Nav: Home

Laser takes pictures of electrons in crystals

July 01, 2020

The researchers used powerful laser flashes to irradiate thin, films of crystalline materials. These laser pulses drove crystal electrons into a fast wiggling motion. As the electrons bounced off with the surrounding electrons, they emitted radiation in the extreme ultraviolet part of the spectrum. By analyzing the properties of this radiation, the researchers composed pictures that illustrate how the electron cloud is distributed among atoms in the crystal lattice of solids with a resolution of a few tens of picometers which is a billionth of a millimeter. The experiments pave the way towards developing a new class of laser-based microscopes that could allow physicists, chemists, and material scientists to peer into the details of the microcosm with unprecedented resolution and to deeply understand and eventually control the chemical and the electronic properties of materials. (Nature, July 1 2020)

For decades scientists have used flashes of laser light to understand the inner workings of the microcosm. Such lasers flashes can now track ultrafast microscopic processes inside solids. Still they cannot spatially resolve electrons, that is, to see how electrons occupy the minute space among atoms in crystals, and how they form the chemical bonds that hold atoms together. The reason is long known. It was discovered by Abbe more than a century back. Visible light can only discern objects commensurable in size to its wavelength which is approximately few hundreds of nanometers. But to see electrons, the microscopes have to increase their magnification power by a few thousand times.

To overcome this limitation, Goulielmakis and coworkers took a different path. They developed a microscope that works with powerful laser pulses. They dubbed their device as the Light Picoscope. "A powerful laser pulse can force electrons inside crystalline materials to become the photographers of the space around them." When the laser pulse penetrates inside the crystal, it can grab an electron and drive it into a fast- wiggling motion. "As the electron moves, it feels the space around it, just like your car feels the uneven surface of a bumpy road," said Harshit Lakhotia, a researcher of the group. When the laser-driven electrons cross a bump made by other electrons or atoms, it decelerates and emits radiation at a frequency much higher than that of the lasers. "By recording and analyzing the properties of this radiation, we can deduce the shape of these minute bumps, and we can draw pictures that show where the electron density in the crystal is high or low," said Hee-Yong Kim, a doctorate researcher in Extreme Photonics Labs. "Laser Picoscopy combines the capability of peering into the bulk of materials, like x-rays, and that of probing valence electrons. The latter is possible by scanning tunneling microscopes but only on surfaces."

"With a microscope capable of probing, the valence electron density we may soon be able to benchmark the performance of computational solid-state physics tools," said Sheng Meng, from the Institute of Physics, Beijing, and a theoretical solid-state physicist in the research team. "We can optimize modern, state-of-the-art models to predict the properties of materials with ever finer detail. This is an exciting aspect that laser picoscopy brings in," he continues.

Now the researchers are working on developing the technique further. They plan to probe electrons in three dimensions and further benchmark the method with a broad range of materials including 2-D and topological materials. "Because laser picoscopy can be readily combined with time-resolved laser techniques, it may soon become possible to record real movies of electrons in materials. This is a long-sought goal in ultrafast sciences and microscopies of matter" Goulielmakis concludes.
-end-


University of Rostock

Related Radiation Articles:

What membrane can do in dealing with radiation
USTC recently found that polymethylmethacrylate (PMMA) and polyvinyl chloride (PVC) can release acidic substance under γ radiation, whose amount is proportional to the radiation intensity.
First measurements of radiation levels on the moon
In the current issue (25 September) of the prestigious journal Science Advances, Chinese and German scientists report for the first time on time-resolved measurements of the radiation on the moon.
New biomaterial could shield against harmful radiation
Northwestern University researchers have synthesized a new form of melanin enriched with selenium.
A new way to monitor cancer radiation therapy doses
More than half of all cancer patients undergo radiation therapy and the dose is critical.
Nimotuzumab-cisplatin-radiation versus cisplatin-radiation in HPV negative oropharyngeal cancer
Oncotarget Volume 11, Issue 4: In this study, locally advanced head and neck cancer patients undergoing definitive chemoradiation were randomly allocated to weekly cisplatin - radiation {CRT arm} or nimotuzumab -weekly cisplatin -radiation {NCRT arm}.
Breaking up amino acids with radiation
A new experimental and theoretical study published in EPJ D has shown how the ions formed when electrons collide with one amino acid, glutamine, differ according to the energy of the colliding electrons.
Radiation breaks connections in the brain
One of the potentially life-altering side effects that patients experience after cranial radiotherapy for brain cancer is cognitive impairment.
Fragmenting ions and radiation sensitizers
The anti-cancer drug 5-fluorouracil (5FU) acts as a radiosensitizer: it is rapidly taken up into the DNA of cancer cells, making the cells more sensitive to radiotherapy.
'Seeing the light' behind radiation therapy
Delivering just the right dose of radiation for cancer patients is a delicate balance in their treatment regime.
Radiation contamination at a crematorium
Radioactive compounds known as radiopharmaceuticals are used in nuclear medicine procedures to diagnose and treat disease.
More Radiation News and Radiation Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.