Using the Drude-free electron theory the polarization parameter P due
to interband transitions as well as the optical mass mo and the relaxation time τ
of the electrons could be obtained using the estimated values of the real-and
imaginary - part of the dielectric constant εr, εi' estimated by obtained
attenuated total reflection-measurements for the boundary Ag/air. It has been
clear demonstrated that our estimated values P, mo, τ are in consistent with
published data. This circumstance has the consequence to obtain a general
identities to estimate ε ε r
f
i
, f for silver films in a comparatively wide spectral
range. Furthermore the limit energy for the surface plasma oscillations
hωs = hωp/ 1 + P = 3.66 eV corresponds to infinite values of the K-vector of
the surface plasma waves. In this case both the phase - and the group – velocity
Vp, Vg of the surface waves must be equal to zero. In addition the energy limit
of interband transitions could be estimated as 3.974 eV. A derivation of two
formulae for the phase- and group- velocity of the surface waves could be
obtained from the dispersion relation (ω,k). In addition the energetic parameter
β and the wave-number parameter χ could be estimated with good accuracy.