Phosphorescence and Fluorescent Materials and E = hf - AQA A Level Physics

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence.

Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after. So you have a mixture here in this demo.

The photons in the UV part of the spectrum with a large energy or E = hf will excite atomic electrons which move up a couple of transitions. Then sometime later they will de-excite and emit visible photons of distinct colours which are then visible. Also transition can occur by vibrational relaxation which does not emit a photon.

See how the UV tube excites and also the purple / UV laser. It is confusing as the laser and UV source emit a bit of purple as well (which you can see of course).