The optical and the acoustic thicknesses of protein layers during adsorption were simultaneously determined by a combination of surface plasmon resonance spectroscopy and quartz crystal microweighing. Coupling of the surface plasmon was achieved by etching a diffraction grating into the quartz surface prior to the deposition of the metal electrode. The evolution of the acoustic and the optical thickness was markedly different, which is attributed to surface roughness and partial coverage.
Authors: Alexander Laschitsch, Bernhard Menges, and Diethelm Johannsmann
Source: Applied Physics Letters