Scientists discover a new process to convert visible light into infrared light



Scientists discover a new process to convert visible light into infrared light

Billions of molecular bulbs, powered by invisible infrared photons, generate visible light. Credit: Melissa Ann Ashley

Scientists at Columbia University, in collaboration with Harvard researchers, have succeeded in developing a chemical process to convert infrared energy into visible light, allowing harmless radiation to penetrate living tissue and other materials without the damage caused by exposure. in high intensity light.

His research is published in the January 17 issue of Nature.

"The findings are exciting because we were able to perform a series of complex chemical transformations that generally require high-energy visible light using a non-invasive infrared light source," said Tomislav Rovis, a chemistry professor at Columbia and co-author of the study. "One can imagine many potential applications where barriers prevent the control of matter, for example, the research is promising to improve the reach and efficacy of photodynamic therapy, whose full potential for cancer treatment has not yet materialized" .

The team, which includes Luis M. Campos, an badociate professor of chemistry at Columbia, and Daniel M. Congreve of the Rowland Institute at Harvard, conducted a series of experiments with small amounts of a novel compound that, when stimulated by the Light, can Mediate in the transfer of electrons between molecules that would otherwise react more slowly or not react.

Its approach, known as upstream triplet fusion, involves a chain of processes that essentially fuses two infrared photons into a single photon of visible light. Most technologies only capture visible light, which means that the rest of the solar spectrum is wasted. The up-conversion of the triplet fusion can capture low-energy infrared light and convert it into light that is then absorbed by the solar panels. Visible light is also easily reflected on many surfaces, while infrared light has longer wavelengths that can penetrate dense materials.

"With this technology, we were able to adjust the infrared light to the necessary and longer wavelengths that allowed us to pbad non-invasively through a wide range of barriers, such as paper, plastic molds, blood and tissues," Campos said. . The researchers even pulsed the light through two strips of bacon wrapped around a flask

Scientists have long tried to solve the problem of how to obtain visible light to penetrate the skin and blood without damaging internal organs or healthy tissue. Photodynamic therapy (PDT), used to treat some cancers, uses a special medication, called a photosensitizer, that is activated by light to produce a highly reactive form of oxygen that can kill or inhibit the growth of cancer cells

Current photodynamic therapy is limited to the treatment of localized or surface cancers. "This new technology could bring the PDT to areas of the body that were previously inaccessible," Rovis said.

"Instead of poisoning the whole body with a drug that causes the death of malignant cells and healthy cells, a non-toxic drug combined with infrared light could selectively attack the tumor site and irradiate cancer cells."

The technology could have a powerful impact. Infrared light therapy can be instrumental in the treatment of a number of diseases and conditions, including traumatic brain injuries, damaged spinal nerves and marrows, hearing loss and cancer.

Other potential applications include remote management of chemical storage, solar energy production and data storage, drug development, sensors, food safety methods, mouldable compounds that mimic bone and processing. microelectronic components.

Researchers are currently testing photon conversion technologies in additional biological systems. "This opens up unprecedented opportunities to change the way light interacts with living organisms," Campos said. "In fact, we are currently using up-conversion techniques for tissue engineering and drug delivery."


Explore further:
Fluorescence of upward conversion in organic metal structures.

More information:
Benjamin D. Ravetz et al, Catalysis by photoredox that uses infrared light by upward conversion of the fusion of the triplets, Nature (2019). DOI: 10.1038 / s41586-018-0835-2

Journal reference:
Nature

Provided by:
University of Colombia


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