Organophosphonates characterization using MP-SPR
Application Note #150

SAM thicknesses: vinylphosphonic (VPA), octylphosphonic (OPA), and tetradecylphosphonic acid (TPA).
Phosphonic acids adsorption behavior was studied using Multi-Parametric Surface Plasmon Resonance (MP-SPR). Tetradecylphosphonic acid (TPA) adsorption onto differently treated gold surfaces was measured. Piranha and ammonia/hydrogenperoxide treatments were found to be the most optimal for the SAM formation. TPA, vinylphosphonic acid (VPA), and octylphosphonic acid (OPA) adsorption onto the piranha treated surface was studied, and the thickness and the refractive index of the deposited layers were determined. The SAMs were 0.68 nm (VPA), 1.41 nm (OPA) and 1.73 nm (TPA) thick, and thicknesses were in good agreement with the expected molecular length.