INVESTIGATION OF DOUBLE-LAYER STRUCTURE AT PLATINUM IN ACID ELECTROLYTES BY MODULATED IR-SPECTROSCOPY

The electrochemically modulated infrared spectroscopy (EMIRS) is a hig hly sensitive in-situ technique to obtain vibrational spectra of speci es adsorbed on metal electrodes. The contribution discusses the influe nce of several experimental parameters as the electrode potential, the frequency and amplitude of the superposed potential modulation and th e pH value of the electrolyte on the spectra of water molecules within the Helmholtz Double Layer at a platinum surface. The spectra contain significant information about conformational changes of water molecul es, which are coadsorbed by atomic hydrogen on the platinum surface. T he comparison of experimental results to those of theoretical calculat ions with Lagrange formalism indicates that, modulating the potential of a positively charged electrode, a complex molecule structure is var ied at the surface.