Spin chemical physics of graphenet exhibited in the previous chapters and related to the main features of its physics and standard chemistry as well as mechanochemistry and topochemistry all the issues related to the ground state,  would be incomplete if we do not concern,  at least briefly,  peculiarities related to the excited state. Raman s c a t t e r i n g , p h o t o l u m i n e s c e n c e , $ scattering,\,\,photoluminescence, $ https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781315229270/58c6e982-ead4-4b97-a171-3b8ca312ff9a/content/inline-math12_1.tif"/> photochemistry nonlinear optics,  to name a few,  are usually the main topics of the issue. As in the previous cases,  inherent features of graphene clearly exhibit themselves in its optics and spectroscopy. Particularly it concerns Raman scattering and photoluminescence,  which are the most demanded among other photonic events. The former confidently takes place as the most required testing techniques and is widely used. Important that Raman spectroscopy is equally applicable to graphene in each form. Oppositely photoluminescence is peculiar only to certain forms of graphene known as graphene quantum dots (GQDs). It is connected with the fact that macroscopic graphene crystal does no fluoresce due to the lack of energy gap in its electron spectrum. However,  graphene sheets of nanometer size emit light in the visible regions of the spectrum due to opening the gap. This clearly evident effect of quantum confining stimulated the attribution of nanosize sheets to quantum dots and then to GQDs.