BUFFALO, N.Y. — It’s not X-ray vision, but you could
call it infrared vision.
A University at Buffalo-led research team has developed a
technique for “seeing through” a stack of graphene
sheets to identify and describe the electronic properties of each
individual sheet — even when the sheets are covering each
The method involves shooting a beam of infrared light at the
stack, and measuring how the light wave's direction of oscillation
changes as it bounces off the layers within.
To explain further: When a magnetic field is applied and
increased, different types of graphene alter the direction of
oscillation, or polarization, in different ways. A graphene layer
stacked neatly on top of another will have a different effect on
polarization than a graphene layer that is messily stacked.
“By measuring the polarization of reflected light from
graphene in a magnetic field and using new analysis techniques, we
have developed an ultrasensitive fingerprinting tool that is
capable of identifying and characterizing different graphene
multilayers,” said John Cerne, PhD, UB associate professor of
physics, who led the project.
The technique allows the researchers to examine dozens of
individual layers within a stack.
Graphene, a nanomaterial that consists of a single layer of
carbon atoms, has generated huge interest due to its remarkable
fundamental properties and technological applications. It’s
lightweight but also one of the world’s strongest materials.
So incredible are its characteristics that it garnered a Nobel
Prize in Physics in 2010 for two scientists who pioneered its
Cerne’s new research looks at graphene’s electronic
properties, which change as sheets of the material are stacked on
top of one another. The findings appeared
Nov. 5 in Scientific Reports, an online, open-access journal
produced by the publishers of Nature.
Cerne’s collaborators included colleagues from UB and the
U.S. Naval Research Laboratory.
So, why don’t all graphene layers affect the polarization
of light the same way?
Cerne says the answer lies in the fact that different layers
absorb and emit light in different ways.
The study showed that absorption and emission patterns change
when a magnetic field is applied, which means that scientists can
turn the polarization of light on and off either by applying a
magnetic field to graphene layers or, more quickly, by applying a
voltage that sends electrons flowing through the graphene.
“Applying a voltage would allow for fast modulation, which
opens up the possibility for new optical devices using graphene for
communications, imaging and signal processing,” said first
author Chase T. Ellis, a former graduate research assistant at UB
and current postdoctoral fellow at the Naval Research