Adsorption dynamics of O2 on Cu(1 0 0): The role of vacancies, steps and adatims in dissociative chemisorption of O2

Oxygen adsorption-induced nanostructures and island formation on Cu{100}: Bridging the gap between the formation of surface confined oxygen chemisorption layer and oxide formation

“…8,58 A recent investigation also revealed that the minority sites such as vacancies provide a nonactivated adsorption channel. 59 In agreement with Fujita et al, 9 we find that upon oxygen adsorption the surface phase of c͑2 ϫ 2͒-O is converted to the ͑2 ͱ 2 ϫ ͱ 2͒R45°-O reconstruction as indicated by the depressions in Fig. 1͑d͒.…”

“…10,11 However, as our recent molecular beam experiments demonstrate, the 0.5 ML phase remains reactive towards O 2 dissociation. 8,59 This suggests that adsorption of O 2 on Cu͑100͒ is only kinetically limited to 0.5 ML coverage and, as the present investigation demonstrates, by increasing the oxygen impingement rate on the surface ͑i.e., oxygen partial pressure͒, new surface structures leading to subsurface oxide formation can be obtained. The onset and growth of oxide on Cu͑100͒ and vicinal surfaces consisting of Cu͑100͒ terraces have been studied extensively by in situ TEM ͑above 423 K͒, [36][37][38][39][40][41][42][43][44][45] and by utilizing combinations of HREELS/XPS, [24][25][26] hyperthermal O 2 molecular beam ͑HOMB͒/XPS, 27,28 NEXAFS, 29 and MBSS.…”

“…8,58,59 Below 0.3 ML coverage ͑1 ML=1 monolayer= 1.53ϫ 10 15 cm −2 ͒, oxygen atoms occupy fourfold hollow sites resulting in nanosized Cu͑100͒-c͑2 ϫ 2͒-O domains. 9 At higher coverage oxygen induces a missingrow-type Cu͑100͒-͑2 ͱ 2 ϫ ͱ 2͒R45°-O reconstruction which is highly stable and, under ultrahigh vacuum conditions, leads to a saturation coverage of oxygen at 0.5 ML.…”

Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides

“…However, the limiting factor for the oxidation of Cu (100) is the dissociation and on-surface diffusion of the oxygen molecule. The dissociation of the oxygen molecule, although almost barrierless on the clean Cu(100) 124 , is blocked by the on-surface oxygen on the reconstructed surface 248 , and requires the diffusion of the oxygen molecule towards either a high-Cu concentration area 153 or vacancies and surface defects 249,250 where the dissociation barrier is lower. Diffusion of O and Cu atoms on the MR reconstructed surface is slow, having barriers of 1.4 eV for oxygen and 2.0 eV for Cu 153 .…”

Initial sticking probability of O2 on Cu(410)

“…The initial stages of oxygen adsorption attracted less attention and were limited so far to Cu(1 1 0) [4,5] and to Cu(1 0 0) [6][7][8], thus neglecting the role of defects and under-coordinated sites. However a very recent study on sputtered Cu(1 0 0) [9] and some investigations on the O/Cu(4 1 0) system were performed. Cu(4 1 0) is the energetically most stable geometry since it corresponds to the stable faceting observed on Cu upon O 2 exposure [10]; Cu(6 1 0), e.g., reorders forming (4 1 0) facets and its step rises coalesce to produce smaller (4 0 1) facets; the process is complete after exposure to 1000 L of O 2 at room temperature (RT) and subsequent annealing to 520-550 K but, due to the high reactivity of Cu, the first effects are present already after 2 L [11].…”