Holey carbon film for electron microscopy or low-energy electron point source microscopy.
- Offered with circular and square, orthogonal arranged holes
- Hole sizes from 0.6, 1, 1.2, 2, 3, 3.5, 5, 6, 10 and 17.5 µm
- 200, 300, and 400 mesh copper and nickel grids
- Carbon film is about 10 to 12 nm thick
The surface properties of QUANTIFOIL® holey carbon support film, especially the wetting properties, may have to be adapted according to one's particular requirements. Untreated aging QUANTIFOIL® tends to be hydrophobic. Hydrophillicity of the foil can be achieved by glow discharging in residual air or by metal coating.
QUANTIFOIL® in low-energy electron point source (LEEPS) microscopy. Quantifoil® with a regular pattern is required in order to be able to distinguish an object, which is spanned over a hole. An object cannot be discriminated from the support in the case of conventional holey support film. (H.W. Fink & C. Schonenberger, University of Basel, used QUANTIFOIL® for the measurement of electrical current through DNA molecules)
The foil is ~12 nm thick and mounted on either copper, nickel or gold grids with either square or round holes of different sizes. Holey films with 2 µm round holes are used at magnifications between 30000× and 40000×.
QUANTIFOIL® with circular holes is mainly used in cryo-EM. The roundness of the holes is advantageous with respect to the formation of an ice layer of constant thickness. The hole size that is chosen depends on the magnification used, and on whether or not one wishes to include support film in the image. The latter makes assessment of the image quality easier, because the power spectrum of a foil is stronger than that of unsupported ice. The QUANTIFOIL® types with small holes (1.2 µm) were designed for magnifications around and higher 50000×. At magnifications between 30000× and 40000× we recommend the QUANTIFOIL® types with 2 µm holes. Larger holes (3.5 µm, 5 µm) are suitable at magnification around 20000×.
QUANTIFOIL® R 3.5/1 may be preferred over foils with smaller holes if the carbon film should be outside the frame of the image. This option can be desirable in the case of extended objects, such as filamentous objects, for example.
QUANTIFOIL® R 1/4 may be preferred over R 1.2/1.3, when an increased tolerance with respect to the position of beam, and a larger beam diameter are desired, such as in the case of automated image acquisition.
QUANTIFOIL® R 0.6/1 Hole size is 0.5 µm. Space between holes is 1 µm. Center to center is 1.6 µm (hole size may be as large as 1 µm).
QUANTIFOIL® R 5/20 Hole size is 5 µm. Space between holes is 20 µm. Center to center is 25 µm.
QUANTIFOIL® R 2/4 may be preferred over R 2/2, when an increased tolerance with respect to the position of beam, and a larger beam diameter are desired, such as in the case of automated image acquisition.
QUANTIFOIL® R 2/2 Holey films with 2 µm circular holes are used at magnifications between 30000× and 40000×.
QUANTIFOIL® R 2/1 has more open area than R 2/2. It is used when focusing is carried out on the edge of a hole burnt in the ice in a neighboring hole instead of on the foil adjacent to the hole.
QUANTIFOIL® R 1.2/1.3 A foil with ~1.2 µm circular holes and a spacing of ~2.5 µm between the holes. This type is used at magnifications around 50000×.
QUANTIFOIL® with square holes and relatively narrow bars can be used in electron microscopy to support a thin carbon film, which by itself is too fragile to span a grid square. The QUANTIFOIL® types with square holes constitute an optimum between a maximum of open area on the one hand, and mechanical stability on the other hand.
QUANTIFOIL® S 7/2 constitutes an optimum between a maximum of open area on the one hand, and mechanical stability on the other hand.
QUANTIFOIL® Multi A is a holey film, in which a pattern of various hole sizes, shapes and arrangements is repeated. In addition to circular holes, the pattern includes oval-shaped ones which appear round at high tilt angles (~70°). The circular holes have diameters of 1 µm, 1.4 µm, and 2 µm. The elliptical holes measure 1×4 µm and 2×8 µm (along the shortest and longest axes, respectively).
QUANTIFOIL® with Hexagonal Geometry is meant for slot grids. It was especially designed for supporting serial thin sections. It offers an optimum between mechanical stability on the one hand and background-free area on the other hand. The foil is thin enough to allow those parts of the sections that lie on the bars to be interpreted. In this way, the information in the sections can be interpreted to the maximum. QUANTIFOIL® Hex 15 A foil with hole size of 26 µm (diameter of inscribed circle) and a repeating distance of 41 µm, the side length of the holes and the bar width are 15 µm.
Ordering information: QUANTIFOIL® is generally delivered as a carbon foil; it can be reinforced with plastic film. The standard thickness for the carbon foil is 12 nm; other thicknesses between 10 and 25 nm can be made upon request.
Packaging: The grids are packed with their coated side toward the center of the grid box.
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