19-10-2010: Optical antennas made of gold nanoparticles can enhance the sensitivity of photoluminescence and vibrational spectroscopy, according to research published in Chemical Science.
In traditional microscopy and spectroscopy, components such as lenses, mirrors and diffractive elements are used to control and focus the optical radiation. This relies on the wave nature of the radiation and means the smallest volume to which the radiation can be localised, and so the technique’s sensitivity, is limited by diffraction.
Now Lukas Novotny and colleagues at the University of Rochester, USA, have taken inspiration from radio wave manipulation and designed an optical antenna that can boost the interaction between light and the particle being studied. The fluorescence of a single molecule can be enhanced by more than a factor of 10 using this technique. The optical antenna, which consists of a single colloidal gold nanoparticle on the end of a pointed dielectric fibre, replaces a conventional focusing lens or objective, so the incoming light can be focused to dimensions smaller than the diffraction limit.
As well as improving chemical and biological sensing, the technique holds promise for resolving open questions in surface enhanced Raman scattering and fluorescence, says Novotny.
Original publication:Palash Bharadwaj, Ryan Beams and Lukas Novotny, Chemical Science, 2010
Scientists in France have produced hematite using a bacterial pathway for use as an electrode material in Li-ion technologies.
Currently, most commercial electrode materials for Li-ion technologies are prepared using the ceramic method, which requires long heating periods at high temperatur ... more
An international research team has shown that that the power conversion efficiency of sea tangle extract is comparable to platinum in solar cell electrodes.
Dye-sensitized solar cells (DSCs) are quickly becoming a widespread and affordable alternative to photovoltaic solar cells. The electr ... more
An international team of researchers has used gelatin as their starting material to make a fuel cell catalyst.
The team used gelatin to make doped-carbon electrocatalysts that could be a potential replacement for platinum in fuel cells. To make the catalyst, they mixed iron and magnesium in ... more
The search for sources of clean energy is becoming increasingly urgent as the supply of available energy from fossil fuels decreases and concerns increase about their environmental impact. Alternative sources of clean energy, such as solar energy and biofuels offer great potential; however ... more
The RSC is a leading international publisher of highly regarded journals and books in the chemical sciences. The RSC is also the professional body for chemists with a global membership of over 46,000. more
Polymers -- the essential component of plastics -- are found in countless commercial, medical, and industrial products. Polymers that are porous are called foam polymers and are especially useful because they combine light weight with rigid mechanical properties. Now a researcher at the Uni ... more
Researchers at the University of Rochester have measured for the first time light emitted by photoluminescence from a nanodiamond levitating in free space. In a paper published in Optics Letters, they describe how they used a laser to trap nanodiamonds in space, and – using another laser – ... more
A new type of nanoscale engine has been proposed that would use quantum dots to generate electricity from waste heat, potentially making microcircuits more efficient.
"The system is really a simple one, which exploits certain properties of quantum dots to harvest heat," Professor Andrew Jor ... more