Adsorption of hydrogen on a Pt(111) surface

Step effects and coverage dependence of hydrogen atom diffusion onPt(111)surfaces

“…The difference is that they have set * = 0 in addition to the experimentally obtained different diffusion activation energies. Our results are consistent with the TDS and contact potential measurements, 12,15 from which the coverage dependent desorption energy leads to an estimate of -d * ( d * is the H-H interaction energy at the saddle point for desorption) to be in the range from 15 to 25 meV.…”

“…In the present study, D was measured as a function of substrate temperature over a range 90-150 K. In our experiment, the Pt͑111͒ surface was first dosed with H 2 gas at ϳ100 K to the desired coverage by backfilling the chamber through a leak valve. For a flat Pt͑111͒ sample, coverage was controlled by exposure whose corresponding coverage H was evaluated from the thermal desorption spectra (TDS), 12,13 with the absolute calibration performed at 1 ML. For stepped Pt͑111͒ samples, coverage was set to 0.4 ML by dosing the same amount of H 2 gas as that on flat Pt͑111͒ surface.…”

“…The activation energy values range about 5%-8% of the H-Pt interaction energy (ϳ2.5 eV), 12 typical for gas adsorbate diffusion on metal surfaces. 45 As shown in Fig.…”

“…The interaction of hydrogen with transition metal surfaces, in particular, platinum, has received extensive experimental [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and theoretical [18][19][20][21][22][23][24][25][26][27][28] attention, primarily because platinum is an important heterogeneous catalyst in the hydrogenation reactions, and the hydrogen atom is the simplest chemisorption species which provides the ideal model system for testing the theoretical models and dynamical concepts. Hydrogen is also interesting due to its small mass that opens the possibility of observation of crossover from classical dynamics to quantum dynamics.…”

Energetics and Vibrational States for Hydrogen on Pt(111)

“…Our results convincingly demonstrate the need to go beyond the local harmonic oscillator picture to understand the dynamics of this system. Hydrogen on metal surfaces, and in particular on Pt(111), has received considerable experimental [1][2][3][4][5][6][7] and theoretical [8][9][10][11][12][13][14][15] attention. Together with Pd, Pt is the most important material for heterogeneous catalysis of hydrogenation reactions.…”