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Determination of hydrogen surface coverage of Pt0.5Ni0.5 single crystals by NRA

https://doi.org/10.1016/0168-583X(92)95442-TGet rights and content

Abstract

The 1H(15N, αγ)12C resonant nuclear reaction has been used to measure the hydrogen coverage on the (110) and (111) faces of Pt0.5Ni0.5 single crystals. Surface treatments prior to adsorption experiments as well as beam-induced defects have been investigated for ensuring a correct determination of the hydrogen concentration. Hydrogen coverage has been measured from 115 to 400 K in the 10−8-10−4 mbar H2 pressure range. The maximum coverage is one monolayer on the (110) face and 0.2 monolayer on the (111) face. An interpretation for these low values, compared with the coverage of Ni(110) and Pt(111), is proposed. The composition variation of the first three atomic layers of the crystals accounts for this difference.

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Cited by (8)

  • Hydrogen detection near surfaces and shallow interfaces with resonant nuclear reaction analysis

    2014, Surface Science Reports
    Citation Excerpt :

    The latter conclusion was encouraged by the observation that at 270 K the work function remained strongly reduced relative to clean Pt(111), which seemingly suggested that H was still present on or very close below the surface. Mortensen et al., however, combined the NRA D coverage measurement with transmission channeling at thin Pt(111) single crystal films, which definitely ruled out D occupation of octahedral interstitial sites below the Pt(111) surface for the questionable temperature regime (110–300 K) [280]. In addition their channeling data specified the D adsorption position on Pt(111) as the fcc three-fold hollow site at a height of 0.58 Å above the surface and thereby clearly ruled out hcp site occupation that also had been given consideration at the time.

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