what is the highest magnification of TEM (transmission electron microscope?

Answer 1

In the past, light microscopes have been used mostly for imaging due to their relative ease of use. However, the maximum resolution that one can image is determined by the wavelength of the photons that are being used to probe the sample. In the early days of microscopy nothing smaller than the wavelength being used could be resolved, whereas nowadays the law of RESOLFT sets the limit for optical microscopes employing such concepts (see microscope). Visible light has wavelengths of 400–700 nanometers; larger than many objects of interest. Ultraviolet could be used, but soon runs into problems of absorption. Even shorter wavelengths, such as X-rays, exhibit a lack of interaction: both in focusing (nothing interacts strongly enough to act as a lens) and actually interacting with the sample

Modern research TEMs may include aberration correctors, to reduce the amount of distortion in the image, allowing information on features on the scale of 0.1 nm to be obtained (resolutions down to 0.08 nm have been demonstrated, so far). Monochromators may also be used which reduce the energy spread of the incident electron beam to less than 0.15 eV. Major TEM makers include JEOL, Hitachi High-technologies, FEI Co. and Carl Zeiss.

In the most powerful diffraction contrast TEM instruments, crystal structure can also be investigated by High Resolution Transmission Electron Microscopy (HRTEM), also known as phase contrast imaging as the images are formed due to differences in phase of electron waves scattered through a thin specimen.

Resolution of the HRTEM is limited by spherical and chromatic aberration, but a new generation of aberration correctors has been able to overcome spherical aberration. Software correction of spherical aberration has allowed the production of images with sufficient resolution to show carbon atoms in diamond separated by only 0.89 ångströms (89 pm, one ångström is 0.0000000001 of a meter or 100 picometers) and atoms in silicon at 0.78 ångströms (78 pm) at magnifications of 50 million times. Improved resolution has also allowed the imaging of lighter atoms that scatter electrons less efficiently — lithium atoms have been imaged in lithium battery materials. The ability to determine the positions of atoms within materials has made the HRTEM an indispensable tool for nanotechnology research and development in many fields, including heterogeneous catalysis and the development of semiconductor devices for electronics and photonics.

Answer 2

yeah alex is right . and also SEM can show you a deeper image .