Layer formation by 1,7-diphosphono-heptane

Abstract

Surface modification of polycrystalline ARMCO iron and an Fe(110) single crystal was performed using a solution of 1,7-diphosphono-heptane (DPH). The changes of the surface properties were studied by subtractively normalised interfacial Fourier transform infrared spectroscopy (SNIFTIRS), scanning tunneling microscopy (STM) and electrochemical impedance spectroscopy (EIS). The immersion of the surfaces into DPH solution resulted in a build up of an ordered thin multimolecular layer after a few hours of continuous adsorption. The orientation of the DPH molecules was influenced by the supporting electrolyte and the electrode potential. The treatment in the absence of oxygen resulted in a lower corrosion protection effect compared to diphosphonate layer formation in an atmospheric environment.

Keywords

• adsorption
• diphosphonate
• eis
• self-assembling molecules
• sniftris
• stm