Browsing by Author "Gence, Loik"

Now showing 1 - 14 of 14
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    Design of microwave antennas for nitrogen-vacancy centers applications
    (2018) Ortiz Moreno, Ari Rolando; Maze Ríos, Jerónimo; Gence, Loik; Pontificia Universidad Católica de Chile. Facultad de Física
    Nitrogen-vacancy centers in diamond are promising candidates for a wide range of applications due to their quantum sensing capabilities at room temperature and easy optical readout and manipulation by means of confocal microscopy and the application of microwave radiation. Applying microwave radiation is not a trivial task depending on the application. If a single NV center is addressed, then a thin (20 —m diameter) copper wire is sufficient if the NV is within 50 —m from the wire. However in a large area with a lot of NV centers that must be addressed simultaneously with a homogeneous microwave intensity, then a more specialized microwave antenna is required. Towards this goal, a complete procedure for developing microstrip antennas for NV centers applications is presented. In order to drive all NV centers that point along a given direction with the same intensity, an antenna with a uniform intensity over this area is needed, which is not a trivial task. At a given power, there is a compromise between a uniform intensity and high intensity. This procedure includes the antenna design using optical lithography in order to achieve the desired spatial resolution, fabrication and testing using a vector network analyzer and different diamond samples. The fabricated antennas reached a maximum transmission of around 40% near the desired frequency (2.87 GHz), a 100 MHz bandwidth and are capable of resolving electronic spin resonance with a maximum contrast of 22%.
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    Direct reconstruction of two ultrashort pulses based on non-interferometric frequency-resolved optical gating
    (OSA - The Optical Society, 2021) Hidalgo-Rojas, Diego; Rojas-Aedo, Ricardo; Wheatley, Robert A.; Gence, Loik; Seifert, Birger
    © 2021 Optical Society of America.We describe a non-interferometric ultrashort-pulse measurement technique based on frequency-resolved optical gating (FROG) with which pulses can be reconstructed directly, i.e. non-iteratively. Two different FROG spectrograms are measured, which represent the only information required to reconstruct the amplitudes and phases of two independent input pulses. The direct reconstruction method is demonstrated with a single-shot FROG setup used to obtain the spectrograms generated from two synchronized input pulses. To demonstrate and determine the reconstruction quality for complex pulses, a programmable pulse shaper is used to modify the pulses sourced from a Kerr-lens mode-locked Ti:sapphire oscillator.
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    Doped Poly(3-hexylthiophene) Coatings onto Chitosan: A Novel Approach for Developing a Bio-Based Flexible Electronic
    (2020) Bonardd Salvador, Sebastián Ignacio; Morales, Natalia; Gence, Loik; Saldías Barros, César Antonio; Ángel Figueroa, Felipe Alfonso; Kortaberria, G.; Leiva Campusano, Ángel
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    Electrochemically template-grown multi-segmented gold-conducting polymer nanowires with tunable electronic behavior
    (2009) Callegari, V.; Gence, Loik; Melinte, S.; Demoustier-Champagne, S.
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    Engineering nonlinear electrical behavior with asymmetric multisegmented polymer-metal nanowires
    (2014) Gence, Loik; Callegari, V.; Demoustier Champagne, S.; Duvail, J. L.
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    Epitaxial growth and electrical transport properties of Cr2GeC thin films
    (2011) Eklund, P.; Bugnet, M.; Mauchamp, V.; Dubois, S.; Tromas, C.; Jensen, J.; Piraux, L.; Gence, Loik; Jaouen, M.; Cabioch, T.
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    Femtogram-controlled synthesis and self-aligned fabrication of polyaniline micro- and nanostructures
    (2010) Vlad, A.; Yunus, S.; Attout, A.; Serban, D.A.; Gence, Loik; Faniel, S.; Gohy, J.F.; Bertrand, P.; Melinte, S.
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    High performance Li-, Na-, and K-ion storage in electrically conducting coordination polymers
    (2022) Wang, Jiande; Guo, Xiaolong; Apostol, Petru; Liu, Xuelian; Robeyns, Koen; Gence, Loik; Morari, Cristian; Gohy, Jean-Francois; Vlad, Alexandru
    Coordination polymers (CPs) made of redox-active organic moieties and metal ions emerge as an important class of electroactive materials for battery applications. However, the design and synthesis of high voltage alkali-cation reservoir anionic CPs remains challenging, hindering their practical applications. Herein, we report a family of electrically conducting alkali-cation reservoir CPs with the general formula of A(2)-TM-PTtSA (wherein A = Li+, Na+, or K+; TM = Fe2+, Co2+, or Mn2+; and PTtSA = benzene-1,2,4,5-tetra-methylsulfonamide). The incorporation of transition metal centers not only enables intrinsic high electrical conductivity, but also shows an impressive redox potential increase of as high as 1 V as compared to A(4)-PTtSA analogues, resulting in a class of organometallic cathode materials with a high average redox potential of 2.95-3.25 V for Li-, Na- and K-ion batteries. A detailed structure - composition - physicochemical properties - performance correlation study is provided relying on experimental and computational analysis. The best performing candidate shows excellent rate capability (86% of the nominal capacity retained at 10C rate), remarkable cycling stability (96.5% after 1000 cycles), outstanding tolerance to low carbon content (5 wt%), high mass loading (50 mg cm(-2)), and extreme utilisation conditions of low earth orbit space environment tests. The significance of the disclosed alkali-ion reservoir cathodes is further emphasized by utilizing conventional Li-host graphite anode for full cell assembly, attaining a record voltage of 3 V in an organic cathode Li-ion proof-of-concept cell.
