Grids / grilles 300 mesh R 6/6.5- 50/pk- Circular Holes – Quantifoil

Description

QUANTIFOIL® – Holey Carbon Films

QUANTIFOIL® is a perforated support foil with pre-defined hole size, shape and arrangement. It has advantages in electron microscopy (EM) or low-energy electron point source (LEEPS) microscopy when compared with conventional holey film.

QUANTIFOIL® is offered with circular and square, orthogonal arranged holes. Films with different hole sizes and bar widths are available. Carbon is the standard material that makes the foil.

QUANTIFOIL® is a superior quality of holey carbon film, which facilitates the use of automation in TEM. (e.g. The National Resource for Automated Molecular Microscopy, at the Scripps Research Institute, has developed a system, called Leginon, for automatically acquiring images from a transmission electron microscope).

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 ~12nm thick and mounted on either copper, nickel or gold grids with either square or round holes of different sizes.

Holey films with 2µ round holes are used at magnifications between 30,000x and 40,000x.

QUANTIFOIL® with Circular Holes

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 (e.g. 1.2µm) were designed for magnifications around and higher 50,000x. At magnifications between 30,000x and 40,000x we recommend the QUANTIFOIL® types with 2µm holes. Larger holes (e.g. 3.5µm, 5µm) are suitable at magnification around 20,000x.

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 0.5µ. Space between holes is 1µ. Center to center is 1.6µ (hole size may be as large as 1µ). QUANTIFOIL® R 5/20 Hole size is 5µ. Space between holes is 20µ. Center to center is 25µ. 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 2µm circular holes are used at magnifications between 30,000x and 40,000x.

QUANTIFOIL® R 2/1 has more open area than R 2/2. It is used whenfocusing 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 ~1.2µm circular holes and a spacing of ~2.5µm between the holes. This type is used at magnifications around 50,000x.

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