Figure 1. Illustration of the plasmon emission from charge carriers in graphene via a 2D Čerenkov process.

(a) GP emission in graphene from a hot carrier flowing inside it. The hot carrier (white arrow marking a transparent-blue arch shape) excites GPs that propagate sideways (glowing red-blue bars) along the graphene surface (plotted on the yellow–orange–red substrate). The Čerenkov angle into which the GPs are emitted is denoted by θ (defined between the wiggling red arrows and the z axis, which is the direction of motion of the hot carrier). (b) A diagram describing the GP emission process from a hot carrier in graphene.