The microscope itself is a sleek, imposing, and strangely elegant piece of machinery. For a layman unfamiliar with the trappings of a hard science research lab, it's hard to tell exactly what it is on first glance. It dominates the tiny, informal room like a science fiction supercomputer, the findings of its extraordinary eye displayed by a pair of computers stationed nearby.
I watched it for some time. On the screen floated a grainy grayscale image awash with curiously uniform static. Silver dots and lines formed complex patterns. Our guide pointed to the display and said "We're looking at a highly magnified piece of silver. The dots you see are individual silver atoms."
Atoms. I'd never seen an actual image of them before-- not one displayed live, anyway. They trembled as the guide spoke, the sound waves from his voice crashing against the highly delicate machine.
It was a pretty cool experience, but it made me realise that, although I knew it was physically possible to see atoms, I didn't have the slightest idea how. What exactly is an electron microscope, and how can it let us see something so small that even bacteria stand as giants before it?
A Finer Lens
A conventional or "light" microscope as you might see in a high school biology lab works, to put it very simply, by stacking two convex lenses atop one another. These lenses "bend" the light shining up from the microscope's stage, thus magnifying the image and allowing the human eye to perceive materials and organisms far smaller than it otherwise could.
However, light microscopes have their limitations, the most notable being the wavelength of visible light. As light waves within the visible spectrum oscillate every 400-700 nanometres, anything smaller than this cannot be properly seen through a light microscope. Hardly a problem when dealing with larger cells, but on a molecular level, a max resolution of 400 nanometres leaves a lot of stuff out of the equation (an atom's size, including its electron orbit, ranges from 0.1 to 0.5 nanometres).
For centuries, this limitation made the atom a purely theoretical construct, something that had long been postulated about-- permutations of atomic theory, albeit deeply flawed ones, extend as far back as 400 BCE-- but never properly seen. It wasn't until the beginning of the 20th century, when the cathode ray became marketable, that the idea of using something with a wavelength far smaller than light to produce images became practical. That something was electrons.
Put simply, an electron microscope shoots a beam of electrons through a specimen, which can be anything from a prepared metal to a piece of organic matter. By meticulously observing the reactions of these electrons, the microscope constructs a highly accurate image of the specimen at a maximum resolution that far exceeds what a light microscope is capable of.
Sweat the Small Stuff
Obviously, the electron microscope exponentially increased our capacity to understand-- and tinker with-- the basic building blocks of matter. Carleton's new purchase can reach resolutions of 0.144 nm, allowing it to see not just atoms, but atomic bonds.
It's the most powerful microscope in Ottawa at the moment, and its uses are not wholly academic. Environment Canada intends to use the microscope for a variety of important projects, and the microscope will be made available to other clients as well.
So if you feel like taking a closer look-- a much, much, much closer look-- at that mole on your arm, give them a shout. I'm sure they'll hook you up (if the price is right).