High Resolution Transmission Electron Microscope (HRTEM) with EDAX

JEOL 3010 with a UHR polepiece operates at an accelerating voltage 300 kV. Depending upon the sample compatibility, it can work at three different accelerating voltages i.e., 300, 200 and 100 kV. This has a filament made up of LaB6. The instrument works under a vacuum in the range 10-5 to 10-6 Pa. This gives a lattice resolution of 0.14 nm and a point to point resolution of 0.12 nm

HRTEM is an instrument for high-magnification studies of nanomaterials. High resolution makes it perfect for imaging materials on the atomic scale. A main advantage of a TEM over other microscopes is that it can simultaneously give informations in real space (in the imaging mode) and reciprocal space (in the diffraction mode). Our instrument has a single tilt stage and maximum Tilt Angle of -10º to +10o in Goinometer. The instrument can operate in Bright-Field, Dark-Field, High resolution, SAED and CBED modes. We have a standard probe and a variable temperature probe (100 to 500 K). TEM is coupled with a Gatan digital camera for digital image processing. The instrument can go upto a maximum magnification of 1.5 million. It has an ACD (anti contamination device) working with the aid of liquid nitrogen, which helps the filament from contamination caused by volatile sample

Theory of operation

Basic principle of TEM is quite similar to their optical counterparts, the optical microscope. The major difference is that in TEM, a focused beam of electrons instead of light is used to “image” and achieve information about the structure and composition of the specimen. An electron source usually named as the “Gun” produces a stream of electrons which is accelerated towards the specimen using a positive electrical potential. This stream is then focused using metal apertures and magnetic lenses called “condenser lenses” into a thin, focused, monochromatic beam. Beam strikes the specimen and a part of it gets transmitted through it. This portion of the beam is again focused using a set of lenses called “objective lenses” into an image. This image is then fed down the column through the “intermediate and projector lenses”, which enlarges the image, depending upon the set magnification. A phosphor image screen is used to produce the image. The image strikes screen and light is engendered, which enables the user to see the image. The darker areas of the image represent the thicker or denser region of the sample (fewer electrons were transmitted) and the lighter areas of the image represent those areas which are thinner or less dense (more electrons were transmitted

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