We have very frequent questions regarding the "microscopic" details of the process of reflection, the cause of transparency, etc. in solids. In many cases, people often still think of this as being caused by "atomic transition", neglecting the fact that these are solid state physics and not occurring on individual, isolated atoms. This is a http://www.eknigu.org/get/P_Physics...ties Of Solids (lecture notes)(198s)_PS_.pdf", written by one of the giants in the field of material science/condensed matter physics - Mildred Dresselhaus. As one can see, the process of absorption and reflection isn't trivial, but it always involves a LARGE conglomerate of particle and atoms, making it NOT an isolated, single-atom process. Zz.