ok, tired as i am lets see,,, suprised stevie hasn't answered this yet.
when the electron moves the the outer most shell the energy state gets greater if that atom along with its mass size, as the electron moves to the outer most shelll photons are consumed. As the atom looses its energy state and it will the atoms get smaller, as the atom gets smaller the electron will jump shells, moving closer and closer to the nucleus. as the electrons jump shells moving in closer to the nucleus a photon is released in the form of light.
Cold atoms, the electrons are closer to the nucleus, protons. hot, warm atoms, the electrons are further away from the nucleus, protons. The temp of the atom will determine its resonate freq, if you know the freq you want to put that atom in by using photon injection you must apply that photon at that freq.
For example, cold hydrogen may be resonating at 300 nanometers, one may add a 500 nanometer led light to force that atom to take on a resonate freq of 500 nanometers, increasing its mass energy state, and temp range. one forced the atom into a known state. If your not on the proper freq that the atom can understand, its possible the atom will totally ignor the photon injection and instructions all together.
you can also see how Xrays work, what it is they detect and why it is they ignore your skin.