One advantage of the quantum dot is that, compared to many other fluorescent
materials, excited states have relatively long lifetimes (10 ns). What does
this mean for the spread in the energy of the photons emitted by quantum dots?
(a) Quantum dots emit photons of more well-defined energies than do other
fluorescent materials. (b) Quantum dots emit photons of less well-defined
energies than do other fluorescent materials. (c) The spread in the energy is
affected by the size of the dot, not by the lifetime. (d) There is no spread
in the energy of the emitted photons, regardless of the lifetime.
