The first ever special form of microscope has been built by an Australian researcher, who feel it could ‘open doors’ for many new discoveries, by allowing scientists to scrutinise materials without disturbing them. I will now explain this new microscope, that is the Scanning Helium Microscope.
A Scanning Helium Microscope (SHeM) is an imaging technology based on a scanning helium ion beam. Similar to other focused ion beam techniques, it allows to combine milling and cutting of samples with their observation at sub-nanometer resolution. SHeMs have been commercially available since 2007, and a surface resolution of 0.24 nanometers has been demonstrated as well.
Paul Dastoor of the University of Newcastle, who has been working on the scanning helium microscope (SHeM) for two decades, said the new device would enable scientists to study human, animal and plant samples, as well as computer chips and pharmaceutical drugs, without damaging or changing them.
Dastoor said the development means samples would be analysed in their true state for the first time ever and every time a new microscope was developed, there had been enormous scientific advances. He led the team of researchers from the University of Newcastle, and collaborated with scientists from England’s University of Cambridge.
“We wouldn’t know anything about bacteria without the development of the optical microscope and we wouldn’t know anything about nanotechnology without the development of the electron microscope. What exactly will the new helium microscope tell us? We don’t know yet. What will it open the doors to? We don’t know yet, but it will open doors sooner,” he further added.
The scientist said that the SHeMs could be useful in major industries such as solar energy, defence, explosives and information technology. “The new device is expected to pave the way for many new discoveries because it gives new insights into structures at a microscopic level. We’re opening a window onto a new scientific world,” Dastoor said, adding that scientists would be able to see much smaller objects with a much higher resolution.
He said the ground-breaking technology may help find ways of removing carbon monoxide from exhaust gases. The SHeM could also help with the cleanup of toxic or even radioactive spills, without harming the surrounding flora or fauna.
In terms of imaging, SHIM has several advantages over the traditional scanning electron microscope (SEM). Owing to the very high source brightness, and the short De Broglie wavelength of the helium ions, which is inversely proportional to their momentum, it is possible to obtain qualitative data not achievable with conventional microscopes which use photons or electrons as the emitting source.
As the helium ion beam interacts with the sample, it does not suffer from a large excitation volume, and hence provides sharp images with a large depth of field on a wide range of materials. Compared to an SEM, the secondary electron yield is quite high, allowing for imaging with currents as low as 1 femtoamp.
The detectors provide information-rich images which offer topographic, material, crystallographic and electrical properties of the sample. In contrast to other ion beams, there is no discernible sample damage, due to relatively light mass of the helium ion. The only drawback is the cost.
“Defence experts will be interested because it could lead to the development of stealth technology and new explosives,” Dastoor said, adding that the possibilities were endless in the areas of biological sciences, pharmaceuticals and delicate materials.
“We work a lot with explosives. You don’t want to put an explosive in an energetic microscope. We really think we’re opening a window onto a new scientific world,” he said, “When you see the first image coming out on an instrument, you’ve only designed on paper. It’s certainly the time for a happy dance,” he finally ended the statement, after discovering the native cells of a genetic flower.