Proton transfer in water-hydroxyl mixed overlayers on Pt(1 1 1): Combined approach of laser desorption and spatially-resolved X-ray photoelectron spectroscopy

Masanari Nagasaka, Hiroshi Kondoh, Kenta Amemiya, Toshiaki Ohta, Yasuhiro Iwasawa

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Proton transfer in water-hydroxyl mixed overlayers on a Pt(1 1 1) surface was studied by a combination of laser induced thermal desorption (LITD) method and spatially-resolved X-ray photoelectron spectroscopy (micro-XPS). The modulated pattern OH + H2O/H2O/OH + H2O was initially prepared by the LITD method; vacant area with a 400 μm width was first formed in the mixed OH + H2O overlayer by irradiation of focused laser pulses, and followed by refilling the vacant area with pure H2O. Spatial distribution changes of OH and H2O were measured as a function of time with the micro-XPS technique, which indicated that H2O molecules in the central region flow into the OH + H2O region. From quantitative analyses using a diffusion equation, we found that the proton transfer in the mixed overlayer consists of at least two pathways: direct proton transfer from H2O to OH in the nearest site and the proton transfer to the next-nearest site via H3O+ formation. The time scale of first and second path was estimated to be 5.2 ± 0.9 ns and 48 ± 12 ns at 140 K, respectively. In the presence of water capping layer, however, the rate of proton transfer is reduced by an order of magnitude, which would be explained by peripatetic behavior of proton into H2O capping layer.

Original languageEnglish
Pages (from-to)1690-1695
Number of pages6
JournalSurface Science
Volume603
Issue number10-12
DOIs
Publication statusPublished - 2009 Jun 1

Fingerprint

Proton transfer
Hydroxyl Radical
Desorption
X ray photoelectron spectroscopy
desorption
photoelectron spectroscopy
protons
Water
Lasers
Thermal desorption
water
lasers
x rays
refilling
Spatial distribution
Protons
Laser pulses
Irradiation
spatial distribution
Molecules

Keywords

  • Adsorbed water
  • Laser induced thermal desorption
  • Platinum surface
  • Proton transfer
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

  • Surfaces and Interfaces
  • Condensed Matter Physics
  • Materials Chemistry
  • Surfaces, Coatings and Films

Cite this

Proton transfer in water-hydroxyl mixed overlayers on Pt(1 1 1) : Combined approach of laser desorption and spatially-resolved X-ray photoelectron spectroscopy. / Nagasaka, Masanari; Kondoh, Hiroshi; Amemiya, Kenta; Ohta, Toshiaki; Iwasawa, Yasuhiro.

In: Surface Science, Vol. 603, No. 10-12, 01.06.2009, p. 1690-1695.

Research output: Contribution to journalArticle

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AB - Proton transfer in water-hydroxyl mixed overlayers on a Pt(1 1 1) surface was studied by a combination of laser induced thermal desorption (LITD) method and spatially-resolved X-ray photoelectron spectroscopy (micro-XPS). The modulated pattern OH + H2O/H2O/OH + H2O was initially prepared by the LITD method; vacant area with a 400 μm width was first formed in the mixed OH + H2O overlayer by irradiation of focused laser pulses, and followed by refilling the vacant area with pure H2O. Spatial distribution changes of OH and H2O were measured as a function of time with the micro-XPS technique, which indicated that H2O molecules in the central region flow into the OH + H2O region. From quantitative analyses using a diffusion equation, we found that the proton transfer in the mixed overlayer consists of at least two pathways: direct proton transfer from H2O to OH in the nearest site and the proton transfer to the next-nearest site via H3O+ formation. The time scale of first and second path was estimated to be 5.2 ± 0.9 ns and 48 ± 12 ns at 140 K, respectively. In the presence of water capping layer, however, the rate of proton transfer is reduced by an order of magnitude, which would be explained by peripatetic behavior of proton into H2O capping layer.

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