Person: Bañares Morcillo, Luis
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First Name
Luis
Last Name
Bañares Morcillo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
Identifiers
44 results
Search Results
Now showing 1 - 10 of 44
Item Holographic gratings implemented in a photopolymerizable glass: Application to femtosecond laser pulses shaping(22nd Congress of the International Commission for Optics: Light for the Development of the World, 2011) Hernández Garay, María de la Paz; Martínez Matos, Óscar; González Izquierdo, Jesús; Calvo Padilla, María Luisa; Cheben, Pavel; Bañares Morcillo, LuisWe present the capability of the holographic gratings implemented in photopolymerizable glasses to be applied in spatial and spectral manipulation of femtosecond laser pulses. For this purpose we used volume phase holographic gratings recorded by the interference of two monochromatic and coherent beams coming from a Nd-YAG continuous laser. We carried out experiments to determine the main features of the diffracted beams originated by the interaction of volume holographic phase grating structures with femtosecond pulses arising from the fundamental emission of an amplified Ti: sapphire laser system and its second harmonic. Meanwhile we have performed experiments to determine its damage threshold indicating that this material is an excellent candidate for intense-fields and ultrashort laser pulse applications.Item Femtosecond spectral pulse shaping with holographic gratings recorded in photopolymerizable glasses(Optics Express, 2011) Martínez Matos, Óscar; Hernández Garay, María de la Paz; González Izquierdo, Jesús; Calvo Padilla, María Luisa; Vaveliuk, Pablo; Cheben, Pavel; Bañares Morcillo, LuisThe majority of the applications of ultrashort laser pulses require a control of its spectral bandwidth. In this paper we show the capability of volume phase holographic gratings recorded in photopolymerizable glasses for spectral pulse reshaping of ultrashort laser pulses originated in an Amplified Ti: Sapphire laser system and its second harmonic. Gratings with high laser induce damage threshold (LIDT) allowing wide spectral bandwidth operability satisfy these demands. We have performed LIDT testing in the photopolymerizable glass showing that the sample remains unaltered after more than 10 million pulses with 0,75 TW/cm^2 at 1 KHz repetition rate. Furthermore, it has been developed a theoretical model, as an extension of the Kogelnik's theory, providing key gratings design for bandwidth operability. The main features of the diffracted beams are in agreement with the model, showing that non-linear effects are negligible in this material up to the fluence threshold for laser induced damage. The high versatility of the grating design along with the excellent LIDT indicates that this material is a promising candidate for ultrashort laser pulses manipulations.Item Effect of Organic Stabilizers on Silver Nanoparticles Fabricated by Femtosecond Pulsed Laser Ablation(Applied Sciences, 2017) Díaz Núñez, Pablo; González Izquierdo, Jesús; González Rubio, Guillermo; Guerrero Martínez, Andrés; Rivera, Antonio; Perlado, José; Bañares Morcillo, Luis; Peña-Rodríguez, OvidioLaser ablation has several advantages over the chemical synthesis of nanoparticles due to its simplicity and because it is a faster and cleaner process. In this paper, we use femtosecond laser ablation to generate highly concentrated silver colloidal nanoparticle solutions. Those high concentrations usually lead to agglomeration of the nanoparticles, rendering the solution nearly useless. We employ two different organic stabilizers (hexadecyltrimethylammonium bromide, CTAB, and polyvinylpyrrolidone, PVP) to avoid this problem and study their effect on the nanoparticle size distribution, structural characteristics, and the solution concentration.Item Generation of femtosecond paraxial beams with arbitrary spatial distribution(Optics Letters, 2010) Martínez Matos, Óscar; Rodrigo Martín-Romo, José Augusto; Hernández Garay, María de la Paz; Izquierdo González, Jesús; Weigand Talavera, Rosa María; Calvo Padilla, María Luisa; Cheben, Pavel; Vaveliuk, Pablo; Bañares Morcillo, LuisWe present an approach to generate paraxial laser beams with arbitrary spatial distribution in the femtosecond time regime. The proposed technique is based upon a pair of volume phase holographic gratings working in parallel arrangement. It exploits the spatial coherence properties of the incoming laser beam in a compact and robust setup that mitigates angular and spatial chirp. The gratings were recorded in a photopolymerizable glass with a high optical damage threshold and a large optical throughput. Setup performance is studied and experimentally demonstrated by generating Laguerre-Gaussian femtosecond pulses.Item Contribution of resonance energy transfer to the luminescence quenching of upconversion nanoparticles with graphene oxide(Journal of Colloid and Interface Science, 2020) Méndez González, Diego; Gómez Calderón, Óscar; Melle Hernández, Sonia; González Izquierdo, Jesús; Bañares Morcillo, Luis; López Díaz, David; Velazquez Salicio, M. Mercedes; López Cabarcos, Enrique; Rubio Retama, Benito Jorge; Laurenti, MarcoUpconversion nanoparticles (UCNP) are increasingly used due to their advantages over conventional fluorophores, and their use as resonance energy transfer (RET) donors has permitted their application as biosensors when they are combined with appropriate RET acceptors such as graphene oxide (GO). However, there is a lack of knowledge about the design and influence that GO composition produces over the quenching of these nanoparticles that in turn will define their performance as sensors. In