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1.
Adsorbed H 2S decomposes on Ni(110) to form primarily surface S and H for coverages of less than 0.5 ML. The hydrogen evolves in two separate TPD peaks, characteristic of hydrogen recombination and desorption from the clean surface and from regions perturbed by chemisorbed sulfur. XPS and HREELS indicate the presence of SH and possibly H 2S groups on the surface at 110 K. The XPS data indicates that for coverages less than about 0.5 ML, the concentration of molecular H 2S is small, but it is difficult to asess the coverage of SH groups. However, all of the molecular species decompose prior to hydrogen desorption (for high coverage, 180 K). Physisorbed H 2S is observed on the surface for coverages greater than about 0.5 ML. The sulfur Auger lineshape was observed to be a function of both coverage and temperature. The changes in the lineshape were attributed to perturbations in local bonding interactions between the S and the Ni surface, perhaps involving some change in either bonding sites or distances but not involving SH bond scission. The decomposition reaction was modeled using a bond order conservation method which successfully reproduced the experimental results. 相似文献
2.
The adsorption and decomposition of H 2S on the Ge(100) surface is investigated. H 2S is a simple sulfur containing molecule that eventually decomposes to yield hydrogen gas and deposits sulfur on the germanium surface. The surface reactions of H 2S are investigated by ultraviolet photoelectron spectroscopy, Auger electron spectroscopy, and temperature programmed desorption. Room temperature exposure of H 2S to Ge(100) results in dissociative adsorption which can be followed easily by ultraviolet photoelectron spectroscopy. Warming the H 2S exposed surface results in some molecular desorption and further decomposition of the adsorbed species. At saturation, 0.25 ML of H 2S decomposes generating 0.5 ML of atomic hydrogen. Above the hydrogen desorption temperature some etching of the germanium surface is observed by sulfur. The etch product, GeS, is subsequently observed in temperature programmed desorption experiments. Exposure of H 2S to the Ge surface at elevated temperatures leads to higher sulfur coverages. A sulfur coverage approaching 0.5 ML can be deposited at the higher exposure temperatures. 相似文献
3.
The effect of adsorbate coverage, adsorption sequence and temperature on the structure, composition and reactivity of coadsorbed layers, produced by dissociative adsorption of O 2 and H 2 at 200 K on a Rh(100) surface, has been studied by combined TPD, XPS and LEED measurements. The emphasis is on the impact of the structure and composition of the mixed O + H layers on the synthesis of hydroxyl and water as a result of the O + H surface reaction. The difference in the O 1s binding energies of adsorbed O (529.9 eV) and OH species (530.8 eV) was used as a fingerprint to monitor the formation of the OH species. The H 2O TPD spectra show substantial variations of the desorption temperature range and the amount of water evolved with coadsorbate coverage and structure: from 270 to 350 K and from 0 to 0.08 ML, respectively. It has been found that dense O + H adlayers, where the O coverage is in the range 0.25-0.4 ML, favor the formation of stable OH species. The maximum amount of stable hydroxyl OH species ( 0.16 ML) can be produced by heating of these dense adlayers to 260 K. This results in reordering of the adspecies to form a new O + OH − (2 × 6) structure, where hydroxyls react readily to evolve 0.08 ML of water in a sharp desorption peak at 280 K. The effect of the adlayer density and restructuring on the production of OH and H 2O is discussed. 相似文献
4.
Propylene oxidation was studied on the Pt(111) surface over a wide range of reaction stoichiometries using temperature programmed methods. Reaction of propylene with excess oxygen results in complete oxidation to water and carbon dioxide, with oxydehydrogenation to form water beginning at 290 K. The initiation of skeletal oxidation occurs after water formation begins, except for the highest propylene coverages. A stable dehydrogenated intermediate with a C 3H 5 stoichiometry is formed in the 300 K temperature range during oxidation. Reaction of propylene with substoichiometric amounts of oxygen results in incomplete oxidation with hydrocarbon decomposition dominating after depletion of surface oxygen. Increasing oxygen coverage results in more complete oxidation. Oxidation processes result in water, carbon dioxide, and carbon monoxide, while decomposition results in hydrogen, propylene, and propane desorption with some surface carbon remaining. Propylene- d6 and selectively labeled propylene-3,3,3- d3 (CH 2CHCD 3) experiments indicated initial water formation results from oxydehydrogenation of one of the olefinic hydrogens. At the highest propylene and oxygen coverages studied, we observed small amounts of partial oxidation which indicate that the vinyl hydrogen is removed initially, resulting in the formation of an adsorbed H 2CCCH 3 intermediate. The partial oxidation products observed are acetone desorbing at 200 K and acetic acid at 320 K. Removal of the first skeletal carbon begins at 320 K, except for the highest propylene coverages. Preadsorption of molecular oxygen limits adsorption of propylene and preadsorption of propylene limits molecular oxygen adsorption at 110 K. Similar oxidation mechanisms are observed following initial adsorption of both molecular and atomic oxygen, which is expected since molecular oxygen dissociates and/or desorbs well below oxidation temperatures. 相似文献
5.
