Bare Single-Hole Copper & Molybdenum TEM Grids
Ultrathin Carbon Film
Ultrathin carbon film is a type of support film in which a very thin
carbon layer is deposited over a microgrid support film. The typical
thickness of this ultrathin carbon layer is 3–5 nm.
The purpose of the ultrathin carbon layer is to cover the micropores.
It is mainly intended for well-dispersed nanomaterials, especially
specimens smaller than 10 nm.
When a microgrid is used alone, very small particles may pass through
the micropores. Particles positioned near the edges of the holes may
also be more difficult to observe because the thicker support area can
affect imaging.
Ultrathin carbon films can therefore provide improved observation
results for these specimens. Available grid materials include copper,
nickel, molybdenum and gold.
Microgrid Carbon Support Film
Microgrid carbon film is a type of support film in which micropores
are intentionally formed during preparation. It is therefore also
referred to as a microgrid support film.
The support film is carbon coated and generally has a film thickness
of 15–20 nm. Its main purpose is to allow specimens to be supported
near the edges of the micropores so that portions of the sample can
be observed without an underlying film.
Film-free observation helps improve image contrast. Microgrid support
films are commonly used for tubular, rod-shaped and nanoparticle
aggregate specimens and are particularly useful for high-resolution
imaging.
Carbon film thickness can be customized according to the application.
For specimen particles smaller than 10 nm, ultrathin carbon film
is recommended.
Carbon Support Film
Carbon support film is a specimen carrier used for transmission
electron microscopy (TEM). It consists of a carbon layer deposited
over an organic Formvar film.
During TEM observation, the grid support film may accumulate
electrical charge under electron-beam irradiation. This can result
in specimen charging, drift, movement or support-film breakage.
Carbon coating improves the electrical conductivity of the support
film and helps provide better observation results.
This carbon-coated grid support film is commonly referred to as
a carbon support film and generally has a film thickness of 7–10 nm.
The support film is mainly composed of an organic layer with a thin
carbon coating, so background interference is generally low.
Samples are commonly dispersed in water or ethanol, and the support
film is generally resistant to corrosion.
Double-Grid Carbon Support Film
Double-grid carbon support film is designed specifically for magnetic
specimens. Magnetic samples may contaminate the electron microscope,
so carbon films are mounted on both grids and the specimen is enclosed
between them for protection.
The double-grid carbon support film is simple to use and is handled
similarly to a conventional single-grid carbon support film. The
dispersed specimen is placed on one grid and the second grid is then
attached over it.
This method simplifies conventional preparation procedures for magnetic
specimens and significantly reduces specimen preparation time.
Magnetic powder samples can be prepared either by resin embedding
with ultrathin sectioning or by using a double-grid carbon support film.
Quantifoil Holey Carbon Film
Quantifoil is a perforated support film with precisely arranged holes
of different sizes and shapes. Compared with conventional holey carbon
films, it offers advantages for transmission electron microscopy (TEM)
grids and low-energy electron point-source microscopy (LEEPS).
The fixed geometric arrangement of Quantifoil holes facilitates
automated operation in TEM, which is generally not possible with
conventional carbon films.
Quantifoil carbon support films have a large open-hole area and are
commonly used to reduce specimen thickness and minimize artifacts
caused by the support film.
The perforated carbon film can support ultrathin films or can be used
directly as a carrier for larger specimens such as micron-scale powders.
This is useful for electron diffraction (ED), electron energy-loss
spectroscopy (EELS), EELS imaging and dark-field imaging.
It can also be used for nanomaterial characterization, including
studies of biological macromolecular complexes freely suspended
over the holes.
Surface properties of Quantifoil grids, especially wettability,
can be adjusted according to user requirements. Like other carbon
films, untreated Quantifoil films gradually lose hydrophilicity
over time, while newly prepared carbon films generally have
better hydrophilicity.
Round-Hole Quantifoil Carbon Film
Round-hole Quantifoil carbon film is particularly suitable for
cryogenic transmission electron microscopy (Cryo-TEM), because
circular holes help form ice layers with more uniform thickness.
Hole spacing should be selected according to the required magnification
and whether the support-film pattern will appear in the final image.
If the film is included in the final image, image-quality evaluation
is easier because the film provides more acceptable isolated ice areas.
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