  We study the viscoelasticity of surface polymer monolayers by measuring the
dynamics of thermal concentration fluctuations with surface light scattering.
For various systems of proteins and synthetic polymers we find a semi-dilute
regime in which both the elastic and viscous components of the dilational
modulus show power law dependencies on the concentration. Surprisingly there is
a universal relationship between the exponents for the two components: the
viscosity scales with a power double that of the elasticity. These results
cannot be explained on the basis of theory developed for bulk systems, and a
simple explanation for the singular 2d behavior is suggested.
