1D Hydrogen Bond Chain on Pt(211) Stepped Surface Observed by O K-NEXAFS Spectroscopy

1D hydrogen bond chains of D2O molecules formed on a Pt(211) stepped surface are observed by polarization dependent near O K-edge X-ray absorption fine structure spectroscopy (O K-NEXAFS). The 1s -> sigma*(OD) resonance at 535.0 eV in the normal incidence O K-NEXAFS spectrum corresponds to the free OD bond oriented perpendicularly to the step lines, and the resonance at 540.0 eV is related to the hydrogen bond extended in a zigzag manner parallel to the step lines. A structural model consistent with these observations is obtained from the DFT optimization, in which all of the molecules act as one hydrogen donor and acceptor in the 1D chain.