July 4, 2012
Scientists Take Picture Of Atom’s Shadow
Lee Rannals for redOrbit.com - Your Universe Online
The art of microphotography just got a little smaller this week, as researchers announced they were able to snap a photo of a single atom for the first time.
"We have reached the extreme limit of microscopy; you can not see anything smaller than an atom using visible light," Professor Dave Kielpinski of Griffith University's Centre for Quantum Dynamics in Brisbane, Australia, said in a recent statement. "We wanted to investigate how few atoms are required to cast a shadow and we proved it takes just one."
The team worked for the past five years in order to try and create the tiniest of images, using a super high-resolution microscope, which makes the shadow dark enough to see.
In order to get a photo of the atom's shadow, the researchers had to ensure the atom would hold still long enough. The team isolated the atom within a chamber, and held it in free space by electrical forces to keep it from moving around.
The scientists trapped single atomic ions of the element ytterbium, and exposed them to a specific frequency of light.
Under this frequency of light, the atom's shadow was cast onto a detector, and a digital camera was able to capture an image of it.
"By using the ultra hi-res microscope we were able to concentrate the image down to a smaller area than has been achieved before, creating a darker image which is easier to see", Professor Kielpinski said.
The researchers had to use plenty of precision in order to ensure the delicate process would work.
"If we change the frequency of the light we shine on the atom by just one part in a billion, the image can no longer be seen," Professor Kielpinski said.
Dr Erik Streed, another researcher on the project, said the implications of these findings are far reaching.
"Such experiments help confirm our understanding of atomic physics and may be useful for quantum computing," Dr Streed said in a statement. "Because we are able to predict how dark a single atom should be, as in how much light it should absorb in forming a shadow, we can measure if the microscope is achieving the maximum contrast allowed by physics."
He said this research is important if someone wants to look at very small and fragile biological samples, like DNA strands where exposure to too much UV light or x-rays will harm the material.
"We can now predict how much light is needed to observe processes within cells, under optimum microscopy conditions, without crossing the threshold and destroying them," Streed said. "In the end, a little bit of light just might be enough to get the job done."
Image 2 Credit (below): Griffith University