Graphene liquid cell allows high-resolution atomic imagingFri, 13 Apr 2012
Scientists can now observe processes occurring in liquid media at a scale less than a nanometer (billionth of a meter).
Advanced Institute of Science and Technology (KAIST) scientists
confined an ultra-thin liquid film between layers of graphene, for
real-time and in-situ imaging of nanoscale processes in fluids, with
atomic-level resolution, by a transmission electron microscope (TEM).
graphene liquid cell (GLC) is composed of two sheets of graphene
sandwiched to create a sealed chamber, where a platinum growth solution
is encapsulated in the form of a thin slice. Each graphene layer has a
thickness of one carbon atom, the thinnest membrane that has ever been
used to fabricate a liquid cell required for TEM.
team was able to observe the growth and dynamics of platinum
nanocrystals in solution as they coalesced into a larger size, while the
graphene membrane with the encapsulated liquid remained intact.
transmission electron microscope (TEM), first introduced in the 1930s,
produces images at a significantly higher resolution than light
microscopes, allowing users to examine the smallest level of physical,
chemical, and biological phenomena. Observations by TEM with atomic
resolution, however, have been limited to solid and/or frozen samples,
and thus it has previously been impossible to study the real time fluid
dynamics of liquid phases.
TEM imaging is performed in a high
vacuum chamber in which a thin slice of the imaged sample is situated,
and an electron beam passes through the slice to create an image. In
this process, a liquid medium, unlike solid or frozen samples,
evaporates, making it difficult to observe under TEM.