Adsorption and Polymerization of Thiophene on a Ag(111) Surface

Baumgärtner, K.‐M.; Volmer‐Uebing, M.; Taborski, J.; Bäuerle, Peter; Umbach, E.

doi:10.1002/bbpc.19910951134

Cited by 53 publications

(29 citation statements)

References 24 publications

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“…This finding is corroborated by the above-mentioned absence of XPS core level shift differences between the C and S atoms when EC4T multilayer and monolayer molecules are compared. 15,16 The Ag-S bond distance is, however, smaller than the sum of the Ag and S van der Waals radii, which is 3.5 Å ͓1.7 ϩ1.8 Å ͑Ref. 32͔͒ and is also still slightly smaller ͑at least for the atoms a and d͒ than the sum of the atomic radius of Ag metal ͑1.45 Å͒ plus the S van der Waals radius, i.e., 3.25 Å.…”

Section: Discussionmentioning

confidence: 97%

“…Upon annealing of the commensurate EC4T monolayer, no desorption, but dissociation of the EC4T occurs. 12 The comparison of x-ray photoemission spectroscopy ͑XPS͒ data ͑C 1s and S 2p͒ of the EC4T monolayer and multilayer shows only very small overall shifts of 0.3 eV, as found for physisorbed monothiophene 16 and bithiophene on Ag͑111͒. 17 This reveals that no local bonding of the S atoms to the surface via the lone pair occurs, as for instance, found for monothiophene on more reactive substrates.…”

Section: Introductionmentioning

confidence: 84%

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Adsorption site determination of a large π-conjugated molecule by normal incidence x-ray standing waves: End-capped quaterthiophene on Ag(111)

et al. 2002

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Using normal incidence x-ray standing waves, we determined the geometric structure of the adsorption site of a large -conjugated molecule with six rings, end-capped quaterthiophene ͑EC4T͒, on the Ag͑111͒ surface in the commensurate monolayer. The S 1s absorption profiles were measured for the ͑111͒ and (1 11) Bragg reflections. The vertical coherent position D co (111) , i.e., the average distance between molecules and Ag surface, was determined to 3.15Ϯ0.05 Å. This is less than expected for van der Waals bonding and more than known for a local S-Ag bond, thus revealing that the surface bonding involves the entire conjugated system, in agreement with earlier photoemission results. The lateral position of the EC4T molecule was obtained from a simulation of the experimental coherent position in ͓1 11͔ direction (1.02Ϯ0.1 Å). This results in the first complete determination of the adsorption geometry of a large flat-lying organic molecule on an inorganic surface.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 84%

Adsorption site determination of a large π-conjugated molecule by normal incidence x-ray standing waves: End-capped quaterthiophene on Ag(111)

et al. 2002

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“…[16][17][18][19][20][21]26 For comparison with such work, measurements were performed on thiophene films after exposing them to electrons of energies Ͼ50 eV, for extended periods. [16][17][18][19][20][21]26 For comparison with such work, measurements were performed on thiophene films after exposing them to electrons of energies Ͼ50 eV, for extended periods.…”

Section: B Esd Of Negative Ions From Electron Irradiated Thiophene Filmmentioning

confidence: 99%

Electron stimulated desorption of anionic fragments from films of pure and electron-irradiated thiophene

