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Ren, Daxing; Sung, Dougyoung; Gellman, Andrew J.

doi:10.1023/a:1009062407977

Cited by 7 publications

(5 citation statements)

References 23 publications

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“…These studies provided evidence that in the cases of TBP and TCP the film formation takes place following breakage of the C-O bond for the alkyl class and via P-O bond scission in the case of the aryl class. Although studies with alkyl and aryl phosphites have been undertaken [26,27], to our knowledge no data are available on the corresponding sulfur-containing compounds. Some workers have studied the tribological properties of thiophosphate lubricant additives and the films formed by their reaction on iron surfaces.…”

Section: Introductionmentioning

confidence: 99%

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

et al. 2006

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The surface reactivity of tributyl thiophosphate on iron surfaces has been studied in situ by attenuated total reflection Fouriertransform infrared spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed reaction and desorption spectroscopies. The results show that at temperatures lower than 373 K the molecule forms a physisorbed layer on the iron substrate. At 373 K a reaction takes place with the formation of an organic layer, together with iron polyphosphate and sulfate. At higher temperatures temperature-programmed desorption results suggest that the mechanism involves P-O bond scission to yield butoxy groups. This could be preceded by P=S bond scission to give tributyl phosphite, which then, in turn, undergoes P-O bond scission to produce butoxy groups. The results obtained following tribological testing are in agreement with those of thermal tests: evidence of polyphosphate and sulfate formation is found.

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Section: Introductionmentioning

confidence: 99%

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

et al. 2006

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“…Organometallic adsorbates are the subject of widespread interest in surface science, because of their molecular complexity, ease of preparation and deposition, and accessibility to theoretical methods as tractable models to study extended metallic systems. In addition, the relative ease with which organometallic species can undergo decomposition to produce metallic deposits on surfaces via thermal processing, − photolysis, − and interaction with electron beams ,, makes them versatile precursors for surface modifications. There is widespread interest in understanding (i) the structure of thin films composed of organometallic species, (ii) how these structures are influenced by the deposition substrate, and (iii) how the film structure can influence the decomposition behavior of the components.…”

Section: Introductionmentioning

confidence: 99%

Fe(CO)₅ Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: I. Structure

2005

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The adsorption of Fe(CO)(5) onto Au(111)/mica and C(4), C(8), C(12), and C(16) SAMs/Au(111)/mica surfaces has been studied using infrared spectroscopy to elucidate the coverage-dependent structures of these films and the intermolecular couplings that determine the form of the spectra. For all substrates, the first layer is composed of molecules physisorbed with one axial and two equatorial carbonyl groups directed toward the substrate; subsequent layers are preferentially oriented with the C(3) molecular axis aligned perpendicular to the substrate (i.e., one axial carbonyl group directed toward the substrate). The axial vibrational band systematically shifts to higher frequencies with increasing surface coverage because of the effects of intermolecular coupling of the quasiparallel transition dipole moments. The strong effects of dipolar coupling are also witnessed by the trends of the band positions when the distance to the image plane is systematically varied using highly organized self-assembled organic substrates; no band shifts are observed when dilute Fe(CO)(5) is embedded in Xe matrixes under identical experimental conditions. The as-deposited films are structurally stable below 125 K on Au(111)/mica surfaces and below 100 K on the organic self-assembled monolayers. The instability of the films above these temperatures demonstrates that the as-adsorbed films do not form thermodynamically well-defined phases but are structurally metastable. The results presented herein and in the companion paper provide a consistent framework to interpret the spectroscopy of these systems that resolves outstanding issues concerning these films and provides a structural model that explains the dynamic properties of these films during exposure to low-energy electron beams.

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“…Physisorbed molecular films are widely used as model systems to understand fundamental molecule−surface chemistry, to study interphase phenomena in systems of reduced dimension and dimensionality, and to explore the interplay between molecule−surface and molecule−molecule interactions. − In practice, they can also provide valuable insight into diverse applications such as lubricating films − and reactive precursor films. ,, The structural characteristics of these films, the mechanisms of thin-film growth, and the phase diagrams for these systems provide information that is required to optimize the adhesive properties of films, to ensure uniform “wetting” of the substrate, and to rationally design the film constituents for a given application. We are currently interested in using thin adsorbed films of metal−carbonyls [e.g., Fe(CO) 5 , Ni(CO) 4 ] as precursors for electron-induced metallization processes; the precursor materials of interest are principally organometallics, because of the experimental ease with which these target species can be vapor-deposited, − and subsequently dissociated using electron beams. ,,, The structural properties of these as-deposited multilayer films have important consequences for the success of this strategy, and the determination of the film properties using nondestructive probes has become increasingly important in this regard.…”

Section: Introductionmentioning

confidence: 99%

Fe(CO)₅Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: II. Thermal Transformations

2005

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The thermal transformations of as-deposited Fe(CO)(5) films adsorbed on Au(111)/mica and C(4), C(8), C(12), and C(16) self-assembled methyl-terminated monolayer organic surfaces have been studied using infrared spectroscopy to probe how the physical restructuring influences the sensitivity of these systems to low-energy electron beams. A companion publication shows that the as-deposited monolayers are composed of molecules physisorbed with one axial and two equatorial carbonyl groups directed toward the substrate; subsequent layers are preferentially oriented with the C(3) molecular axis aligned perpendicular to the substrate (i.e., one axial carbonyl group directed toward the substrate). In this work, we show that the as-deposited films are structurally unstable above 125 K on Au(111)/mica surfaces and above 100 K on the organic self-assembled monolayers. Above these thresholds, the layered structures transform into three-dimensional aggregates, implying strongly nonwetting behavior for Fe(CO)(5) on each of these substrates; molecular desorption from this aggregate structure takes place between 140 and 160 K. The irreversibility of this temperature-induced transformation demonstrates that the as-deposited layered films do not represent a thermodynamically well-defined phase; this key feature of the as-deposited films is believed to be the cause of the discrepancies in previous attempts to understand Fe(CO)(5)/surface structures based on infrared results. Moreover, the thermally induced transformation to 3D aggregate structures is shown to decrease the apparent sensitivity of the adsorbed Fe(CO)(5) to low-energy electron-induced decarbonylation (0-10 eV) by over 3 orders of magnitude.

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Untitled

Cited by 7 publications

References 23 publications

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

Fe(CO)₅ Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: I. Structure

Fe(CO)₅Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: II. Thermal Transformations

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Untitled

Cited by 7 publications

References 23 publications

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

Fe(CO)5 Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: I. Structure

Fe(CO)5Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: II. Thermal Transformations

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Fe(CO)₅ Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: I. Structure

Fe(CO)₅Thin Films Adsorbed on Au(111) and on Self-Assembled Organic Monolayers: II. Thermal Transformations