Optical absorption in aluminium and the effect of temperature

Measurements of the optical absorption of clean evaporated aluminium films have been made at several different temperatures and the results interpreted in terms of the theory of parallel band absorption. Values of the Fourier coefficient of the pseudopotential mod U200 mod have been derived and its temperature variation satisfactorily explained. The derived value of this coefficient for 0 K is 0.79+or- 0.01 eV which is somewhat higher than that obtained from Fermi surface data, but the difference may in part be due to an energy dependence of the coefficient. Values of optical mass, interband and Drude relaxation times at the different temperatures have been derived. Some data appropriate to partially disordered films are also presented.