The synthesis of a novel expanded π-conjugated system, namely benzotri(7-azaindole), BTAI, is rep... more The synthesis of a novel expanded π-conjugated system, namely benzotri(7-azaindole), BTAI, is reported. Its C 3h symmetry along with the integration of six complementary donor and acceptor N-H···N hydrogen bonds in the conjugated structure promote the 2D self-assembly on Au(111) over extended areas. Besides, a perfect commensurability with the gold lattice endows the physisorbed molecular film with a remarkable stability. The structural features of BTAI result in two levels of surface chirality: Firstly, the molecules become chiral upon adsorption on the surface. Then, due to the favorable N-H···N hydrogen bond-directed self-assembly, along with the relative molecular rotation with respect to the substrate, supramolecular chirality manifests in two mirror enantiomorphous domains. Thus, the system undergoes spontaneous chiral resolution. LEED and STM assisted by theoretical simulations have been employed to characterize in detail these novel 2D conglomerates with relevant chiral properties for systems with C 3h symmetry.
Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de... more Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de septiembre de 2016.
The role of the oxidation state of carbon on the early stages of growth of metal oxides was studi... more The role of the oxidation state of carbon on the early stages of growth of metal oxides was studied for the particular case of ZnO deposition on graphene and graphene oxide on SiO2 (G/SiO2 and GO/SiO2, respectively) substrates. The growth was carried out by thermal evaporation of metallic Zn under an oxygen atmosphere at room temperature. This technique permits quasi-equilibrium conditions during the oxide growth, allowing the characterization of the fundamental interaction between ZnO and the graphene-based substrates. Although in both cases ZnO follows a Volmer–Weber growth mode controlled by nucleation at defects, the details are different. In the case of the GO/SiO2 substrate, the nucleation process acts as a bottleneck, limiting the coverage of the complete surface and allowing the growth of very large ZnO structures in comparison to G/SiO2. Moreover, by studying the Zn-LMM Auger spectra, it is shown how the initial nature of the substrate influences the composition of the ZnO ...
This article studies the chemical interaction between ZnO and highly oriented pyrolytic graphite ... more This article studies the chemical interaction between ZnO and highly oriented pyrolytic graphite for as grown and thermally treated samples. In-situ X-ray photoelectron spectroscopy and ex-situ Raman spectroscopy confirm that graphite is affected by these processes, becoming oxidized and defective only in the presence of ZnO clusters that become recrystallized upon thermal re-oxidation processes performed at 400 °C. By comparing these results with other identical experiments performed with ZnO clusters grown on graphene and even with CoO clusters grown on graphite, the present results show how the interaction of the ZnO clusters with graphitic substrates depend on two factors—firstly, the mode of growth and corresponding morphology, and secondly, the reactivity of the graphitic substrates, either graphene or graphite. The results presented here will help us understand the fundamental interactions in ZnO/graphitic heterostructures and to define their operating limits.
Cobalt oxide has experienced a recent increase in research in the last years due to its applicati... more Cobalt oxide has experienced a recent increase in research in the last years due to its applications as supercapacitors [1], electrode materials for Li-ion batteries [2], aside from its traditional applications as magnetoresistant materials [3] or catalysts [4]. A lot of work has been done in the structural and chemical characterization of the growth of this material on metals [5,6], but the growth on oxide and graphite substrates has been less explored. In this research, we have studied the early, intermediate and final stages of growth by reactive evaporation of Co in oxygen atmosphere and room temperature of CoOx supported on HOPG and SiO2. The different stages of growth were analyzed by x-ray photoemission spectroscopy (XPS) and atomic force microscopy (AFM). The chemical analysis of the stages of growth by XPS revealed that for both, the early and intermediate stages of growth on both substrates the Co species were mainly Co 2+ . However, for large coverages (>25 ML) Co 2,3 ...
Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de... more Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de septiembre de 2016.