The reaction of CO 2 and H 2O to form bicarbonate (HCO −3) was examined on the nearly perfect and vacuum annealed surfaces of TiO 2(110) with temperature programmed desorption (TPD), static secondary ion mass spectrometry (SSIMS) and high resolution electron energy loss spectrometry (HREELS). The vacuum annealed TiO 2(110) surface possesses oxygen vacancy sites that are manifested in electronic EELS by a loss feature at 0.75 V. These oxygen vacancy sites bind CO 2 only slightly more strongly (TPD peak at 166 K) than do the five-coordinated Ti 4+ sites (TPD peak at 137 K) typical of the nearly perfect TiO 2(110) surface. Vibrational HREELS indicates that CO 2 is linearly bound at the latter sites with a νa(OCO) frequency similar to the gas phase value. In contrast, oxygen vacancies dissociate H 2O to bridging OH groups which recombine to liberate H 2O in TPD at 490 K. No evidence for a reaction between CO 2 and H 2O is detected on the nearly perfect surface. In sequentially dosed experiments on the vacuum annealed surface at 110 K, CO 2 adsorption is blocked by the presence of preadsorbed H 2O, adsorbed CO 2 is displaced by postdosed H 2O, and there is little or no evidence for bicarbonate formation in either case. However, when CO 2 and H 2O are simultaneously dosed, a new CO 2 TPD state is observed at 213 K, and the 166 K state associated with CO 2 at the vacancies is absent. SSIMS was used to tentatively assign the 213 K CO 2 TPD state to a bicarbonate species. The 213 K CO 2 TPD state is not formed if the vacancy sites are filled with OH groups prior to simultaneous CO 2+H 2O exposure. Sticking coefficient measurements suggest that CO 2 adsorption at 110 K is precursor-mediated, as is known to be the case for H 2O adsorption on TiO 2(110). A model explaining the circumstances under which the proposed bicarbonate species is formed involves the surface catalyzed conversion of a precursor-bound H 2O–CO 2 van der Waals complex to carbonic acid, which then reacts at unoccupied oxygen vacancies to generate bicarbonate, but falls apart to CO 2 and H 2O in the absence of these sites. This model is consistent with the conditions under which bicarbonate is formed on powdered TiO 2, and is similar to the mechanism by which water catalyzes carbonic acid formation in aqueous solution. 相似文献
6.
The co-adsorption of oxygen and deuterium at 100 K on a Pd(110) surface has been studied by measurements of the change in work function (Δφ) and by thermal desorption spectroscopy (TDS). When the surface with co-adsorbed species is heated, the adsorbates O and D react to form D 2O which desorbs from the surface at T > 200 K. The D 2O desorption peaks shift continuously to lower temperatures as the surface D coverage (θ D) increases. The maximum production of D 2O is estimated to be 0.26 ML (1 ML = 9.5 × 10 14 atoms cm −2), resulting from reaction in a layer containing 0.65 ML D and 0.3 ML O. The maximum work function increase caused by adsorption of D to saturation onto oxygen precovered Pd(110) decreases almost linearly with Δφ O of the oxygen precovered surface. On a surface with pre-adsorbed D however, the maximum Δφ increase contributed by oxygen adsorption decreases abruptly at Δφ D > 200 mV. This sharp change occurs at θ D > 1 ML and is believed to be associated with the development of the reconstructed (1 × 2) phase of D/Pd(110). 相似文献
7.