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    New Benzotrithiophene-Based Molecules as Organic P-Type Semiconductor for Small-Molecule Organic Solar Cells
    (2023) Castillo, Cristian; Aracena, Andres; Ballesteros, Luis; Neculqueo, Gloria; Gence, Loik; Quero, Franck
    A new benzotrithiophene-based small molecule, namely 2,5,8-Tris[5-(2,2-dicyanovinyl)-2-thienyl]-benzo[1,2-b:3,4-b ':6,5-b '']-trithiophene (DCVT-BTT), was successfully synthesized and subsequently characterized. This compound was found to present an intense absorption band at a wavelength position of similar to 544 nm and displayed potentially relevant optoelectronic properties for photovoltaic devices. Theoretical studies demonstrated an interesting behavior of charge transport as electron donor (hole-transporting) active material for heterojunction cells. A preliminary study of small-molecule organic solar cells based on DCVT-BTT (as the P-type organic semiconductor) and phenyl-C61-butyric acid methyl ester (as the N-type organic semiconductor) exhibited a power conversion efficiency of 2.04% at a donor: acceptor weight ratio of 1:1.
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    Photophysics of a single quantum emitter based on vanadium phthalocyanine molecules
    (2024) Escalante, Richard A.; Athpal, Mohan C.; Ruiz-Tagle, Catalina; Lvarado, Vicente H.; Pinto, Felipe; Martinez, Luis J.; Gence, Loik; Garcia, Griselda; Gonzalez, Iyan A.; Maze, Jeronimo R.
    Single quantum emitters play a fundamental role in the development of quantum technologies such as quantum repeaters, and quantum information processing. Isolating individual molecules with stable optical emission is an essential step for these applications, especially for those molecules that present large coherence times at room temperature. Among them, vanadium-oxide phthalocyanine (VOPc) molecules stand out as promising candidates due to the large coherence times of their ground state electronic spin, which are on the order of microseconds when measured in the ensemble. However, the optical properties of such VOPc molecules at the single emitter level have not yet been reported. Here we show that single VOPc molecules with stable optical properties at room temperature can be isolated. We find that the optical response of the molecule under laser illumination of different polarizations agrees well with a system having pyramidal C4vsymmetry. 4 v symmetry. Furthermore, we provide theoretical calculations that support our experimental findings and provide insight into the role of phonons and the internal electronic structure of the molecule. These results demonstrate that this single paramagnetic molecule can function as a single quantum emitter while displaying optical stability under ambient conditions to have their intrinsic properties investigated.
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    Self-seeded electrochemical growth of ZnO nanorods using textured glass/Al-doped ZnO substrates
    (2014) Antohe, Viad Andrei; Mickan, Martin; Henry, Frederic; Delamare, Romain; Gence, Loik; Piraux, L.
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    Solid solution effects in the Ti2Al(CxNy) MAX phases: Synthesis, microstructure, electronic structure and transport properties
    (2014) Yu, Wenbo; Mauchamp, Vincent; Cabioch, Thierry; Magne, Damien; Gence, Loik; Piraux, L.; Gauthier Brunet, V.; Dubois, Sylvain
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    Structural, optoelectronic and photo-thermoelectric properties of crystalline alloy CuAlxFe1-xO2 delafossite oxide materials
    (2020) Wheatley, Robert Alastair; Roble Albeal, Martín Cristián; Gence, Loik; Acuña Porras, Camilo; Guzmán de la Cerda, Diego José Edgardo; Vojkovic Lagno, Smiljan Andrej; Seifert, Birger; Wallentowitz, Sascha; Volkmann, Ulrich; Díaz, Donovan; Rojas Aedo, R.; Hidalgo Rojas, D.
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    Wrinkled titanium nitride nanocomposite for robust bendable electrodes
    (2019) Gence, Loik; Escalona, M.; Castillo, C.; Quero, F.; Saikia, P.; Wheatley, Robert Alastair; Diaz-Droguett, D.E.; Retamal Ponce, María José; Volkmann, Ulrich; Bhuyan, Heman