2 research outputs found
Energy-filtered transmission electron microscopy of biological samples on highly transparent carbon nanomembranes
Ultrathin carbon nanomembranes (CNM) comprising crosslinked biphenyl
precursors have been tested as support films for energy-filtered transmission
electron microscopy (EFTEM) of biological specimens. Due to their high
transparency CNM are ideal substrates for electron energy loss spectroscopy
(EELS) and electron spectroscopic imaging (ESI) of stained and unstained
biological samples. Virtually background-free elemental maps of tobacco mosaic
virus (TMV) and ferritin have been obtained from samples supported by ~ 1 nm
thin CNM. Furthermore, we have tested conductive carbon nanomembranes (cCNM)
comprising nanocrystalline graphene, obtained by thermal treatment of CNM, as
supports for cryoEM of ice-embedded biological samples. We imaged ice-embedded
TMV on cCNM and compared the results with images of ice-embedded TMV on
conventional carbon film (CC), thus analyzing the gain in contrast for TMV on
cCNM in a quantitative manner. In addition we have developed a method for the
preparation of vitrified specimens, suspended over the holes of a conventional
holey carbon film, while backed by ultrathin cCNM
Conversion of self-assembled monolayers into nanocrystalline graphene: Structure and electric transport
Graphene-based materials have been suggested for applications ranging from
nanoelectronics to nanobiotechnology. However, the realization of
graphene-based technologies will require large quantities of free-standing
two-dimensional (2D) carbon materials with tuneable physical and chemical
properties. Bottom-up approaches via molecular self-assembly have great
potential to fulfil this demand. Here, we report on the fabrication and
characterization of graphene made by electron-radiation induced cross-linking
of aromatic self-assembled monolayers (SAMs) and their subsequent annealing. In
this process, the SAM is converted into a nanocrystalline graphene sheet with
well defined thickness and arbitrary dimensions. Electric transport data
demonstrate that this transformation is accompanied by an insulator to metal
transition that can be utilized to control electrical properties such as
conductivity, electron mobility and ambipolar electric field effect of the
fabricated graphene sheets. The suggested route opens broad prospects towards
the engineering of free-standing 2D carbon materials with tuneable properties
on various solid substrates and on holey substrates as suspended membranes.Comment: 30 pages, 5 figure