Laser combined device integration helps light up-frequency nano-pharmaceutical research results improve

[ China Pharmaceutical Network Technology News ] Naik's research at Stanford University was inspired by the groundbreaking work of Professor NaomiHalas and Professor Peter Nordlander at the Nanophotonics Laboratory, who have shown that materials that excite plasmons have also inspired "Hot carriers" - electrons and holes - are inside the material (holes are vacancies that occur when an electron is excited to a higher state, causing it to generate a positive charge.)

(Gururaj Naik is developing a technology for upconverting light using a laser to excite devices that combine plasmonic metal and semiconductor quantum wells. Image: Tommy LaVergne/Lees University)

The experiment led by Gururaj Naik, an assistant professor of electrical and computer engineering, combines plasmonic metal and semiconductor quantum wells to increase the frequency of light and change its color.

On nanoscale samples, Naik, a postdoctoral fellow at Stanford University, developed a custom-made tower that was hit by green light to produce a higher-energy blue glow. He said: "I use low-energy photons and convert them into high-energy photons."

Naik said that effective light up-conversion may cause solar cells to invert infrared sunlight and convert it into electricity or help sensitive nanoparticles to treat diseased cells.

The study was published in the American Chemical Society's "Nano Letters."

Magic occurs inside the tower, and the tower measures the range of approximately 100 nanometers. When excited by light of a specific wavelength, the gold dots on the tip of the tower convert the light energy into a plasma, like the ripples on the pond, the plasma energy waveform is rhythmically sputtered across the gold surface. The plasmon lifetime is short-lived. When they decay, they release their energy in one of two ways; they either excite a photon in the light, or pass it to an electron - a "hot" electron - To generate heat.

In Naik's research at Stanford University, inspired by the groundbreaking work of Professor NaomiHalas and Professor Peter Nordlander at the Nanophotonics Laboratory, they have shown that materials that excite plasmons also excite "hot carriers" - Electrons and holes - inside the material (holes are vacancies that are generated when an electron is excited to a higher state, causing its atom to generate a positive charge.)

Professor Naik, who joined the University of Rice University a year ago, said: "Plasma is really great at compressing light to nanoscale." "But it's all at the expense of something." Halas and Nordlander said that you can extract optical losses in the form of electrical energy. My idea is to convert electrical energy back into the form of light."

He used a tower designed with a rotating layer of gallium nitride and indium gallium nitride, and the top layer was coated with a thin layer of gold and surrounded by silver. Naik's strategy is to direct hot electrons and hot holes as gallium nitride and gallium indium nitride substrates for electron-trapping quantum wells, rather than allowing hot carriers to escape. These wells have a fixed band gap that isolates electrons and holes until they recombine across the band gap with sufficient energy and release photons at a higher frequency.

According to Naik, the efficiency of today's upconverters for on-chip communication, photodynamic therapy, security and data storage ranges from 5% to 10%. Quantum theory confirms that efficiency can be as high as 50% ("because we absorb two photons to emit a photon"), but he says that 25% is the actual goal of his method.

Naik said his equipment can be adjusted by changing the size and shape of the particles and the thickness of the layers. He said: "Upconverters based on lanthanides and organic molecules emit and absorb light at a set frequency because they are fixed at atomic or molecular energy levels. "We can design quantum wells and adjust their energy gaps to Photons are emitted in the frequency range we want, and metal nanostructures that are absorbed at different frequencies are similarly designed. This means that we can design absorption and emission almost independently, which was previously impossible.

After working with Stanley Dionne to publish a theoretical article prepared for his experiments, Naik established and tested the prototype concept of the tower array while working at Stanley Dionne's Stanford University laboratory.

“This is a solid-state device,” Naik said of the prototype. “The next step is to make individual particles by coating the quantum dots with metals of the appropriate size and shape.”

He said that these have shown potential as medical contrast agents or drug delivery vehicles. Naik said: "Infrared light has deeper penetration into the tissue, and blue light can cause the necessary reactions for drug delivery.", "People use the upconverter to deliver the drug to the desired part of the body and transmit it from the outside to the infrared. The drug makes the drug active.

He said that particulate matter can also make an invisible ink. “You can write with an upconverter, no one will know what you are writing until you are illuminated with high-intensity infrared and the color of the word is converted to visible light.”

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