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Published on: July 24, 2015
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Strong repulsive Lifshitz-van der Waals forces on suspended graphene
Gianluca Vagli1, Tian Tian1,2, Franzisca Naef1
1Institute for Chemical and Bioengineering, ETH Zürich, Zürich, Switzerland.
Nature Communications
|August 19, 2025
Summary
Researchers discovered a repulsive Lifshitz-van der Waals force from suspended graphene surfaces. This finding, measured using atomic force microscopy, could enable new technologies like quantum levitation.
Area of Science:
- Surface science
- Materials science
- Nanotechnology
Background:
- Understanding surface forces of two-dimensional (2D) materials is crucial for nanoscale molecular dynamics.
- Intrinsic surface properties of 2D materials, especially suspended ones, are not well understood.
- Existing knowledge primarily focuses on substrate-supported 2D monolayers.
Purpose of the Study:
- To investigate the intrinsic surface forces of suspended graphene.
- To measure and characterize the repulsive forces exerted by suspended graphene.
- To develop a theoretical model accounting for graphene's flexibility.
Main Methods:
- Utilized atomic force microscopy (AFM) for direct force measurements.
- Employed a theoretical model incorporating graphene's flexibility.
- Measured forces between a gold-coated AFM tip and suspended graphene sheets.
Main Results:
- Directly measured repulsive Lifshitz-van der Waals forces from suspended graphene.
- Detected an average repulsive force of up to 1.4 kN/m² at 8.8 nm separation.
- Observed forces significantly larger (over two orders of magnitude) than predicted long-range Casimir-Lifshitz repulsion in fluids.
Conclusions:
- Suspended 2D materials generate significant repulsive forces on nearby neutral objects.
- These forces can lead to reduced wettability of surfaces.
- Potential applications include molecular actuation and quantum levitation.
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