The oxidation of hydrazine on the clean Pt(111) surface has been investigated by temperature-programmed reaction spectroscopy (TPRS) in the temperature range 130–800 K. Direct reaction of molecular oxygen is observed on the Pt(111) surface for the first time, as indicated by the desorption of nitrogen beginning at 130 K with a maximum rate at 145 K, below the molecular oxygen dissociation temperature. Direct reaction of hydrazine with adsorbed molecular oxygen results in the formation of water and nitrogen. With excess hydrazine, all surface oxygen is reacted, forming water. When only adsorbed atomic oxygen is present, the low-temperature nitrogen yield decreases by a factor of 3 and the peak nitrogen desorption temperature increases to 170 K. No high-temperature (450–650 K) nitrogen desorption characteristic of nitrogen atom recombination is seen, indicating that during oxidation the nitrogen-nitrogen bond in hydrazine remains intact, as observed previously for hydrazine decomposition on the Pt(111) surface and hydrazine oxidation on rhodium. Two water desorption peaks are observed, characteristic of desorption-limited (175 K) and reaction-limited (200 K) water evolution from the Pt(111) surface. For low coverages of hydrazine, only the reaction-limited water desorption is observed, previously attributed to water formed from adsorbed hydroxyl groups. When excess hydrazine is adsorbed, the usual hydrazine decomposition products, H 2, N 2 and NH 3, are also observed. No nitrogen oxide species (NO, NO 2 and N 2O) were observed in these experiments, even when excess oxygen was available on the surface. 相似文献
8.
The adsorption and desorption of in situ deposited glycine on Pt(111) were investigated with thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). Glycine adsorbs intact on Pt(111) at all coverages at temperatures below 250 K. The collected results suggest that the glycine molecules adsorb predominantly in the zwitterionic state both in the first monolayer and in multilayers. Upon heating, intact molecules start to desorb from multilayers around 325 K. The second (and possibly third) layer(s) are somewhat more strongly bound than the subsequent layers. The multilayer desorption follows zero order kinetics with an activation energy of 0.87 eV molecule −1. From the first saturated monolayer approximately half of the molecules desorbs intact with a desorption peak at 360 K, while the other half dissociates before desorption. Below 0.25 monolayer all molecules dissociate upon heating. The dissociation reactions lead to H 2, CO 2, and H 2O desorption around 375 K and CO desorption around 450 K. This is well below the reported gas phase decomposition temperature of glycine, but well above the thermal desorption temperatures of the individual H 2, CO 2, and H 2O species on Pt(111), i.e. the dissociation is catalyzed by the surface and H 2, CO 2, and H 2O immediately desorb upon dissociation. For temperatures above 500 K the remaining residues of the dissociated molecules undergo a series of reactions leading to desorption of, for example, H 2CN, N 2 and C 2N 2, leaving only carbon left on the surface at 900 K. Comparison with previously reported studies of this system show substantial agreement but also distinct differences. 相似文献
9.
Atomic oxygen coverages of up to 1.2 ML may be cleanly adsorbed on the Au(111) surface by exposure to O 3 at 300 K. We have studied the adsorbed oxygen layer by AES, XPS, HREELS, LEED, work function measurements and TPD. A plot of the O(519 eV)/Au(239 eV) AES ratio versus coverage is nearly linear, but a small change in slope occurs at ΘO=0.9 ML. LEED observations show no ordered superlattice for the oxygen overlayer for any coverage studied. One-dimensional ordering of the adlayer occurs at low coverages, and disordering of the substrate occurs at higher coverages. Adsorption of 1.0 ML of oxygen on Au(111) increases the work function by +0.80 eV, indicating electron transfer from the Au substrate into an oxygen adlayer. The O(1s) peak in XPS has a binding energy of 530.1 eV, showing only a small (0.3 eV) shift to a higher binding energy with increasing oxygen coverage. No shift was detected for the Au 4f 7/2 peak due to adsorption. All oxygen is removed by thermal desorption of O 2 to leave a clean Au(111) surface after heating to 600 K. TPD spectra initially show an O 2 desorption peak at 520 K at low ΘO, and the peak shifts to higher temperatures for increasing oxygen coverages up to ΘO=0.22 ML. Above this coverage, the peak shifts very slightly to higher temperatures, resulting in a peak at 550 K at ΘO=1.2 ML. Analysis of the TPD data indicates that the desorption of O 2 from Au(111) can be described by first-order kinetics with an activation energy for O 2 desorption of 30 kcal mol −1 near saturation coverage. We estimate a value for the Au–O bond dissociation energy D(Au–O) to be 56 kcal mol −1. 相似文献
10.
