EFFECT OF APPLIED POTENTIAL UPON THE IN-SITU STRUCTURE OF SELF-ASSEMBLED MONOLAYERS ON GOLD ELECTRODES

Polarization modulation Fourier transform infrared reflection absorpti on spectroscopy (PM-FTIRRAS) has been utilized to study the in situ st ructure of octadecanethiol when adsorbed to gold electrode surfaces an d with the application of potential to the substrate. It is found that applied potential has little effect upon the spectrum of the monolaye r in the presence of D2O solutions containing 0.10 M NaClO4. The prese nce of an acetonitrile solution contacting the monolayer leads to smal l changes in the infrared spectrum relative to that seen in D2O soluti ons, suggestive of some small disordering of the monolayer caused by t he presence of the acetonitrile. With the application of potential, ho wever, the infrared peak positions for the methyl and methylene modes return to the positions observed in the pseudo-crystalline ex situ spe ctrum, suggesting that the applied potential has an organizing effect upon the monolayer in the acetonitrile solutions.