Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 11 of 11 results
  • Surfaces and thin films of fullerenes

     Macovez, Roberto; RUDOLF, PETRA
    Date of publication: 2012-03-30
    Book chapter

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Molecular conformation in organic films from quantum chemistry ab initio calculations and second harmonic spectroscopy

     Macovez, Roberto; López, Núria; Mariano, Marina; Maymò, Marc; Martorell Pena, Jordi
    The journal of physical chemistry. Part C, nanomaterials and interfaces
    Date of publication: 2012-11-30
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Identifying molecular species and conformations at surfaces is of interest for both catalytic and biointerfacial research. Here, we present an extinction and second harmonic spectroscopy study of films of crystal violet together with quantum chemistry ab initio calculations on several conformation geometries of this dye. By comparing experimental and theoretical data, we identify the molecular species responsible for the spectral resonances, and we ascribe the nonlinear optical generation to pyramidal conformers with nonzero dipolar hyperpolarizability. Our results, which are consistent with recent findings on alcohol solutions of the same dye, help to settle a long-standing debate and demonstrate that nonlinear second harmonic spectroscopy is a valuable tool for identifying and probing molecular conformation in interfacial systems.

  • Dinámica en sólidos desordenados

     Romanini, Michela; Macovez, Roberto; Ruiz Martin, Maria Dolores; Levit Valenzuela, Rafael; Pardo Soto, Luis Carlos; Del Barrio Casado, Maria; Vispa, Alessandro; Tamarit Mur, Jose Luis
    Participation in a competitive project

     Share

  • Surface hubbard U of alkali fullerides

     Macovez, Roberto
    Journal of electron spectroscopy and related phenomena
    Date of publication: 2011
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Wereport a combined photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES) study of distilled, phase pure films of C60 and the monomeric fullerides Cs6C60, Cs4C60 and fcc RbC60. The separation between the highest energy PES and lowest energy IPES features, which is a measure of the barrier to hopping, is 1.45 eV in Cs4C60 and 0.7 eV in RbC60. This difference is large enough to explain, in a correlated electron picture, the reported differences in electronic mobility between the two stoichoimetries. From the PES-IPES energy separation, the value of the Hubbard U is estimated to be 1.5 eV in closed-shell C60 and Cs6C60, while in Cs4C60 and RbC60 such value is reduced to∼1 and 0.7 eV, respectively. This trend can be only partially understood taking into account the different molecular polarizability and crystal structure of the various stoichiometries. The relatively low values found for open-shell compounds indicate that the bulk Hubbard U is smaller in open-shell fullerides than usually believed, which might help explain superconductivity and the observation of spin-singlets in odd-stoichiometry fullerides.

  • Large Optical-Frequency Shift of Molecular Radiation via Coherent Coupling to an Off-Resonance Plasmon

     Macovez, Roberto; Mariano, Marina; Di Finizio, Sergio; Kozyreff, Gregory; Martorell Pena, Jordi
    Physical review letters
    Date of publication: 2011-08-09
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Molecular X(2) gratings via electron-beam lithography

     Domínguez Juárez, Jorge Luis; Macovez, Roberto; Ujue González, María; Martorell Pena, Jordi
    Applied physics letters
    Date of publication: 2010-07-14
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    We show that the nonlinear optical activity of an organic molecule may be quenched by electron irradiation. Exploiting this effect, we inscribe periodic χ(2) patterns in the molecular films by means of a scanning electron microscope. The second harmonic diffraction efficiency of the resulting χ(2) gratings is measured. The relative intensity of the diffraction orders observed agrees with the expectations for a sheet of nonlinear dipoles with a periodic modulation. No linear diffraction is seen. The present method allows realizing any type of two-dimensional χ(2) pattern with a resolution only limited by the electron beam patterning capabilities.

  • New approaches for the fabrication of photonic structures of nonlinear optical materials

     Carvajal, J J; Peña, A; Kumar, R.; Pujol, M. C.; Mateos, X.; Aguiló, M; Díaz, F; Vázquez De Aldana, J. R.; Méndez, C.; Moreno, P; Roso, L; Trifonov, T; Rodriguez Martinez, Angel; Alcubilla Gonzalez, Ramon; Král, Z; Ferré Borrull, J.; Pallarès Marzal, Josep; Marsal, L F; Finizio, Sergio Di; Martorell, J; Macovez, Roberto
    Journal of luminescence
    Date of publication: 2009-12
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • DINÁMICA DE SOLIDOS ORIENTACIONALMENTE DESORDENADOS

     Pardo Soto, Luis Carlos; Levit Valenzuela, Rafael; Macovez, Roberto; Martinez Garcia, Julio Cesar; Veglio, Nestor Raul; Ruiz Martin, Maria Dolores; Del Barrio Casado, Maria; Rovira Esteva, Muriel; Romanini, Michela; Tamarit Mur, Jose Luis
    Participation in a competitive project

     Share

  • TRANSICIONS DE FASES, POLIMORFISME I DINÀMICA DE LA METAESTABILITAT

     Duarte Correa, Maria Jazmin; Rojas Gregorio, Jose Ignacio; Crespo Artiaga, Daniel; Torra Ferre, Vicenç; Pineda Soler, Eloy; Buti Papiol, Salvador; Salvado Cabre, Nativitat; Del Barrio Casado, Maria; Pardo Soto, Luis Carlos; Ruiz Martin, Maria Dolores; Rovira Esteva, Muriel; Levit Valenzuela, Rafael; Veglio, Nestor Raul; Romanini, Michela; Macovez, Roberto; Flores Garcia, Juan Carlos; Torres Heredia, Victor Elias; Martinez Garcia, Julio Cesar; Serrano Gutierrez, Jorge; Molera Marimon, Judit; Tamarit Mur, Jose Luis
    Participation in a competitive project

     Share

  • Access to the full text
    Measurement of the dispersion of air and of refractive index anomalies by wavelength- dependent nonlinear interferometry  Open access

     Macovez, Roberto; Mariano, Marina; Di Finizio, Sergio; Martorell Pena, Jordi
    Optics express
    Date of publication: 2009-07-27
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    We carry out wavelength-dependent second harmonic interference experiments using thin films of an organic dye as nonlinear optical sources. While the measured difference of refractive index between the fundamental and second harmonic wavelengths follows the theoretical expectation for air in a wide spectral region, anomalous dispersion is observed when the second harmonic light lies in the absorption band of the dye. The sensitivity of the technique to small refractive index variations may prove useful for sensing applications as well as for testing models of light dispersion in weakly dispersing and absorbing media.

  • Nonlinear Optics in the Nano and Micro Dimensions

     Di Finizio, Sergio; Vidal Asensio, Xavier; Domínguez Juárez, Jorge Luis; Botey Cumella, Muriel; Macovez, Roberto; Martorell Pena, Jordi
    Annual International Laser Physics Workshop
    Presentation's date: 2008-07-04
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window