The synthesis of a novel expanded π-conjugated system, namely benzotri(7-azaindole), BTAI, is rep... more The synthesis of a novel expanded π-conjugated system, namely benzotri(7-azaindole), BTAI, is reported. Its C 3h symmetry along with the integration of six complementary donor and acceptor N-H···N hydrogen bonds in the conjugated structure promote the 2D self-assembly on Au(111) over extended areas. Besides, a perfect commensurability with the gold lattice endows the physisorbed molecular film with a remarkable stability. The structural features of BTAI result in two levels of surface chirality: Firstly, the molecules become chiral upon adsorption on the surface. Then, due to the favorable N-H···N hydrogen bond-directed self-assembly, along with the relative molecular rotation with respect to the substrate, supramolecular chirality manifests in two mirror enantiomorphous domains. Thus, the system undergoes spontaneous chiral resolution. LEED and STM assisted by theoretical simulations have been employed to characterize in detail these novel 2D conglomerates with relevant chiral properties for systems with C 3h symmetry.
Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de... more Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de septiembre de 2016.
The role of the oxidation state of carbon on the early stages of growth of metal oxides was studi... more The role of the oxidation state of carbon on the early stages of growth of metal oxides was studied for the particular case of ZnO deposition on graphene and graphene oxide on SiO2 (G/SiO2 and GO/SiO2, respectively) substrates. The growth was carried out by thermal evaporation of metallic Zn under an oxygen atmosphere at room temperature. This technique permits quasi-equilibrium conditions during the oxide growth, allowing the characterization of the fundamental interaction between ZnO and the graphene-based substrates. Although in both cases ZnO follows a Volmer–Weber growth mode controlled by nucleation at defects, the details are different. In the case of the GO/SiO2 substrate, the nucleation process acts as a bottleneck, limiting the coverage of the complete surface and allowing the growth of very large ZnO structures in comparison to G/SiO2. Moreover, by studying the Zn-LMM Auger spectra, it is shown how the initial nature of the substrate influences the composition of the ZnO ...
This article studies the chemical interaction between ZnO and highly oriented pyrolytic graphite ... more This article studies the chemical interaction between ZnO and highly oriented pyrolytic graphite for as grown and thermally treated samples. In-situ X-ray photoelectron spectroscopy and ex-situ Raman spectroscopy confirm that graphite is affected by these processes, becoming oxidized and defective only in the presence of ZnO clusters that become recrystallized upon thermal re-oxidation processes performed at 400 °C. By comparing these results with other identical experiments performed with ZnO clusters grown on graphene and even with CoO clusters grown on graphite, the present results show how the interaction of the ZnO clusters with graphitic substrates depend on two factors—firstly, the mode of growth and corresponding morphology, and secondly, the reactivity of the graphitic substrates, either graphene or graphite. The results presented here will help us understand the fundamental interactions in ZnO/graphitic heterostructures and to define their operating limits.
Cobalt oxide has experienced a recent increase in research in the last years due to its applicati... more Cobalt oxide has experienced a recent increase in research in the last years due to its applications as supercapacitors [1], electrode materials for Li-ion batteries [2], aside from its traditional applications as magnetoresistant materials [3] or catalysts [4]. A lot of work has been done in the structural and chemical characterization of the growth of this material on metals [5,6], but the growth on oxide and graphite substrates has been less explored. In this research, we have studied the early, intermediate and final stages of growth by reactive evaporation of Co in oxygen atmosphere and room temperature of CoOx supported on HOPG and SiO2. The different stages of growth were analyzed by x-ray photoemission spectroscopy (XPS) and atomic force microscopy (AFM). The chemical analysis of the stages of growth by XPS revealed that for both, the early and intermediate stages of growth on both substrates the Co species were mainly Co 2+ . However, for large coverages (>25 ML) Co 2,3 ...
Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de... more Trabajo presentado en la conferencia Fuerzas y Tunel (FyT2016), celebrada en Girona del 5 al 7 de septiembre de 2016.
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