this work, we have analysed the total quenching efficiency, as well as the actual values corresponding to the RET process between UCNPs and GO sheets with three different chemical compositions. Our findings indicate that excitation and emission absorption by GO sheets are the major contributor to the observed luminescence quenching in these systems. This challenges the general assumption that UCNPs luminescence deactivation by GO is caused by RET. Furthermore, RET efficiency has been theoretically calculated by means of a semiclassical model considering the different nonradiative energy transfer rates from each Er3+ ion to the GO thin film. These theoretical results highlight the relevance of the relative positions of the Er3+ ions inside the UCNP with respect to the GO sheet in order to explain the RET-induced efficiency measurements.Item Intracellular pH-Induced Tip-to-Tip Assembly of Gold Nanorods for Enhanced Plasmonic Photothermal Therapy(ACS Omega, 2016) Ahijado Guzmán, Rubén; Bañares Morcillo, Luis; Guerrero Martínez, Andrés; López Montero, Iván; Tardajos Rodríguez, Gloria María; González Rubio, Guillermo; Izquierdo, Jesús G.; Calzado Martín, Alicia; Calleja, MontserratThe search for efficient plasmonic photothermal therapies using nonharmful pulse laser irradiation at the near-infrared (NIR) is fundamental for biomedical cancer research. Therefore, the development of novel assembled plasmonic gold nanostructures with the aim of reducing the applied laser power density to a minimum through hot-spot-mediated cell photothermolysis is an ongoing challenge. We demonstrate that gold nanorods (Au NRs) functionalized at their tips with a pH-sensitive ligand assemble into oligomers within cell lysosomes through hydrogen-bonding attractive interactions. The unique intracellular features of the plasmonic oligomers allow us to significantly reduce the femtosecond laser power density and Au NR dose while still achieving excellent cell killing rates. The formation of gold tip-to-tip oligomers with longitudinal localized surface plasmon resonance bands at the NIR, obtained from low-aspect-ratio Au NRs close in resonance with 800 nm Ti:sapphire 90 fs laser pulses, was found to be the key parameter for realizing the enhanced plasmonic photothermal therapy.Item Threshold Photoelectron Spectroscopy of the CH2I, CHI, and CI Radicals(The Journal of Physical Chemistry A, 2021) Chicharro, David V.; Hrodmarsson, Helgi Rafn; Bouallagui, Aymen; Zanchet, Alexandre; Loison, Jean-Christophe; García, Gustavo A.; García Vela, Alberto; Bañares Morcillo, Luis; Marggi Poullaín, SoniaVUV photoionization of the CHnI radicals (with n = 0, 1, and 2) is investigated by means of synchrotron radiation coupled with a double imaging photoion-photoelectron coincidence spectrometer. Photoionization efficiencies and threshold photoelectron spectra (TPES) for photon energies ranging between 9.2 and 12.0 eV are reported. An adiabatic ionization energy (AIE) of 8.334 ± 0.005 eV is obtained for CH2I, which is in good agreement with previous results [8.333 ± 0.015 eV, Sztáray et al. J. Chem. Phys. 2017, 147, 013944], while for CI an AIE of 8.374 ± 0.005 eV is measured for the first time and a value of ∼8.8 eV is estimated for CHI. Ab initio calculations have been carried out for the ground state of the CH2I radical and for the ground state and excited states of the radical cation CH2I + , including potential energy curves along the C−I coordinate. Franck−Condon factors are calculated for transitions from the CH2I(X̃ 2 B1) ground state of the neutral radical to the ground state and excited states of the radical cation. The TPES measured for the CH2I radical shows several structures that correspond to the photoionization into excited states of the radical cation and are fully assigned on the basis of the calculations. The TPES obtained for the CHI is characterized by a broad structure peaking at 9.335 eV, which could be due to the photoionization from both the singlet and the triplet states and into one or more electronic states of the cation. A vibrational progression is clearly observed in the TPES for the CI radical and a frequency for the C−I stretching mode of 760 ± 60 cm−1 characterizing the CI+ electronic ground state has been extracted.Item Femtosecond predissociation dynamics of ethyl iodide in the B-band(Physical Chemistry Chemical Physics, 2019) Murillo Sánchez, Marta Luisa; Marggi Poullaín, Sonia; Loriot, Vincent; Corrales, Maria Eugenia; Bañares Morcillo, LuisFemtosecond velocity map imaging to disentangle the electronic predissociation of ethyl iodide in the B-band.Item Control of ultrafast molecular photodissociation by laser-field-induced potentials(Nature Chemistry, 2014) Corrales, María Eugenia; González-Vázquez, Jesús; Balerdi, Garikoitz; Sola Reija, Ignacio; Nalda, Rebeca de; Bañares Morcillo, LuisItem Femtosecond laser induced damage characterization of transmission volume phase gratings(Applied physics letters, 2014) Martínez Matos, Óscar; Hernández Garay, María de la Paz; Izquierdo, J. G.; Vaveliuk, Pablo; Bañares Morcillo, Luis; Calvo Padilla, María LuisaA procedure to characterize the induced damage and the incubation effects in volume transmission gratings under femtosecond laser pulse train illumination is presented. It was also developed a formalism that explains the damage processes. Our proposal was employed on glass gratings to show the effectiveness of the method and its potential to design transmission gratings with enhanced laser induced damage threshold. This procedure is able to be extended to any transmission grating composed by chemically non-uniform material, opening up new perspectives to femtosecond laser pulse shaping.