X-ray photoelectron spectroscopy study of para-substituted benzoic acids chemisorbed to aluminum oxide thin films

Abstract

Articles you may be interested inX-ray photoelectron spectroscopy study on the chemistry involved in tin oxide film growth during chemical vapor deposition processes J. Vac. Sci. Technol. A 31, 01A105 (2013); 10.1116/1.4756898 New insight brought by density functional theory on the chemical state of alaninol on Cu(100): Energetics and interpretation of x-ray photoelectron spectroscopy data J. Chem. Phys. 128, 114709 (2008); 10.1063/1.2888562 X-ray photoelectron spectroscopy study of self-assembled monolayers of alkanethiols on (001) GaAs Novel cyanoterphenyl self-assembly monolayers on Au(111) studied by ellipsometry, x-ray photoelectron spectroscopy, and vibrational spectroscopies J. Chem. Phys. 122, 224707 (2005); 10.1063/1.1893618 1-octadecene monolayers on Si(111) hydrogen-terminated surfaces: Effect of substrate dopingA series of para-substituted, halogenated (F, Cl, Br, and I) benzoic acid monolayers were prepared on the native oxide of aluminum surfaces by solution self-assembly and spin-coating techniques. The monolayers were characterized by x-ray photoelectron spectroscopy (XPS) and water contact angles. Several general trends are apparent. First, the polarity of the solvent is critical to monolayer formation. Protic polar solvents produced low coverage monolayers; in contrast, nonpolar solvents produced higher coverage monolayers. Second, solution deposition yields a higher surface coverage than spin coating. Third, the thickness of the monolayers determined from XPS suggests the plane of the aromatic ring is perpendicular to the surface with the carboxylate functional group most likely binding in a bidentate chelating geometry. Fourth, the saturation coverage ($2.7 Â 10 14 molecules cm À2 ) is independent of the para-substituent.

New insights into oxygen surface coverage and the resulting two-component structure of graphene oxide

“…284.5 and 289 eV to sp 2 C=C aromatic and sp 2 carboxylic/carboxylate groups, respectively. This is readily verified using model compounds: the benzoic acid spectrum contains only contributions at the above mentioned binding energies [48]. However, there are different interpretations regarding the uncertainties have been addressed, and largely resolved, in the abundant literature on oxidized carbon fibers [52]: the general rule of thumb is a shift of 1.5 eV per C-O bond.…”

Steric Inhibition of Metal Penetration in the Fabrication of Metal/Molecule Contacts

“…Water contact angles are <15°on freshly oxidized surfaces. 33 Second, the hydroxyl groups introduce a strong surface dipole, which has a large perturbation on the work function. Previous ultraviolet photoelectron spectroscopy (UPS) measurements reported the work function of a clean aluminum oxide surface to be 3.8 eV.…”

“…Our previous results show these conditions produce saturation coverage. 33 The room-temperature tunneling conductance curves for these monolayers are shown in Figure 3. As the para-substituent was changed from F to Cl to Br to I, the G(V) min decreases from ∼120 to ∼20 mV.…”

“…First, the surface is very hydrophilic. Water contact angles are <15° on freshly oxidized surfaces . Second, the hydroxyl groups introduce a strong surface dipole, which has a large perturbation on the work function.…”

“…Second, by changing the para-substituent we can systematically control the atom in contact with the top metal. Third, we have previously quantified the surface coverage of these monolayers from X-ray photoelectron spectroscopy (XPS) and contact-angle measurements …”