Visualizing Graphene Based Sheets by Fluorescence Quenching Microscopy

Abstract

Graphene based sheets have stimulated great interest due to their superior mechanical, electrical, and thermal properties. A general visualization method that allows quick observation of these single atomic layers would be highly desirable as it can greatly facilitate sample evaluation and manipulation, and provide immediate feedback to improve synthesis and processing strategies. Here we report that graphene based sheets can be made highly visible under a fluorescence microscope by quenching the emission from a dye coating, which can be conveniently removed afterward by rinsing without disrupting the sheets. Current imaging techniques for graphene based sheets rely on the use of special substrates. In contrast, the fluorescence quenching mechanism is no longer limited by the type of substrate. Graphene, reduced graphene oxide, or even graphene oxide sheets deposited on arbitrary substrates can now be readily visualized with good contrast for layer counting. Direct observation of suspended sheets in solution was also demonstrated. The fluorescence quenching microscopy offers unprecedented imaging flexibility and could become a general tool for characterizing graphene based materials.

Interphases in Graphene Polymer‐based Nanocomposites: Achievements and Challenges

“…The empty states in the conduction band above the Fermi level in graphene could act as acceptor for the photoexcited electron of the dye, whereas the fi lled valence band of graphene could act as a donor for electrons able to refi ll the remaining holes in the ground state of the dye. This ability of graphene to quench fl uorescence emission has been successfully applied by Kim and co-workers, [ 85 ] to obtain images of graphene layers with a simple fl uorescence microscope.…”

Comparison of Graphene Oxide and Reduced Graphene Oxide for DNA Adsorption and Sensing

“…[34][35][36] Interestingly, the number of optical sensors using 4 rGO is quite limited, [36][37][38][39] despite that rGO is a better fluorescence quencher. 40 From the surface science perspective, rGO might adsorb DNA more tightly since it has a lower surface charge density (thus less electrostatic repulsion with negatively charged DNA). In addition, rGO has more aromatic regions for - stacking with DNA bases.…”

Fluorescence quenching in graphene: A fundamental ruler and evidence for transverse plasmons

“…4 The large intrinsic carrier mobilities and doping tunability have led to a number of proposals for optoelectronic applications, 1,[5][6][7] where the engineering of long-lived graphene plasmons could play a major role. [8][9][10] Graphene (and its oxide) exhibits excellent quenching of nearby fluorescent materials, [11][12][13][14] a property shared with carbon nanotubes. 15,16 This technique has allowed spectacular contrast images, enabling far easier optical identification 12 (and prospects for device manipulation 17 ) of graphene's flakes.…”

“…[8][9][10] Graphene (and its oxide) exhibits excellent quenching of nearby fluorescent materials, [11][12][13][14] a property shared with carbon nanotubes. 15,16 This technique has allowed spectacular contrast images, enabling far easier optical identification 12 (and prospects for device manipulation 17 ) of graphene's flakes. Given the mature nature of fluorescent microscopy, particularly in the biological sciences, their combination with increasingly available and versatile graphene nanostructures could open interesting research directions.…”