Hedhili

Cloutier

Bass

et al. 2006

The Journal of Chemical Physics

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The electron stimulated desorption (ESD) of anions is used to explore the effects of electron irradiation on a thiophene film and we report measurements for electron impact on multilayer thiophene condensed on a polycrystalline platinum substrate. Below 22 eV and at low electron dose, desorbed anions include H- (the dominant signal) as well as S-, CH2-, SH- and SCH2-. Yield functions show that anions are desorbed both by dissociative electron attachment (DEA) with resonances observed at 9.5, 11, and 16 eV, and for energies >13 eV, by dipolar dissociation (DD). An increase in the S- signal from electron irradiated (beam-damaged) thiophene films and the appearance of a new DEA resonance in the S- yield function at 6 eV are linked to rupture of the thiophene ring and the formation of sulfur-terminated products within the film. The threshold energy for ring rupture is 5 eV. The desorption of new anions such as C4H3S- (Thiophene-H)- is also observed from electron irradiated films and these likely arise from the decomposition of large radiation product molecules synthesized in the film. The yield functions of H-, S-, SH-, (Thiophene-H)-, and (Thiophene+H)- anions from irradiated thiophene films that have been annealed to 300 K, each exhibit a single resonant feature centered around 5.1 eV, suggesting that all signals derive from DEA to the same molecular radiation product. In contrast, only H- and S- are observed to desorb from films of 2-2-bithiophene and no resonance is seen below approximately 10 eV in the anion yield functions. These data suggest that electron irradiation causes formation of ring-opened oligomers, and that closed-ring or 'classical" oligomers, (similar to bithiophene) if formed, contribute little to the ESD of anions.

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“…12 After exposure of multilayer films to Mg KR radiation, the photoelectron spectrum showed a shift in the C 1s and S 2p peaks, indicating a change in the chemical environment for carbon and sulfur. In postirradiation temperature-programmed desorption (TPD), oligomers of up to four units were identified.…”

Section: Introductionmentioning

confidence: 99%

RAIRS and TPD Study of the Direct Photopolymerization of Styrene Thin Films in Ultrahigh Vacuum

Carlo

Grassian

1997

Langmuir

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Photoinduced polymerization of styrene monomer thin films condensed on a Ag(110) substrate has been studied using a combination of reflectance absorption infrared spectroscopy (RAIRS) and temperatureprogrammed desorption (TPD). At 100 K, styrene polymerizes upon ultraviolet irradiation. Postirradiation TPD indicates that several species form in the film. These species are identified as styrene dimer, trimer, and tetramer. RAIR spectra as a function of temperature provide evidence for the formation of polystyrene as well. A mechanism for the direct UV photopolymerization of styrene thin films is proposed. IntroductionRecently, there have been reports in the literature on the in-situ formation of polymer films on metal surfaces. Formation of thin polymer films on a metal substrate can be achieved by adsorbing a preformed polymer 1,2 or by forming the polymer in situ. [3][4][5][6][7][8][9][10][11] The motivation for these studies is the desire to form a polymer with a regular two-dimensional morphology that may have novel anisotropic properties. In-situ polymerization has been initiated by photon, electron, and γ-ray irradiation. Radiationinduced chemistry allows for select areas of the substrate to be polymerized, opening the way for the production of positive and negative resists. In addition to the interest in surface modification of metal substrates, in-situ methods for forming polymers in an ultrahigh vacuum allow for further study of the chemistry of the polymer surface and the metal-polymer interface using standard surface analysis techniques.There have been several studies on photoinduced polymerization of adsorbed monomers on metal surfaces. Laser-initiated (514 nm) polymerization of 1,4-dinitrobenzene on Ag colloids was studied by surface-enhanced Raman scattering (SERS). 4 Thick films of 1,4-and 1,3-dinitrobenzene were deposited onto Ag colloids from solution. SERS showed that 1,4-dinitrobenzene polymerized readily on the Ag surface upon CW Ar ion irradiation whereas 1,3-dinitrobenzene did not. Differences in molecular orientation of 1,4-dinitrobenzene compared to 1,3-dinitrobenzene were determined to be the cause of the difference in the photoreactivity of these two isomers on the metal substrate.Ford et al. used a self-assembled monolayer approach to form ordered polymer films by adsorbing 4-(mercap-

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Adsorption and Polymerization of Thiophene on a Ag(111) Surface

Cited by 53 publications

References 24 publications

Adsorption site determination of a large π-conjugated molecule by normal incidence x-ray standing waves: End-capped quaterthiophene on Ag(111)

Adsorption site determination of a large π-conjugated molecule by normal incidence x-ray standing waves: End-capped quaterthiophene on Ag(111)

Electron stimulated desorption of anionic fragments from films of pure and electron-irradiated thiophene

RAIRS and TPD Study of the Direct Photopolymerization of Styrene Thin Films in Ultrahigh Vacuum

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