The G-band is the main Raman mode in graphite and graphene, linked to the planar configuration sp 2 bonded carbon, which is constituting the graphene layers (Application Note). "The band position is pretty much independent of excitation laser frequency" (Application Note). The D-band is the "disorder band" or the "defect band". "This band is linked to the ring breathing mode from sp 2 carbon rings … The band is typically very weak in graphite and is typically weak in graphene as well. If the D-band is significant, it indicates that there are a lot of defects in the material" (Application Note).