What is a type of light emission that relies upon a delay between excitation and de-excitation providing an afterglow?
Answer . You are talking about a glow-in-the dark material. It is called phosphorescent. The same idea, light being absorbed and re-emitted at a different frequency - has… two main types. If it happens immediately, it is "fluorescent" (think highlighters in a black light) If there is a delay, it is "phosphorescence." Both effects and the delay in the second, are the result of quantum mechanics. ( Full Answer )