Surface Enhanced Raman Scattering(SERS) of water molecules adsorbed at electrochemically roughened silver electrode surface was studied with controlling various parameters of SERS.
Effect of alcohol on SERS of water was examined with adding ethanol at various times of the reduction period and the major role of ethanol was found to be a hydrogen bond breaking.
The excitation profiles of SERS of water in both KCl 0.25M/ water(1)/ ethanol(1) system and KCl 1M/water system were obtained by measurement of the SERS spectra using 10 excitation wavelengths from 457.9nm to 647.1nm. The excitation profile confirms SERS intensity increasing with longer wave-length which may be interpreted as due to a resonance type excitation of silver adatoms.
The irreversible loss of SERS intensity is for a quantitative analysis of the long time tail behaviour and well fitted by the 2-dimensional random walk model. The adatoms are shown to diffuse on the electrode surface by the random walk motion and thus very strongly affected by low temperature and adsorbates.
The assumed origin of the irreversible loss of SERS intensity as due to the surface adatomic diffusion was confirmed by the observation of SERS of water molecules at low electrolytic concentration of KCl 0.1M solution at the condition of low temperature and long wavelength excitation.
