Polymer chains attached by one end to an impenetrable surface at high
coverage exemplify a tethered layer of mesoscopic dimensions. At equil
ibrium, thermal fluctuations of the segment density profile of the bru
shlike layer reflect the tethered chain dynamics; the probing of these
fluctuations by evanescent-wave dynamic light scattering is reported.
By utilizing a set of terminally attached layers with thicknesses (L(
0)) from 45 to 130 nanometers, it was found that there is a preferred
wavelength of order L(0) of these fluctuations with a concurrent slowi
ng down of their thermal decay rate. This technique could open the rou
te for the investigation of the largely unexplored area of polymer sur
face dynamics.