Supplementary materials

Data of TPD; optimized structures of the water chains at the step; discussion of the predicted vibrational frequency; optimized monolayer structures of water; analysis of the optimized structures of water monolayer; Population analysis; optimized structures of hydroxyl and water; structures of water monolayer with hydroxyls; predictions of \ch from the DFT optimized structures; area analysis of the experimental spectra; structural analysis of water monolayer with hydroxyls.