Thermal desorption of phosphorus on Si(100) surfaces has been investigated by varying the phosphorus coverage from zero to one monolayer (ML). The reaction path of phosphorus desorption is complicated and strongly dependent upon the phosphorus coverage. In the thermal desorption spectra, there are three apparent desorption peaks at 750, 850 and 1000°C. The entire phosphorus atoms on the surface desorb as P 2 through recombinative reactions irrespective of the desorption temperature and the coverage. In the lower coverages below 0.2 ML, the thermal desorption spectra are characterized by a single peak at 900°C which is considered to be the desorption from Si---P heterodimers. At higher coverages exceeding 0.2 ML, it is considered that three desorption schemes from P---P, Si---P dimers and defects coexist in the reaction stage. 相似文献
11.
The decomposition reactions of formaldehyde on clean and oxygen dosed Pt(110) have been studied by LEED, XPS and TPRS. Formaldehyde is adsorbed in two states, a monolayer phase and a multilayer phase which were distinguishable by both TPRS and XPS. The saturated monolayer (corresponding to 8.06 × 10 14 molecules cm −2) desorbed at 134 K and the multilayer phase (which could not be saturated) desorbed at 112 K. The only other reaction products observed at higher temperatures were CO and H 2 produced in desorption limited processes and these reached a maximum upon saturation of the formaldehyde monolayer. The desorption spectrum of hydrogen was found to be perturbed by the presence of CO as reported by Weinberg and coworkers. It is proposed that local lifting of the clean surface (1 × 2) reconstruction is responsible for this behaviour. Analysis of the TPRS and XPS peak areas demonstrated that on the clean surface approximately 50% of the adsorbed monolayer dissociated with the remainder desorbing intact. Reaction of formaldehyde with preadsorbed oxygen resulted in the formation of H 2O (hydroxyl recombination) and CO 2 (decomposition of formate) desorbing at 200 and 262 K, respectively. The CO and H 2 desorption peaks were both smaller relative to formaldehyde decomposition on the clean surface and in particular, H 2 desorbed in a reaction limited process associated with decomposition of the formate species. No evidence was found for methane or hydrocarbon evolution in the present study under any circumstances. The results of this investigation are discussed in the light of our earlier work on the decomposition of methanol on the same platinum surface. 相似文献
12.
The purpose of this review is to compare and discuss recent experimental and theoretical results in the field of H 2O-solid interactions. We emphasize studies of low (submonolayer) coverages of water on well-characterized, single-crystal surfaces of metals, semiconductors and oxides. We discuss the factors which influence dissociative versus associative adsorption pathways. When H 2O adsorbs molecularly, it tends to form three-dimensional hydrogen-bonded clusters, even at fractional monolayer coverages, because the strength of the attractive interaction between two molecules is comparable to that of the substrate-H 2O bond. The template effect of the substrate is important in determining both the local orientation and long-range order of H 2O molecules in these clusters. The influence of surface additive atoms (e.g., O, Br, Na, K) and also surface imperfections (e.g. steps and defects) on the surface structure and chemistry of H 2O is examined in detail. Some results on single-crystal substrates are compared with earlier measurements of H 2O adsorption on high-area materials. 相似文献
13.
The adsorption and reaction of methyl nitrite (CH 3ONO, CD 3ONO) on Pt(111) was studied using HREELS, UPS, TPD, AES, and LEED. Adsorption of methyl nitrite on Pt(111) at 105 K forms a chemisorbed monolayer with a coverage of 0.25 ML, a physisorbed second layer with the same coverage that desorbs at 134 K, and a condensed multilayer that desorbs at 117 K. The Pt(111) surface is very reactive towards chemisorbed methyl nitrite; adsorption in the monolayer is completely irreversible. CH 3ONO dissociates to form NO and an intermediate which subsequently decomposes to yield CO and H 2 at low coverages and methanol for CH 3ONO coverages above one-half monolayer. We propose that a methoxy intermediate is formed. At least some C–O bond breaking occurs during decomposition to leave carbon on the surface after TPD. UPS and HREELS show that some methyl nitrite decomposition occurs below 110 K and all of the methyl nitrite in the monolayer is decomposed by 165 K. Intermediates from methyl nitrite decomposition are also relatively unstable on the Pt(111) surface since coadsorbed NO, CO and H are formed below 225 K. 相似文献
14.
