internal reflection, epifluorescence, and brightfield transmitted light modes. The microscope detects the blinking of single CdSe/ZnS core/shell quantum dots as well as the fluorescence of single CdSe nanowires. In addition, the Brownian motion of 40-nm and 500-nm diameter dye-doped polystyrene beads suspended in water has been observed, demonstrating a wide range of applications for the microscope. Modifications to the system include the addition of a fiber-based spectrometer allowing the acquisition of fluorescence spectra from selected areas of a sample. The assembly and alignment of such a microscope not only shows different forms of modern single-molecule microscopy to both undergraduates and high school students alike but also provides a useful platform for studying microscopic processes at the single-fluorophore limit.

Key Words: Laboratories and Demonstrations; physical chemistry; chemical enginering; microscope; confocal; total internal reflection; epi-illumination; fluorescence; single molecule; quantum dots; nanowires

(*) Corresponding author. (E-mail:

Article in PDF format (1.2 MB) HTML format

Supporting Materials:

A list of the components needed to construct the microscope, modifications, assembly and alignment, optional spectrometer, CCD camera comments, and freeware comments as well as movies illustrating the experiments described are included in a Zip file as supporting materials. (47.4 MB).

Issue date: August 1, 2005

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