Person:
Díaz Blanco, Cristina

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First Name
Cristina
Last Name
Díaz Blanco
URI
https://hdl.handle.net/20.500.14352/76092
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
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2021 - 20222
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Author: Calleja, Fabián × Subject: 544 ×

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Now showing 1 - 2 of 2
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    Graphene grown on transition metal substrates: Versatile templates for organic molecules with new properties and structures
    (Surface Science Reports, 2022) Díaz Blanco, Cristina; Calleja, Fabián; Vázquez de Parga, Amadeo L.; Martín, Fernando
    The interest in graphene (a carbon monolayer) adsorbed on metal surfaces goes back to the 60’s, long before isolated graphene was produced in the laboratory. Owing to the carbon-metal interaction and the lattice mismatch between the carbon monolayer and the metal surface, graphene usually adopts a rippled structure, known as moir´e, that confers it interesting electronic properties not present in isolated graphene. These moir´e structures can be used as versatile templates where to adsorb, isolate and assemble organic-molecule structures with some desired geometric and electronic properties. In this review, we first describe the main experimental techniques and the theoretical methods currently available to produce and characterize these complex systems. Then, we review the diversity of moir´e structures that have been reported in the literature and the consequences for the electronic properties of graphene, attending to the magnitude of the lattice mismatch and the type of interaction, chemical or physical, between graphene and the metal surface. Subsequently, we address the problem of the adsorption of single organic molecules and then of several ones, from dimers to complete monolayers, describing both the different arrangements that these molecules can adopt as well as their physical and chemical properties. We pay a special attention to graphene/Ru(0001) due to its exceptional electronic properties, which have been used to induce long-range magnetic order in tetracyanoquinodimethane (TCNQ) monolayers, to catalyze the (reversible) reaction between acetonitrile and TCNQ molecules and to efficiently photogenerate large acenes.
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    Efficient photogeneration of nonacene on nanostructured graphene
    (Nanoscale Horizons, 2021) Ayani, Cosme ; Pisarra, Michele; Urgel, José ; Navarro, Juan Jesús; Díaz Blanco, Cristina; Hayashi, Hironobu; Yamada, Hiroko; Calleja, Fabián; Miranda, Rodolfo; Fasel, Román; Martín, Fernando; Vázquez de Parga, Amadeo
    The on-surface photogeneration of nonacene from a-bisdiketone precursors deposited on nanostructured epitaxial graphene grown on Ru(0001) has been studied by means of low temperature scanning tunneling microscopy and spectroscopy. The presence of an unoccupied surface state, spatially localized in the regions where the precursors are adsorbed, and energetically accessible in the region of the electromagnetic spectrum where n–p* transitions take place, allows for a 100% conversion of the precursors into nonacenes. With the help of state-of-the-art theoretical calculations, we show that such a high yield is due to the effective population of the surface state by the incoming light and the ensuing electron transfer to the unoccupied states of the precursors through an inelastic scattering mechanism. Our findings are the experimental confirmation that surface states can play a prominent role in the surface photochemistry of complex molecular systems, in accordance with early theoretical predictions made on small molecules.