An illuminated water droplet creates an ‘optical atom’

Shining light on water droplets creates an effect similar to what happens in atoms. This helps us understand how atoms work. physical review letter.

If you whisper by the wall in the dome of St Paul’s Cathedral in London, you’ll find that the sound bounces off the dome wall and is heard on the other side. That is why the cathedral dome is called the ‘Whispering Corridor’.

The same effect is light rays Glow in the water droplets. The light ray bounces off the inner wall of the drop many times and circles inside the drop. When its circumference is a multiple of the wavelength of light, a resonance phenomenon occurs, similar to the sound in the dome of a cathedral, and the drop shines brighter.

flashing water droplets

“In our experiments laser light, it turns out that the light is trapped inside the water droplets. As the droplets shrink due to evaporation, they appear to flash each time they are of a size suitable for triggering resonance phenomena,” said the lead author of the new study, a doctoral student in physics at the University of Gothenburg. says student Javier Marmorejo.

Researchers can trap water droplets thanks to Nobel Prize-winning optical tweezers technology Laser beam Aim from two directions.of Laser beam It refracts and scatters inside water droplets, trapping light inside.

The dome of St. Paul’s Cathedral cannot be resized, but water droplets change size as they evaporate. The researchers then discovered how the droplets flashed in a similar manner to what occurs when electrons are ejected from atoms when illuminated by different wavelengths of light. We could also use the analogy of quantum mechanics to explain how resonances (droplet size when scattering is maximum) correspond to atomic energy levels. This makes the droplet a model of the atom, with the added bonus of being able to change its size. It is a model for understanding how atoms work, while providing greater insight into how light scatters.

Useful for pharmaceutical research

“A water droplet is about 100,000 times the size of an atom, so it gives us a model of a visible atom. naked eyeis an “optical atom,” says Javier Marmorejo.

Laser spectroscopy produces data on the energy levels, bonding and structure of atoms and molecules.Similarly, the spectrum of scattered light from water droplets Generate data on real droplets. The researchers say it can be used to measure the evaporation rate of tiny droplets with high precision. This finding can also be applied to liquids other than water and could be useful, for example, in studying aerosol droplets in inhalers used for medication. Researchers also note that the technology offers new ways to analyze water quality.

“Small amounts of contaminants in water change the way water droplets flash, opening up the possibility of quick and easy measurements of chemical or biological contaminants in water droplets,” says Javier Marmorejo.