Module 1- Electron microscopy Flashcards
how do electron microscopes work
-use electrons instead of light
why is electron at times beneficial to light microscopy
-electrons also travel in waves but their wave length is much shorter
-shorter waves allow for much higher resolution, up to 1000x better
what are the two kinds of electron microscopes
-transmission electron microscope
-scanning electron microscope
how do transmission electron microscopes work
they shoot beams through the sample and the image is viewed by its ability to block out the electrons . like bright field microscopy
what does staining for electron microscopes use, why, and how is it done
-heavy metals
-they are more efficient at blocking electrons and are often sprayed onto the samples at an angle to create a shadowing effect to better reveal details
what are some draw backs to electron microscopes
-the sample must be viewed in a vacuum as electrons do not travel through air
-the samples need to be dehydrated, fixed and sectioned very thinly to allow electrons to transmit through to generate an image
what is an alternative way to prepare a slide for transmission electron microscopy
samples can be freeze etched which involves rapid freezing in liquid nitrogen followed by the fracturing to allow visualization of internal structures by creating a replica (ie like a mold) that can be visualized in TEM
what kind of light microscopy does scanning electron microscopy work like
it works in analogous way to dark field microscopy in how electrons are emitted but like confocal scanning microscopy in that electrons “scan” to crate an image
how does scanning electron microscopy work
-instead of detecting electrons transmitted thought the sample electrons that bounce off at an angle are detected in SEM
-then it is like confocal scanning electron microscopy in that the electron beam “scans” s focused beam, of electrons along the sample allowing the image to be generated
