| Over
the past
few decades, the investigation of the dynamics of the charge excitation
spectrum acquired a lot of importance in order to obtain relevant
information about the nature of several ground states, which are of
interest in the ongoing solid state physics research. The investigation
of the optical response can be considered as complementary and
alternative to other methods (like, e.g., transport and thermodynamic
as well as photoemission techniques). Nowadays, it is possible to study
a very broad spectral range of the excitation spectrum, and various
energy scales, which are essential for the full understanding of the
properties of the studied materials, can be identified. |
