Direct imaging of single gold and polystyrene nanoparticles in the deep ultraviolet

Detecting single nanoparticles has a profound impact across various fields of nanoscience. While optical imaging offers high throughput and low invasiveness, the detection of single dielectric nanoparticles remains challenging in the visible domain due to weak light-matter interactions. Here we demonstrate the significant potential of ultraviolet (UV) microscopy to overcome these limitations. We develop a bright-field UV microscope operating at 285 nm illumination and record the extinction cross-section of single gold and polystyrene nanoparticles. Correlative electron microscopy imaging and Mie theory simulations validate our results. Leveraging on the strong UV absorption of metallic and dielectric nanoparticles, our findings establish UV microscopy as a simple, versatile, and high-sensitivity tool for single nanoparticle analysis.