Monster Machines: The STEHM Microscope

Your average atom is about 62 to 520 picometers in diameter, but since that’s a full factor smaller than the 390 to 700 nanometres human eyes can percieve, direct observation using conventional microscopes is physically impossible. But that’s where the electron beams come in. The University of Victoria, Canada, 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 picometres. It weighs over six tonnes tons, measures 4.5m tall with a 6sqm footprint and operates within the 60keV to 300keV 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 $US9.2 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 20cm of insulation and galvanised steel to minimise seismic vibrations. The outer walls are aluminium clad to block electromagnetic radiation, the inner walls are coated in acoustic dampening material and cooling panels to normalise the temperature fluctuations. What’s more the entire room in pressure controlled to minimise air flow disturbances.

When researchers insert a sample into 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 and 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 onboard electron vortex beams like subatomic chopsticks.

[Physorg, University of Victoria, University of Victoria, University of Victoria, University of Victoria, University of Victoria]