MAG*I*CAL Calibration Specimen for Transmission Electron Microscopes
Developed over a period of years at one of Canada's premier research institutions, this unique calibration sample for use in all transmission electron microscopes (TEMs) can be used to perform all of the three major calibrations for a TEM:
1) Magnification at all magnification ranges
2) Camera constant
3) Image-diffraction pattern rotation calibrations
With this newly developed single crystal material, a single sample can replace up to five other calibration samples. While the sample itself was developed by materials scientists using materials science techniques, life scientists doing TEM will find the use of this calibration aid to be equally useful. We also believe the Mag*I*cal TEM Calibration Sample will come about as close as one could get to having a"certified standard". A Certificate of Analysis accompanies each Mag*I*Cal sample that is shipped to a customer. And we are now sending with each Mag*I*Cal a Certificate of Traceability.
What the sample looks like physically
The arrows indicate the four possible regions of interest on the sample where the calibration marks may be found. Note that this cross-sectional sample consists of two pieces of silicon wafer epoxied face-to-face, with additional silicon added as backing material to form a 3 mm disk. To find the areas of interest at low magnification, look for the epoxy line on either side (between the arrows) in figure 1.
Thickness of the sample:
The MAG*I*CAL is an ion milled cross section, so the thickness varies from nominally zero thickness at the perforation (in reality, ~3 nm) up to the full sample thickness of 50 microns. The electron transparent area (near the central perforation) increases in thickness at an angle of ~1 degree up to well beyond the electron transparent region (>1 micron total thickness).
Description of the Mag*I*Cal Calibration Sample
The sample itself is an ion milled cross-section of a single crystal of silicon. In this single crystal are a series of atomically flat layers of Si and SiGe. They have been produced to electronic device quality by molecular beam epitaxy (MBE). The thickness and spacing of these layers are very accurately known, since they have been directly referenced to the (111) crystal lattice spacings of silicon, which are readily visible right on the sample.
The layer spacings are designed so that the sample can be used to calibrate the entire magnification range in a TEM, from about 1000X up to 1,000,000X. No other sample in the world can cover this broad of a range of magnifications! Since the sample itself is a single crystal, it can also be used to perform the camera constant calibration and also the image-diffraction pattern rotation calibration.
Thickness of the Mag*I*Cal Calibration Sample
The thickness of the sample varies from about 10 nm at the edge of the perforation (the thinnest regions closest to the perforation contain too much amorphized material at both surfaces to be useful) to about 50 µm at the very edge of the grid. The useful area for TEM purposes depends on the TEM accelerating voltage, but generally thicknesses of up to 1 µm are usable in all modern TEMs. The "thickening" rate varies with each sample, but the angle of the sample material near the perforation is about 10° or less (for example, for 10°, the sample would be about 1 µm thick at a position about 5 µm in from the perforation).
If after reading a more extensive description of the product, and you still have questions, let us know and we will try our best to answer them. If one is using an x-ray spot, and if the spot size is about 5 µm diameter, and the spot was positioned in the thinnest region of the sample, the average thickness will be 2.5 µm, but would vary across the sample from 0 to 5 µm thickness.
And of course, the sample comes with simple, easy to follow instructions for all calibrations.
This product is fragile!
The Mag*I*Cal TEM Calibration Sample is fragile. It is brittle. And it is easily broken. We don't want a current or prospective customer to underestimate its fragility. However, this should not deter the careful TEM user from making use of this one-of-a-kind calibration sample and we do have many customers who have been using successfully and without incident for years. Breakage of the sample is not covered on our standard warranty. In order to reduce the chances of damage to the Mag*I*Cal sample, we recommend that for storage, it be returned to its membrane box shipping container. We recommend that the Mag*I*Cal sample be allowed to drop gently onto the membrane of the membrane box since if you are still holding the sample with tweezers, when it touches the membrane, it could be slightly bent and summarily broken. If you accidentally break the membrane, rather than putting your Mag*I*Cal sample at risk, we would recommend purchasing a replacement membrane box at once.