 The resulting wavelength is 8.3386 angstroms (0.83386 nm) which corresponds to a photon energy of 1486.7 eV.Aluminum Kα X-rays have an intrinsic full width at half maximum (FWHM) of 0.43 eV, centered on 1486.7 eV ("E"/Δ"E" = 3457).For a well–optimized monochromator, the energy width of the monochromated aluminum Kα X-rays is 0.16 eV, but energy broadening in common electron energy analyzers (spectrometers) produces an ultimate energy resolution on the order of FWHM=0.25 eV which, in effect, is the ultimate energy resolution of most commercial systems.