Hi! Rather fundamental question, but the more you research something the farther down a rabbit hole you can go. I'll use a few examples:

-I know that glass absorbs UV light as it has enough energy to excite valence electrons or an electron to the valence shell. The energy that is released by the electron as it goes back to ground state is given off as what? UV radiation of the same energy? If so, then wouldn't that energy just transmit through the glass? Do the valence electrons leave their orbit with all this energy?

-The UV light that is hitting my red fence right now. The visible light from the sun with the right amount of energy to excite electrons into the valence shell emit the red frequency when they drop back down to ground. The UV light that hits the valence / lower energy electrons are excited enough to leave an exist as free radicals, yes? Is this sea of free radicals constantly feeding the now empty valence shells? I picture a massive release of free radicals upon exposure to UV light, so I am curious where these free radicals go.

Basically, I understand what happens when radiation of the visible spectra interacts with electrons. It's the UV radiation interaction that has me asking questions.

Thanks!