INVESTIGADORES
FUHR Javier Daniel
artículos
Título:
Controlling Carboxyl Deprotonation on Cu(001) by Surface Sn Alloying
Autor/es:
A. CARRERA; L. J. CRISTINA; S. BENGIÓ; A. COSSARO; A. VERDINI; L. FLOREANO; J. D. FUHR; J. E. GAYONE; H. ASCOLANI
Revista:
JOURNAL OF PHYSICAL CHEMISTRY C
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2013 vol. 117 p. 17058 - 17065
ISSN:
1932-7447
Resumen:
We find that for adsorbed terephthalic acid (TPA) molecules surface Sn
alloying deactivates the Cu(001) surface by decoupling the adsorbed
molecules from the substrate. This effect is investigated for the case
of the 0.5 ML phase of the Sn/Cu(001) surface alloy by applying fast
X-ray photoemission spectroscopy, scanning tunneling microscopy,
near-edge X-ray absorption fine structure spectroscopy, and density
functional theory calculations. The experimental results conclusively
show that the deprotonation reaction of the carboxyl groups occurring in
the clean Cu(001) is fully inhibited on this Sn/Cu(001) surface alloy,
which allows the molecules to form two-dimensional arrays stabilized by
[OH···O] hydrogen bonds. The formed arrays exhibit a crystal structure
that is practically indistinguishable from that theoretically obtained
for unsupported TPA sheets, suggesting an extremely weak
molecule/substrate interaction. This is supported by DFT calculations of
the adsorption energy landscape of the TPA sheets formed on the
Sn/Cu(001) template: the lateral variation of the adsorption energy
(corrugation) is estimated to be less than 0.2 eV, with an adsorption
energy per molecule in the range 1.6?1.8 eV and a contribution of each
double [OH···O] bond of 1 eV. Finally, the performed thermal desorption
experiments show that the TPA sheets remain stable on the surface alloy
until their desorption. From these experiments, a value of 1.5 eV was
determined for the desorption energy barrier, which is consistent with
the important contribution of the [OH···O] bonds to the stability of the
sheets as theoretically predicted. The results reported in this study
suggest that a gradual activation of the interaction between the TPA
molecules and the Cu(001) surface will also be obtained for decreasing
Sn coverage.