Properties of Cu films on Pt(111) revealed by AES, LEED, and DEPES

Calorimetric measurement of adsorption and adhesion energies of Cu on Pt(111)

“…Paffett et al [23] new Cu (1x1) LEED spots at ~1.6 ML, indicating layer 2 in the Cu islands already has a lattice parameter very close to that of Cu(111). Nowicki et al, [24] who grew their films at 330K, did not see the ideal Cu(111) spacing until 5 ML Cu so it unlikely the films are perfectly ordered here, but the lattice strain is relaxed enough to not affect the heat of adsorption.…”

“…Since the growth Cu overlayers on Pt(111) have been extensively described in the literature [22][23][24][25] and summarized above, we use these results to analyze the shape of our heat curves in Figures 1 and 2. STM by Allison et al [22] has shown that Cu grows as pseudomorphic 2D islands in the first monolayer, which nucleate at Pt step edges and then grow outward from the step edges onto terraces in a tendril pattern via step flow growth.…”

“…[23,25] By the second Cu layer, new LEED spots were observed with an ~8% smaller lattice parameter indicating Cu grew with the ideal Cu(111) lattice spacing in the second and subsequent layers. [23] Nowicki et al [24] found using LEED and directional elastic peak electron spectroscopy (DEPES) that Cu forms a misfit Cu(13x13) layer on Pt(12x12) at just over 1 ML and 330K, consistent with a lattice parameter very near that of Cu(111). (Note that the Cu coverages in that paper were all reported as ½ of their true values, based on comparison of the Cu/Pt peak ratio in AES to those reported in, [23] where CO and H chemisorptions clearly identified monolayer completion.…”

“…We interpret these adsorption energies in light of previous detailed structural studies of Cu adsorbed on Pt(111). [22][23][24][25] This is only the second bimetallic system adsorption directly measured by SCAC. [26] Adsorption energies of Cu onto other transition metals have been previously been reported using temperature programmed desorption (TPD), [6] but could not be measured for Cu on Pt since annealing causes Cu/Pt to alloy before Cu desorbs.…”

“…[26] Adsorption energies of Cu onto other transition metals have been previously been reported using temperature programmed desorption (TPD), [6] but could not be measured for Cu on Pt since annealing causes Cu/Pt to alloy before Cu desorbs. [27][28][29][30] The growth of vapor-deposited Cu on Pt(111) has been studied in detail by Auger electron spectroscopy (AES), [23][24][25] low energy electron diffraction (LEED), [23][24][25] thermal desorption spectroscopy (TDS) of H 2 and CO, [23,25] and scanning tunneling microcopy (STM). [22] Copper grows layer-by-layer on Pt(111) in the first monolayer (ML) as evidenced by a linear decrease in the saturation coverage of H and CO (by TPD) with Cu coverage to nearly zero in the first ML, as well as a distinct break in the Cu and Pt AES signals at 1 ML.…”