Anumol Ashok is a researcher at the Department of Materials and Environmental Chemistry (MMK). She spends most of her time working with the transmission electron microscopes at the Electron Microscopy Center (EMC) of the department and has been working at Stockholm University for about two years.

“We train researchers, and after training they can use the microscopes themselves. We also offer a service of operating a microscope for researchers that only use it for a few sessions. It can either be as a collaboration where we are involved in planning the research, or as a service where we only help them in using the microscope”

The microscopes are being used as normal even during the pandemic. “The researchers come here only when they need to use the instruments or the labs, and then do everything else from home. So it’s not crowded at the department.”

At MMK there are three TEMs – Transmission electron microscopes. The most advanced one, an aberration corrected TEM-Thermo Fisher Scientific™ Themis Z, is still referred to as “the new TEM” even though it’s been there for more than two years. It’s however still one of the most advanced microscopes in Sweden and one of the best electron microscopes available in the world.

“It’s one of the university’s and MMK’s largest investments. It’s always booked daytime during working days, and sometimes in weekends and evenings as well,” says Anumol Ashok.

With the new TEM it’s possible to see single atoms and identify the elements using spectroscopy. In the photo on the screen there’s gold particles with atoms seen as bright dots.
“This is a standard sample we use for alignment and calibration. We start each day with this one,” says Anumol Ashok.

The new TEM is controlled by two panels and software in the operator room. For the department’s other two TEMs the users can sit next to the microscope and operate it, but this advanced instrument needs an environment completely free of vibrations to achieve the best resolution.

“Just by talking we would make too much vibrations to get a clear image of the sample”, says Anumol Ashok.

The joystick is used to move the sample, and turning the knobs changes the magnification.

Placing the sample in the holder requires precision. The sample can be up to 3 mm wide, but it’s the thickness that is important. If it’s too thick the electrons just bounce back and there will be no image. How thin the sample needs to be depended on the density of the material. For heavy metals, like gold, the thickness can be up to a few tens of nanometers. In comparison, a strand of hair is about 80 000 nanometers thick

Sharp and delicate instruments are needed to handle the small samples.

Placing the sample holder in the microscope. The sample is now ready to be beamed with electrons to reveal the structures invisible to the eye or to a regular light microscope.

Just a regular floor? No, the floor on which the microscope stands is isolated from all vibrations. When “the new TEM” was installed it required extensive renovations of the Arrhenius Laboratory building to shield the microscope from floor vibrations, acoustic noise and electromagnetic interferences.