  One of the most important tools in modern science is the analysis of
electromagnetic properties via spectroscopy. The various types of spectroscopy
can be classified by the underlying type of interactions between energy and
material. In this paper we demonstrate a new class of spectroscopy based on
Casimir interactions between a solid investigated object and a reference
surface embedded in an environmental liquid medium. Our main example is based
on the measurement of Hamaker constants upon changing the concentration of an
intervening two-component liquid, where we demonstrate a possible
reconstruction algorithm to estimate the frequency-dependent dielectric
function of the investigated particle.
