This is similar to what fluorescent lights do. If you've ever broken a fluorescent bulb, you'll notice a powdery coating on the inside of the glass, which is th

This is similar to what fluorescent lights do. If you've ever broken a fluorescent bulb, you'll notice a powdery coating on the inside of the glass, which is the phosphor coating that actually absorbs the violet/ultra-violet light of the excited mercury vapor and then re-emits it as visible light.