April 22, 2015

Electron Microscopy Lab

The LVEM5 is truly a 4-in-1 electron microscope. Not only is it a Transmission Electron Microscope (TEM), but it can be configured with up to two different scanning modes for use as a Scanning Election Microscope (SEM) and a Scanning Transmission Electron Microscope (STEM). There is also the ability to perform Electron diffraction (ED)

The Low Voltage Electron Microscope LVEM is designed to excel across a broad range of applications such as biology, medical diagnosis, and materials science. Using unstained samples you are able to observe the objects close to their native state with ultra high contrast and nanometer resolutions.

TEM Transmission Electron Microscope

Transmission electron microscopes (TEM) working at accelerating voltage 100 kV require to cut the majority of biological specimens in ultrathin sections with the thickness in the range 50-80 nm. The resulting image from TEM represents a superimposition of all structures into the section occurring in an observed area. The low voltage transmission electron microscope (LVTEM) works at accelerating voltage 5 kV and that is why it needs much more thinner sections from specimens with the thickness only 15-20 nm. The advantage of using so low accelerating voltage is the substantial reduction of the superimposition in addition to the contrast enhancement.

SEM Scanning Electron Microscope

In Scanning Electron Microscope (SEM) mode, the beam never transmits through the sample. Instead, the beam is scanned back and forth over the sample. Electrons that rebound off the sample are collected by a special back scattered electron detector (BSE) and an image of the surface structure and compositional information is created. The BSE detector is broken down into quadrants, offering multiple view angles of the object. With SEM imaging most any sample can be observed, regardless of staining or section thickness.

Practically any solid sample can be observed in SEM mode, with minimal prior preparation. While coating is often required for SEM imaging of non-conductive materials, the low accelerating voltage of the LVEM5 allows observation of many non-conductive samples in their native state, without coating. Typical samples for SEM observation are sections or fracture surfaces of bulk specimens, as well as nanoparticles or filaments distributed on a substrate.

Specifications

The LVEM is a compact bench top instrument that combines high-resolution imaging with the small footprint of an optical microscope. It consists of four separate parts; the microscope, the electronics unit, the vacuum system, and the PC.

The microscope consists of two parts; the first one is a miniature 5 kV transmission electron microscope with the maximum magnification 500 times equipped by emitter source of Schottky type, permanent magnetic lenses for image formation, and electrostatic lenses to control magnification. The invisible electron images are converted to the light ones by means of a single crystal YAG fluorescent screen. The second part of the device is a conventional optical microscope with the maximum magnification 400 times equipped by CCD camera for image recording. The resolution power of LVTEM is 2 nm.

Contact Information

Dr. Hegaly Mendoza

hegaly.mendoza@unab.cl
+ 56-2-2770 3525
Center for Bioinformatics and Integrative Biology
Universidad Andrés Bello
Av Republica 239, Santiago, Chile. Postal code 8370146