Figure 2.

Tunability of the emitted photon energy via the electron energy. (a, b) Numerical (circles) vs analytical (solid lines) results of the radiation power from a single electron in units of power per photon energy per solid angle for a variety of electron energies and fixed polar angles. Different colors represent different electron energies. The polar angles in (b) are chosen such that ϕ = 0 and θ is approximately halfway between the leftmost edge and the peak of the full angular spectrum. Numerical (c) vs analytical (d) results of the full angular spectrum of radiation power from a single electron with energy 5 MeV. All calculations are carried out using the parameters of the reference nanograting¹⁶ with a length along z of 4.65 μm and an electron launched in the z direction with initial height x₀ = 1 nm above the nanograting surface.