What happens in chemicals that makes them photosensitive? Like I know that chemicals get affected by temperature, and their molecules start moving faster, so is photosensitivity basically similar that when light particles come in, something happens? If so, what exactly happens?
In: Chemistry
When a molecule absorbs light an electron is moved from the ground state to a higher energy “excited state”. From here, the electron can do one of three basic things. First is nonradiative decay, where the electron makes its way back to the ground state and the energy difference between the ground and excited state is released as heat. The next thing that can happen is radiative decay. Here the electron makes its way back to where it came from, but the excess energy is given off as light. The third thing the molecule can do is react. Depending on the molecule, while the electron is in the excited state it is unpaired, so it can do various things from there, such as creating a leaving group (how diazos create carbenes), it can simply cleave off to form a radical (Norrish), or it can react in the excited state where the molecule will have some diradical character. There are many other things it can do as well. Photochemistry is complicated.
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