Plasmon Damping in Metals

A report is given of a theoretical and experimental investigation into the degree of plasmon damping in metals as a function of momentum transfer. A previous theoretical result by DuBois is corrected and extended by taking into account polarization effects. Measurements are reported of the change in half-width ΔE1/2 of the dispersed {≈}15-eV aluminum plasmon energy-loss peak, excited by 20-keV electrons, as a function of electron scattering angle θ. The results can be expressed in the form ΔE1/2=A+Bθ²+Cθ⁴, and there is good agreement between the values of B and C obtained from the revised theory and those found experimentally.