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Engineers first observed an avalanche in nanoparticles.

Colombian engineer first noticed an avalanche in nanoparticles

An illustration of a chain reaction process under the photon collapse mechanism, Columbia Engineering researchers have realized in their nanoparticles. In the process, the absorption of a single low-energy photon triggers a chain reaction of energy transfer and absorption events, resulting in a large number of highly excited ions within the nanoparticles, which are released. Energy is released in the release of much higher energy photons. Credit: MikołajŁukaszewicz / Polish Academy of Sciences.

Columbia Engineering researchers today report that they have developed the first nanomaterial to demonstrate the “photon collapse” process, an unmatched combination of behavior and optical efficiency. line Photon collapse as nanoparticles has resulted in many sought-after applications, from real-time high-resolution optical microscopy, accurate temperature and environmental detection and photon detection. Infrared light detection through analog to digital conversion and quantum detection.

“This kind of collapse behavior has never been seen in nanomaterials,” said James Schuck, an associate professor of mechanical engineering, who led the study published today. natureWe study these new nanoparticles at a single nanoparticle level, which helps us prove that collapse behavior can occur in nanomaterials. This great sensitivity can be incredibly transformative. Whether we can sense changes in our chemical environment, such as changes in Or the existence of true molecular strains, we may also detect coronavirus and other diseases. “

The collapse process, a small perturbation event found in a wide variety of phenomena besides snow slides, including champagne bubble bursts, nuclear explosions, strikes, neuron networks, and even The Avalanching financial crisis is a radical example of a nonlinear process in which a change in input or impulse leads to a disproportionate change in the output signal, often oversized. Generally, a large amount of material is required for generating an efficient nonlinear optical signal, and this is the case with photon collapse to date.

In optics, photon collapse is a process by which the absorption within crystals of a single photon results in a multitude of emission. The researchers used photon collapse in specialized lasers, where photon absorption triggers a chain reaction of optical events that ultimately led to the efficient copying.

What is remarkable to researchers is that not only one photon is absorbed. But only led to a large number of photons emitted It also results in astounding properties. The emitted photons are “upside down”, each having a higher energy (blue) than a single photon absorbed. Scientists can use the wavelengths in the infrared region of the light spectrum to generate a large number of high-energy photons, much better at stimulating the desired chemical changes, such as killing cancer cells in target locations deep in every tissue. Where the nanoparticles collapse

Photon collapse behavior (PA) gained great attention more than 40 years ago, when researchers recognized that severe nonlinearity could have broader implications for a number of technologies, ranging from lasers with transducers. They are powerful all the way to photonics, optical sensors and night vision devices. The PA’s behavior is similar to that of transistors in electronics in that a slight change in the input voltage results in a significant change in the output current, providing the signal amplification required for the operation of almost all electronic devices. Some materials can act as optical transistors.

PA has been studied especially in lanthanide-containing (Ln) materials because of its unique optical properties that allow it to store light energy for a long time. However, achieving PA in an Ln system is difficult – it requires a cooperative interaction between many Ln ions while also controlling the depletion pathway, so it is limited to large amounts of material and aggregates, often at Low temperature

These limitations have curtailed fundamental studies and the use of PA to a specific role in photonic science, and have made researchers focus only over the past decade on other turning mechanisms in the development of the material. Despite the unmatched advantages of a PA

In the new study, Schuck and his international collaborator team included Bruce Cohen and Emory Chan’s group (The Molecular Foundry, Lawrence Berkeley National Lab), Artur Bednarkiewicz (Polish Academy of Sciences) and Yung Doug Suh ( Korean research institute Of chemical technology and universities Sungkyunkwan) showed that by adopting some important nanoparticle design innovations, such as the content and the selected lantanide type, they were able to successfully synthesize a new 20nm nanocrystalline that demonstrated its collapse. Of photons and extreme nonlinearity

The team observed that the nonlinear optical responses in these collapsing nanoparticles scale to the 26th force of the incident light intensity.A 10% change in incident light changes the light emitted by more than 1,000. % This nonlinearness exceeds the previously reported response in the nanocrystallantanide. This extraordinary response means that the collapsing nanoparticles (ANP) show great promise as a sensor, as small changes in the local environment can make the particles emit 100-10,000 times brighter, the researchers said. It was also found that large nonlinear responses in ANP allow deep sub-wavelength optical imaging (with ANP used as a fluorescence probe or contrast agent) using confocal microscopy. Scan only

Shine Light: Nanoparticles collapse, breaking barriers to real-time cell imaging.

Left: Experimental PASSI (photon avalanche single-beam super-resolution imaging) image of thulium-doped avalanche nanoparticles separated by 300 nm. Right: PASSI simulation of the same material. Credit: Berkeley Lab and Columbia University.

“ANP allows us to overcome the resolution diffraction limit for optical microscopes with large margins, and basically they do it free due to steep non-linear behavior,” Schuck explains.

Changhwan Lee, the study’s lead author, who holds a doctorate degree. The students in Schuck’s group added: “Extreme nonlinearity in a single ANP turns a conventional confocal microscope into an imaging system. The newest superresolution “

Now, Schuck and his team are working on a way to use this unprecedented non-linear behavior to detect environmental changes such as fluctuations in temperature, pressure, humidity, with a sensitivity that has not yet been achieved.

“We are very excited about our findings,” Schuck said. “We expect them to lead to revolutionary new applications in sensing, imaging and light sensing. It is proven to be vital to future optical data processing chips with ANP delivering a typical amplifier-like response and a single small area. Transistors in electronic circuits “

The study is titled “Giant, non-linear optical response from nanoparticles that collapse photons”

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More information:
Giant, non-linear optical response from photon-bombed nanoparticles nature (2021). DOI: 10.1038 / s41586-020-03092-9, www.nature.com/articles/s41586-020-03092-9.

Offered by Columbia University School of Engineering and Applied Science

Reference: Engineers observe avalanches in nanoparticles for the first time (2021, January 13) .Retrieved January 13, 2021 from https://phys.org/news/2021-01-avalanches-nanoparticles.html.

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