what must happen for light to change a material?

Light changes a material when photons from the light are absorbed by its atoms or molecules, transferring energy that excites electrons to higher energy states or converts to thermal energy, heat, or chemical alterations. This absorption requires the light's photon energy—determined by its wavelength or frequency—to match the specific energy difference needed for electronic transitions in the material's atomic structure. For instance, materials can bleach, fluoresce, melt, or undergo photochemical reactions if the incoming light energy aligns precisely with these vibrational or electronic frequencies.