At 300 K oxygen chemisorbs on Ag(331) with a low sticking probability, and the surface eventually facets to form a (110)?(2 × 1) O structure with ΔΦ = +0.7 eV. This facetting is completely reversible upon O 2 desorption at ~570 K. The electron impact properties of the adlayer, together with the LEED and desorption data, suggest that the transition from the (110) facetted surface to the (331) surface occurs at an oxygen coverage of about two-thirds the saturation value. Chemisorbed oxygen reacts rapidly with gaseous CO at 300 K, the reaction probability per impinging CO molecule being ~0.1. At 300 K chlorine adsorbs via a mobile precursor state and with a sticking probability of unity. The surface saturates to form a (6 × 1) structure with ΔΦ = +1.6 eV. This is interpreted in terms of a buckled close-packed layer of Cl atoms whose interatomic spacing is similar to those for Cl overlayers on Ag(111) and Ag(100). Desorption occurs exclusively as Cl atoms with Ed ~ 213 kJ mol ?1; a comparison of the Auger, ΔΦ, and desorption data suggests that the Cl adlayer undergoes significant depolarisation at high coverages. The interaction of chlorine with the oxygen predosed surface, and the converse oxygen-chlorine reaction are examined. 相似文献
15.
The adsorption of D 2O on Zr(0001) at 80 K and its subsequent reactions at higher temperatures have been studied by thermal desorption spectroscopy (TDS), work-function measurements (Δф), nuclear reaction analysis (NRA), LEED, infrared reflection spectroscopy (FTIR-RAS), Auger electron spectroscopy (AES), and static secondary ion mass spectroscopy (SSIMS). D 2O adsorption on Zr(0001) at 80 K is accompanied by a Δф of −1.33 eV. The adsorbed D 2O can be characterized into three layers by TDS: a chemisorbed layer (up to 0.23 ML), a second adsorbed layer, and an ice layer. The chemisorbed D 2O dissociates into OD ad and D ad at 80 K (possibly also into O ad) and no desorption products could be detected, implying that the reaction products dissolved into the zirconium at temperatures appropriate for each component. The ice layer and most of the second adsorbed layer desorb as molecular water during heating. The water adsorbed at 80 K did not form any long-range ordered structure, but a (2 × 2) LEED pattern that was formed by heating the sample to temperatures above 430 K is believed due to be an ordered oxygen superstructure. 相似文献
16.
The kinetics of H 2 desorption from H/W(110) and H/Fe 1/W(110) were studied by measuring work function changes Δø vs time at a number of temperatures. Combination with previously determined Δø vs coverage data and differentiation at various fixed coverages gave rate vs T data from which activation energies of desorption could be obtained. E vs coverage results agree well with previously determine Δ Hdes results. In the case of H/Fe 1/W(110) this includes a rise from 20 to 30 kcal mol −1 of H 2 at H/Fe = H/W > 0.3. Plots of rate −dθ/d t vs θ (θ being coverage in units of H/W) vary much more steeply than θ 2 at most coverages for both systems. The θ dependence can be explained almost quantitatively in terms of the variations of Δ Hdes and surface entropy Ss with coverage, by assuming that rates of desorption are equal to the equilibrium rates of adsorption. The latter can be formulated thermodynamically, except for a sticking coefficient, s. Values for s(θ, T) can also be obtained and show relatively little temperature dependence. 相似文献
17.
The interaction of HNCO with oxygen dosed Rh(111) surface has been investigated by Auger electron, electron energy loss and thermal desorption spectroscopy. The presence of adsorbed oxygen exerted no apparent influence on the weakly adsorbed HNCO ( Tp = 130 K). It promoted, however, the dissociative adsorption of HNCO by forming a strong O—H bond which prevented the associative desorption of HNCO. As a result no H 2 and NH 3 formation occurred, in contrast with the clean surface, and the surface concentration of irreversibly bonded NCO was also increased. New products of the surface reaction were H 2O and CO 2, in addition to CO and N 2 observed on a clean surface. From the behavior of the losses characteristic for the adsorbed NCO it appeared that the preadsorbed oxygen exerted a significant stabilizing effect on the NCO bonded to the Rh. 相似文献
18.
