# Beamed UV sonoluminescence by aspherical air bubble collapse near liquid-metal microparticles

## TL;DR

This paper demonstrates a novel method to generate directed UV-C light beams from aspherical bubble collapse near liquid-metal microparticles, enhancing disinfection efficiency in contaminated water.

## Contribution

It introduces a new approach using aspherical bubble collapse near gallium-based microparticles to produce directed UV-C light beams via sonoluminescence.

## Key findings

- UV fluence exceeds 10 mJ/cm², sufficient for pathogen inactivation.
- Directed UV beam is perpendicular to metal surface due to plasmon interactions.
- Method enables effective water disinfection even with high turbidity.

## Abstract

Irradiation with UV-C band ultraviolet light is one of the most commonly used ways of disinfecting water contaminated by pathogens such as bacteria and viruses. Sonoluminescence, the emission of light from acoustically-induced collapse of air bubbles in water, is an efficient means of generating UV-C light. However, because a spherical bubble collapsing in the bulk of water creates isotropic radiation, the generated UV-C light fluence is insufficient for disinfection. Here, we show that we can create a UV light beam from aspherical air bubble collapse near a gallium-based liquid-metal microparticle. The beam is perpendicular to the metal surface and is caused by the interaction of sonoluminescence light with UV plasmon modes of the metal. We calculate that such beams can generate fluences exceeding $10$ mJ/cm$^2$, which is sufficient to irreversibly inactivate most common pathogens in water with the turbidity of more than $5$ Nephelometric Turbidity Units.