Blacklight Fluorescence: What Glows and Why

This simulation puts a virtual UV blacklight in a dark room with four real fluorescent materials: a scorpion, a glass of tonic water, a mineral rock and a UV-brightened white shirt. Drag the lamp to aim its invisible UV beam at each object and watch it absorb high-energy UV photons and re-emit lower-energy visible light in its own characteristic color — blue for tonic water's quinine, green for the scorpion's cuticle, orange for the mineral, and blue-white for the detergent-treated fabric. The energy diagram tracks the Stokes shift for whichever material is selected: the absorbed UV photon always arrives with more energy than the emitted visible photon leaves with, the difference lost as heat.