Proton Configuration in Water Chain on Pt(533)
Naoki Nagatsuka1, Noboru Shibata1, Toya Muratani1
1Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
The Journal of Physical Chemistry Letters
|August 12, 2022
Summary
This study reveals water molecules on platinum form H-down configurations, forming zigzag chains at step sites. This resolves long-standing debates on water
Area of Science:
- Surface Science
- Physical Chemistry
- Spectroscopy
Background:
- Understanding water's interfacial behavior is crucial for catalysis and materials science.
- Previous studies on water at step sites of platinum surfaces yielded conflicting results regarding molecular orientation.
Purpose of the Study:
- To elucidate the wetting behavior and molecular orientation of water on a Pt(533) surface.
- To resolve the controversy surrounding the proton configuration in one-dimensional water chains at step edges.
Main Methods:
- Utilized heterodyne-detected vibrational sum-frequency generation (HD-VSFG) spectroscopy.
- Performed experiments under ultrahigh-vacuum conditions at 145 K.
- Analyzed the imaginary parts of the surface nonlinear susceptibility (Imχ(2)) in the H-bonded OH stretching region.
Main Results:
- Successfully obtained Imχ(2) spectra for submonolayer water coverage.
- Observed negative bands indicating H-down (proton pointing towards the substrate) configurations for water at both step and terrace sites.
- Data on signal growth with coverage and isotopic dilution supported a "zigzag" chain model at the step with H-down orientations.
Conclusions:
- The study confirms H-down configurations for water molecules at step and terrace sites of Pt(533).
- A "zigzag" chain model for water at step edges, incorporating H-down orientations, is proposed and validated.
- This research resolves the debate on proton configuration within 1D water chains at platinum step sites.
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