  Photopyroelectric spectroscopy (PPE) was used to study the thermal and
optical properties of electropolymerized melanins. The photopyroelectric
intensity signal and its phase were independently measured as a function of
wavelength, as well as a function of chopping frequency for a given wavelength
in the saturation part of the PPE spectrum. Equations for both the intensity
and the phase of the PPE signal were used to fit the experimental results. From
the fittings we obtained for the first time, with great accuracy, the thermal
diffusivity coefficient, the thermal conductivity and the specific heat of the
samples, as well as a value for the condensed phase optical gap, which we found
to be 1.70 eV.
