Identification of transitions into Rydberg states in the X-ray absorption spectra of condensed long-chain alkanes

Bagus, Paul S.; Weiß, K.; Schertel, Andreas; Wöll, Ch.; Braun, W.; Hellwig, Ch.; Jung, Christian

doi:10.1016/0009-2614(95)01315-6

Cited by 170 publications

(206 citation statements)

References 15 publications

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“…29 Peak ''c'' corresponds to the transition of C 1s of the aliphatic carbons to the C-H* anti-bonding orbitals ͑Rydberg resonance͒ in both SAMs prepared from alkanethiols 1 or 2. 30 Peaks ''d'' and ''e'' correspond to the same transitions as peaks ''a'' and ''b,'' respectively, except the final anti-bonding orbital is the higherlying 2 * . Peak ''f'' corresponds to the transition of C 1s of the aliphatic carbons to the C-C * anti-bonding orbitals in both SAMs prepared from alkanethiols 1 or 2.…”

Section: Resultsmentioning

confidence: 95%

Dipole-induced structure in aromatic-terminated self-assembled monolayers—A study by near edge x-ray absorption fine structure spectroscopy

Luk

Abbott

Crain

et al. 2004

The Journal of Chemical Physics

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The structure of self-assembled monolayers presenting aromatic rings at a surface is studied by near edge x-ray absorption fine structure spectroscopy ͑NEXAFS͒. Fluorine substitution at asymmetric positions in the aromatic rings is used to generate a layer of dipoles at the surface of the monolayer. We find that fluorine substituted aromatic rings are more ordered than unsubstituted aromatic rings by a factor of two based on the polarization dependence of the lowest C 1s to * transition, which is associated with transitions from phenyl carbons attached to hydrogens. This result is consistent with the influence of dipole-dipole interactions and quadrupolar interactions between the aromatic groups due to the substitution of fluorine atoms. The work also serves to illustrate how subtle variations in the orientation of an end group of a self-assembled monolayer can be determined by using NEXAFS.

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Section: Resultsmentioning

confidence: 95%

Dipole-induced structure in aromatic-terminated self-assembled monolayers—A study by near edge x-ray absorption fine structure spectroscopy

Luk

Abbott

Crain

et al. 2004

The Journal of Chemical Physics

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“…22 -24 The long alkyl chain in ODTMS means that the C 1s NEXAFS spectrum is particularly well suited to this type of study, because it contains features that are selectively sensitive to the polarization of the incident synchrotron radiation. 25,26 Previous work by Houssiau et al has indicated that, although oscillatory adsorption is observed for octyltrichlorosilane in non-aqueous solvents, it is not apparent for the longer chain octadecyltrichlorosilane molecule, suggesting that this process may not be a general phenomenon. 20,21 Our observation of oscillatory adsorption behaviour for ODTMS, which was similar to that observed for PTMS, is therefore somewhat surprising and represents the first observation of this phenomenon for such a long-chain silane.…”

Section: Introductionmentioning

confidence: 93%

Adsorption and orientation kinetics of self‐assembled films of octadecyltrimethoxysilane on aluminium oxide surfaces

Thomsen¹,

Watts²,

Cotton³

et al. 2005

Surface & Interface Analysis

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X-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy have been used to study the time-dependent adsorption and molecular orientation behaviour of octadecyltrimethoxysilane (ODTMS) on native aluminium oxide surfaces. By measuring the adsorption isotherm using XPS, we show that ODTMS molecules exhibit oscillatory adsorption. The oscillatory adsorption behaviour for ODTMS is analogous to that observed for its simpler short-chain 'cousin' -propyltrimethoxysilane (PTMS) -and suggests that the length of the functional alkyl chain on an organosilane does not have a significant influence upon the oscillatory adsorption mechanism. The oscillation in the ODTMS adsorption isotherm shows a maximum and a minimum in coverage at an adsorption time of ∼30 and ∼65 s, respectively, for a 0.75% ODTMS solution in a 90% ethanol-10% water mixture at pH 4. The time-dependent orientation behaviour of the ODTMS molecules during adsorption was examined using angular-dependent carbon K-edge NEXAFS spectroscopy. We show that the alignment of the ODTMS film changes systematically with deposition time and appears to be correlated with coverage measurements obtained using XPS. In particular, by combining the XPS and NEXAFS results we demonstrate that the minimum ODTMS coverage corresponds to a film whose alignment appears to be predominantly randomized.

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“…28,29 In the solid phase, Rydberg transition contributions to these features are not expected, 30 although theoretical studies have proposed that there is a significant 29 or partial 28 Rydberg contribution to these features in polyethylene. The higher energy C 1s f σ* C-C and C 1s f σ* C-O transitions are assigned in accordance to previously published assignments on similar species.…”

Section: Distinguishing Urea and Carbamatementioning

confidence: 99%

“…11 polymers, particularly when the "spatial extent" of π* delocalization in the polymer is properly accounted for in the molecular model structure. 36,22 The effect of "σ-delocalization" and the contentious issue of Rydberg transitions 29 in the core excitation spectroscopy of polymers deserve further experimental and theoretical study. Figure 3 presents the C 1s spectra of four TDI polyurethane polymers synthesized with poly(propylene oxide) polyether polyols of different molecular weight (250, 700, 1500, and 3000 MW), together with the C 1s spectrum of poly(propylene oxide).…”

Section: Distinguishing Urea and Carbamatementioning

confidence: 99%

Near-Edge X-ray Absorption Fine Structure Spectroscopy of MDI and TDI Polyurethane Polymers

et al. 1999

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The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to differences in key chemical components of polyurethane polymers is presented. Carbon 1s NEXAFS spectra of polyurethane polymers made from 4,4′-methylene di-p-phenylene isocyanate (MDI) and toluene diisocyanate (TDI) isocyanate monomers illustrate that there is an unambiguous spectroscopic fingerprint for distinguishing between MDIbased and TDI-based polyurethane polymers. NEXAFS spectra of MDI and TDI polyurea and polyurethane models show that the urea and carbamate (urethane) linkages in these polymers can be distinguished. The NEXAFS spectroscopy of the polyether component of these polymers is discussed, and the differences between the spectra of MDI and TDI polyurethanes synthesized with polyether polyols of different molecular composition and different molecular weight are presented. These polymer spectra reported herein provide appropriate model spectra to represent the pure components for quantitative microanalysis.

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Identification of transitions into Rydberg states in the X-ray absorption spectra of condensed long-chain alkanes

Cited by 170 publications

References 15 publications

Dipole-induced structure in aromatic-terminated self-assembled monolayers—A study by near edge x-ray absorption fine structure spectroscopy

Dipole-induced structure in aromatic-terminated self-assembled monolayers—A study by near edge x-ray absorption fine structure spectroscopy

Adsorption and orientation kinetics of self‐assembled films of octadecyltrimethoxysilane on aluminium oxide surfaces

Near-Edge X-ray Absorption Fine Structure Spectroscopy of MDI and TDI Polyurethane Polymers

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