The oxidation of the adsorbed π-allyl (η 3-C 3H 5), prepared on atomic oxygen- and hydroxyl-covered Ag(110) by dissociation of allyl chloride (C 3H 5Cl), is investigated with temperature-programmed desorption and high-resolution electron energy loss spectroscopy. Allyl chloride adsorbs molecularly on oxygen-covered Ag(110) at 110 K. Upon heating to 180 K, some allyl chloride dissociates to form π-allyl and atomic chlorine, and the remainder desorbs molecularly. The π-allyl undergoes combustion to form hydroxyl or carbonate until all of the free oxygen is consumed by 200 K. Migratory insertion of hydroxyl into excess π-allyl commences near 220 and finishes by 250 K, forming adsorbed allyl alcohol (C 3H 5OH), which reacts either with excess hydroxyl near 240 K to form allyl alkoxy (η 1(O)-C 3H 5O) and water, or with π-allyl at 250 K to form allyl alkoxy and propylene (C 3H 6). Th allyl alkoxy evolves acrolein (C 3H 4O) by β-hydrogen elimination near 285 K, and propylene is evolved concurrently as the hydrogen released by this reaction rapidly scavenges π-allyl. Finally, the remaining π-allyl dimerizes to form 1,5-hexadiene (C 6H 10), which desorbs at 315 K. The gross observations of reaction pathways and temperatures are used to evaluate important aspects of the thermochemistry of these reactions. 相似文献
19.
Adsorption of water at 100 K. on clean and oxygen-covered Cu(110) has been studied using UPS, TDS, Δφ and LEED measurements. The results indicate that two-dimensional hydrogenbonded islands are formed on the clean surface. The long-range order in these islands is in registry with the substrate lattice and gives rise to a c(2×2) LEED pattern. Upon the formation of multilayer ice, the ordering disappears. The presence of oxygen on the surface disrupts the hydrogen bonding, and composite oxygen-water layers are formed. A model of the arrangement of oxygen atoms and water molecules is presented, based upon the LEED observations for these layers and an estimate of the relative oxygen and water coverages. The intensity variation of a thermal desorption peak at 290 K, attributed to adsorbed OH species, with oxygen coverage is in accordance with this model. For low oxygen coverages, the TDS and Δφ results indicate that small oxygen-water clusters with an enhanced ratio of water molecules per adsorbed oxygen atom are present. 相似文献
20.
The surface composition and structure of natural diamond (100) surfaces subsequently oxidized with activated oxygen at Tsub≤35°C were investigated with high-resolution electron energy loss spectroscopy (HREELS), Auger electron spectroscopy, electron loss spectroscopy (ELS) and low-energy electron diffraction (LEED). Complete surface oxidation (oxygen coverage θ=1 ML) required doses of hundreds of kilolangmuirs of O 2. HREELS vibrational spectra permitted identification of the specific surface oxygen species, and also provided information about the diamond surface states. Most surface sites lost their hydrogen at least once before becoming oxidized. The oxygen coverage θ increased quickly at first, and then more slowly as saturation was approached; different mechanisms or sites may have accounted for the decreased rate. The relative distribution of oxygen species varied with the oxidation conditions. Ether, carbonyl and hydroxyl groups appeared during the initial stages of oxidation, but the hydroxyl groups disappeared at higher coverages. Bridge-bonded ether groups dominated at saturation coverage, although smaller amounts of carbonyl and hydroxyl were still observed. The carbonyl and C---H stretch frequencies increased with oxygen dose due to formation of higher oxidation states and/or hydrogen bonding between adjacent groups. ELS revealed only a low concentration of C=C dimers on the oxidized surfaces, and no evidence of graphitization. Surfaces generated by oxygen addition and then desorption were more reactive than surfaces generated by hydrogen desorption. Oxidized surfaces that were heated in vacuum and then rehydrogenated did not recover the sharp LEED patterns and HREELS spectra of the original plasma-smoothed surface. This effect was presumably due to surface roughening caused by oxygen desorption as CO and CO2, and creation of reactive high-energy sites that quickly bonded to available background gases and prevented large areas of organized surface reconstruction. 相似文献
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