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New color photography using high-efficiency probes can super-focus white light into a 6-nanometer spot for nano-level color imaging

Scientists have developed new materials for the next generation of electronic products. This material is so small that not only are they indistinguishable when tightly packed, but even the most powerful optical microscope cannot reflect enough light to show details such as colors. . For example, under an optical microscope, carbon nanotubes look gray. Since it is impossible to distinguish the subtle details and differences between the various parts of nanomaterials, it is difficult for scientists to study their unique properties and find ways to perfect them for industrial use.

In a new report by Nature Communications, researchers at the University of California, Riverside describe a revolutionary imaging technique that compresses light into nanometer-sized spots. It maintains this light at the end of the silver nanowire like a Hogwarts student practicing the "Lumos" spell, and uses it to reveal previously invisible details, including colors. 

This advancement will increase the resolution of color imaging to an unprecedented level of 6 nanometers and will help scientists observe nanomaterials in sufficient detail to make them more useful in electronics and other applications.

Associate Professors Liu Ming and Yan Ruoxue of the Malan and Rosemary Burns School of Engineering at the University of California, Riverside, developed this unique tool using the hyperfocus technology developed by the team. This technique has been used in previous work to observe the vibration of molecular bonds with a spatial resolution of 1 nanometer, without the need for any focusing lens. 

In the new report, Liu and Yan modified a tool that measures signals across the entire visible wavelength range, which can be used to render colors and depict the electronic energy band structure of objects, not just molecular vibrations. The tool squeezes the light emitted by the tungsten lamp into silver nanowires with near zero scattering or reflection, where the light is carried by the free electron oscillating waves on the silver surface. 

The concentrated light leaves the tip of the silver nanowire with a radius of only 5 nanometers in a tapered path, just like a beam from a flashlight. When the tip passes an object, its effect on the shape and color of the beam is detected and recorded. 

"It's like using a thumb to control a hose to spray water," Liu said. "You know how to get the desired spray pattern by changing the position of the thumb. Similarly, in the experiment, we retrieve the blocking 5 by reading the light pattern. The details of the object of the nano-sized light nozzle." 

The light is then focused into the spectrometer, where it forms a tiny ring. By scanning the probe over an area and recording the two spectra of each pixel, researchers can use color to develop absorption and scattering images. Carbon nanotubes that were initially gray received their first color photos, and individual carbon nanotubes now have the opportunity to show their unique colors.

"Atomic-level smooth, sophisticated silver nanowires and their almost non-scattering optical coupling and focusing are essential for imaging," Yan said. "Otherwise, there will be strong stray light in the background, which will ruin the entire work."

Researchers predict that this new technology can become an important tool to help the semiconductor industry manufacture uniform nanomaterials with consistent properties for use in electronic devices. The new full-color nanoimaging technology can also be used to improve the understanding of catalysis, quantum optics, and nanoelectronics.

Liu, Yan, and Ma joined Xuezhi Ma’s research, and he participated in the project in his doctoral research at the University of California, Riverside. The researchers also include UCR students Qiushi Liu, Ning Yu, Da Xu, and Sanggon Kim; Liu Zebin and Jiang Kaili from Tsinghua University; and Professor Huang from the University of California, Los Angeles. The paper titled "Using nano-scale white light sources for 6 nm super-resolution optical transmission and scattering spectral imaging of carbon nanotubes" is available here.  

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