The STEHM Microscope: Finally, Nanoscientists Can See What They're Doing

Your average atom is about 62 to 520 picometers in diameter, but since that's a full factor smaller than the 390 to 700 nanometers human eye can perceive, direct observation using conventional microscopes is physically impossible. But that's where the electron beams come in. The University of Victoria has just installed the most powerful scanning electron microscope in history.


Dubbed the Scanning Transmission Electron Holography Microscope (STEHM), it's the highest resolution microscope ever constructed with a spatial resolution of just two picometers. It weighs seven tons, measures 14.7 feet tall with a 19.6 square foot footprint, operates within the 60 keV to 300 keV range, and can see roughly 20 million times better than the human eye.

Built by Hitachi High Technologies Canada using custom-crafted CEOS aberration correcting lenses, the $9.2 million STEHM required more than a year of careful installation in its purpose-built basement bunker at the University's Bob Wright Centre. To say that this is a delicate machine is a severe understatement—just look at the room that surrounds it. The basement is anchored into bedrock and entombed in eight inches of insulation and galvanized steel to minimize seismic vibrations. The outer walls are aluminum clad to block electromagnetic radiation, the inner walls are coated in acoustic dampening material and cooling panels to normalize the temperature fluctuations down to .1 degree F/hour. What's more the entire room in pressure controlled to minimize air flow disturbances.

When researchers insert a sample in the machine they have leave the room, operate it remotely, and to wait until the air currents caused by them walking around in there settle because any tiny draft will disrupt the beam. Passing clouds reportedly can affect the device's performance. So yeah, it can be a bit finicky—but it's totally worth the effort.

"The STEHM will be used by local, regional, national and international scientists and engineers for a plethora of research projects relevant to the advancement of mankind," says Rodney Herring, director of UVic's Advanced Microscopy Facility. "This enables us to see the unseen world." Herring has already set one record with the machine by resolving gold atoms at 35 picometers, beating the old mark of 49 pm.

The STEHM employs an electron beam 30 times brighter than any other SEM on the planet and two and a half times the number of lenses (most have 20, STEHM's got 50). Researchers can now not only see inside single atoms but can see what kind of atom it is, just by looking at the holography image. They'll be able to manipulate the specimens remotely as well, using the on-board electron vortex beams like subatomic chopsticks.

[Physorg - University of Victoria 1, 2, 3, 4, 5]




I always thought the problem with looking at things at a nano scale with visual or electron microscopes is that the electrons themselves will disturb the object being viewed making the returned image useless?