Time-evolved transmission spectra illustrating the change in IR background during exposure of atomic hydrogen to Cu(111) at 180 K. Inset: plot of background transmission at 2000 cm−1 (red squares) and integrated absorbance of the 1150 cm−1-band (blue circles) vs. total hydrogen coverage on Cu(111) at 180 K.
Time-evolved IR spectra obtained during the adsorption of atomic hydrogen on Cu(111) at 160 K. Spectra were collected at 40 s time intervals, and the initial period without the peak at 1150 cm−1 has not been included. (Absorbance spectra are baseline corrected.) Inset: extended spectral range from 1500 to 950 cm−1.
Time-evolved IR spectra obtained for the 160 K-surface in Figure 2 during heating from 140 K to 200 K. (Heating rate = 0.1 K/s; 4 K/spectrum.) Inset: integrated IR absorbance as a function of temperature for the 160 K-surface (red squares) and the 180 K-surface (blue circles). (Integration range from 1120 to 1160 cm−1.)
Thermal desorption spectrum (mass 4) after the adsorption of a saturation coverage of deuterium on Cu(111) at 160 K. (Heating rate = 3 K/s). The corresponding IR spectrum is shown in the inset.
(a) CO adsorption on a H-Cu(111) surface during cooling to 105 K (see text for details). (b) CO adsorption after TP-IRRAS to 220 K and during re-cooling to 95 K. (c) CO adsorption after heating to 310 K and re-cooling to 104 K. (a)-(c) PCO = 1 × 10−8 Torr CO.
IR spectra obtained after adsorption of H at 180 K and re-cooling of the surface from 180 K to 110 K. Inset: integrated absorbance as a function of exposure (left) and recooling (right).
Potential energy diagram for the adsorption and absorption of H at high coverage (3 hydrogen atoms per unit cell). The top view of the optimized structures for the 3SH, TS1, 2SH +1SSH-1st, TS2 systems, and the side view of the 2SH+1SSH-2nd system are also shown. SH-surface H, SSH-1st – H between the surface layer and the first sub-surface layer, SSH-2nd – H between the first and the second sub-surface layer (SSH-2nd), TS-transition state. Big brown: Cu; small white: H.
Experimental Ea calculation between SH and SSH-1st sites, from the SH coverage measurements in the inset of Figure 3 .
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