Chemisorption of hydrogen on the missing-row Pt(110)-(1 x 2) surface

Chemisorption of hydrogen on the missing-row reconstructed Pt(110)-(1 x 2) surface has been studied by TPD, quantitative LEED, and DFT calculations. An (atypical) chemisorption site on the outermost close-packed rows with an ideal coverage of 0.5 ML (beta(2)-state) is found. Adsorption sites on the (111) microfacets are occupied only at higher coverage (beta(1)-state). After exposures of more than 400 L, the TPD spectra clearly reveal the controversly discussed alpha-state. In the same coverage range, an intense 1 x 4 superstructure becomes visible at LEED energies around 50 eV. The saturation coverage for chemisorption at T = 120 K is 33% higher than assumed previously.