  Here a new microscopic method is proposed to image and characterize very thin
samples like few-layer materials, organic molecules, and nanostructures with
nanometer or sub-nanometer resolution using electron beams of energies lower
than 20 eV. The microscopic technique achieves high resolution through the
proximity (or near-field) effect, as in scanning tunneling microscopy (STM),
while it also allows detection of transmitted electrons for imaging and
spectroscopy, as in scanning transmission electron microscopy (STEM). This
proximity transmission electron microscopy (PSTEM) does not require any lens to
focus the electron beam. It also allows detailed characterization of the
interaction of low-energy electron with materials. PSTEM can operate in a way
very similar to scanning tunneling microscopy, which provides high-resolution
imaging of geometric and electronic structures of the sample surface. In
addition, it allows imaging and characterization of the interior structures of
the sample based on the detected transmission electron signals. PSTEM comprises
a family of spectroscopies that address the transport and scattering of
low-energy electrons in materials. Thus rich information can be extracted from
the measurements. PSTEM offers a fundamentally new and powerful way to
investigate thin materials. New analysis methods of thin materials and new
physics may be uncovered by this method.
