AS previously reportedThe bright iridescent colors in things such as peacock feathers and butterfly wings do not come from pigment molecules but by how they are structured. The stairs of Chitina (a polisaccaride common to insects) in the butterfly wings, for example, are arranged as roof tiles. Essentially, they form a diffraction gridExcept for the photonic crystals, they only produce certain colors or wavelengths, while a diffraction grid will produce the entire spectrum, just like an prism.
In the case of peacock feathers, they are the normal periodic nanostructures of the Barbules—The components similar to fiber composed of ordinated melanin rods coated with keratin-that produce the iridescent colors. Different colors correspond to different spacing of the barbules.
Both are natural examples of what physicists call Fotonic crystals. Also known as Banda’s photonic materials, photonic crystals are “tuning”, which means that they are precisely ordered in order to block some wavelengths of the light while they let others pass. Alter the structure by changing the size of the tiles and crystals become sensitive to a different wavelength. (In fact, the rainbow tonchio can control Both the size of its stairs and the quantity of chitina is used to perfect those necessary colors.)
Even better (from the point of view of applications), the perception of color does not depend on the visualization corner. And the stairs are not just for the aesthetics; They help protect the insect from the elements. There are different types of Artificial photo crystalsBut obtaining a better and more detailed understanding of how these structures grow in nature could help scientists design new materials with similar qualities, such as iridescent windows, self -supportable surfaces for cars and buildings or even waterproof fabrics. The paper currency could incorporate encrypted iridescent motifs to thwart counterfeiters.
There have been previous examples of random laser emissions in all of stains Bovine bones AND blue coral skeletons TO insect wings, parrot feathersAND human tissueas well Iridifori salmon. The authors of this most recent study were interested in the fact that they could produce similar laser emissions using peacock feathers and, hopefully, identify the specific mechanism.
It was not difficult to get peacock feathers, given how popular they are for decorative and artistic purposes and crafts, but the authors have made sure that none of the feathers used in their experiments contained impurities (such as dyes). They cut any excess lengths of barbes and mounted the feathers on an absorbent substrate. They then infused the feathers with common dyes by pipette the tincture solution directly on them and letting them dry. The feathers have been colored several times in some cases. Then they pumped the samples with light pulses and measured any resulting emissions.
The team observed laser emissions in two distinct wavelengths for all the color regions of the eyes of the feathers, with the green regions that emit the most intense laser light. However, they did not observe any laser emission from feathers that have only been colored once, in the sample feathers undergoing multiple wet and complete drying cycles. This is probably due to the best diffusion of dye and solvent in the barbules, as well as a possible loosening of the fibrils in the keratin sheath.
The authors have not been able to identify precise microstructures responsible for the laser; It does not seem to be due to keratin -covered melatonin rods. Co -author Nathan Dawson of Florida Polytechnic University suggested to science Those protein granules or small similar structures within the feathers could work as a laser cavity. He and his colleague think that one day, their work could lead to the development of biocompatible laser that could be incorporated safely in the human body to detect, imaging and therapeutic purposes.
This story originally appeared on Ars Technica.