Creating an identify card for nanoparticles is now possible! Rather than their birthday, name and place of birth, we can determine their form, their crystalline structure and their environment. This information is essential to better understand and distinguish between them. Researchers at the Institute of Light and Matter (ILM) are therefore working on solving the mysteries of these particles.

Nanoparticles are composed of common materials (gold, silver, silicon, glass) and are extremely small. Researchers study them to find out how these materials' properties are modified at the nanometric scale. The identity card of a gold nanoparticle would obviously not be the same as its silver counterpart.

One of the determining elements in the characterization of a nanoparticle is its capacity to absorb light. A technique known as spatial modulation spectroscopy can be used to determine their spectra. More precisely, researchers observe peaks which correspond to the colours emitted by nanoparticles according to the wavelength of the laser used to excite them. To achieve this, it is not enough to just place a nanoparticle under a laser - it also needs to be made to vibrate to vary the absorption measurements. These results are then used to identify the nanoparticles and determine their spectra.

Thanks to Paolo Maïoli for his contribution.