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About Omics Group

About Omics Group.

yael-fitzgerald
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About Omics Group

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  1. About Omics Group OMICS Group International through its Open Access Initiative is committed to make genuine and reliable contributions to the scientific community. OMICS Group hosts over 400 leading-edge peer reviewed Open Access Journals and organize over 300 International Conferences annually all over the world. OMICS Publishing Group journals have over 3 million readers and the fame and success of the same can be attributed to the strong editorial board which contains over 30000 eminent personalities that ensure a rapid, quality and quick review process. 

  2. About Omics Group conferences • OMICS Group signed an agreement with more than 1000 International Societies to make healthcare information Open Access. OMICS Group Conferences make the perfect platform for global networking as it brings together renowned speakers and scientists across the globe to a most exciting and memorable scientific event filled with much enlightening interactive sessions, world class exhibitions and poster presentations • Omics group has organised 500 conferences, workshops and national symposium across the major cities including SanFrancisco,Omaha,Orlado,Rayleigh,SantaClara,Chicago,Philadelphia,Unitedkingdom,Baltimore,SanAntanio,Dubai,Hyderabad,Bangaluru and Mumbai.

  3. Quantum interferenceeffects and molecularelectronics Philippe Lafarge Université Paris Diderot, CNRS, Paris, France philippe.lafarge@univ-paris-diderot.fr Optics 2014 - sept. 10, 2014

  4. Quantum interference in mesoscopicsystems Aharonov-Bohmeffect in a metal ring phase coherent transport PQM = |A1 + A2|2 quantum interference phase shift controlled by magnetic flux = pF/F0 R. A. Webb et al., Phys. Rev. Lett. 54, 2696 (1985)

  5. Molecularelectronics • Molecularjunctions • Quantum interference • Simulations • Experimentalresults • Conclusions and perspectives • MOLECULES • Nanoscalestructures • chemicallyactive • Cost-effective Need to probe the electronicproperties of molecules ! Electronic components made withmolecules ? Molecularjunctions D. Fracasso et al. J. Am. Chem. Soc. 2011,133, 9556-9563 R. McCreery et al. Phys. Chem. Chem. Phys.2013, 15, 1065 M. L. Perrin et al. Nat Nano 2013, 8, 282-287 Monolayermolecularjunctions Based on self assembledmonolayers (SAMs) Mechanicallycontrolled break-junctions One or a few moleculesconnected Solid state planarjunction Millions of molecules are connectedthanks to electrografting

  6. Molecularjunctions • Quantum interference • Simulations • Experimentalresults • Conclusions and perspectives Quantum interference • The connectionbetween the molecule and the electrodes influences the • electronicpropertiesdescribed by the electronic transmission probabilityTLR(E) Electron transport through a single benzenemoleculeconnected in ortho, para or meta. L L R R ortho para meta L TLR (EF) ≠ 0 TLR (EF) = 0 R Destructive QI No QI P. Sautet, C. Joachim, Chem. Phys. Lett., 153, 511 (1988) T. Markussen et al. Nano Lett. 10, 4260-4265 (2010) C. R. Arroyo et al. Ang.Chem., 125, 3234-3237 (2013)

  7. Molecularjunctions • Quantum interference • Simulations • Experimentalresults • Conclusions and perspectives QI and molecular structure linearlyconjugated cross conjugated R Anthracene (AC) Anthraquinone (AQ) L para MOLECULE para L R • Molecularjunctions Energy diagrams (LocalizedMolecularOrbitals) Only 1 pathallowed 2 phase-opposedelectronicpaths Constant transmission functionatEf Antiresonance in the transmission function T(Ef) = 0 No QI Destructive QI G. Solomon et al. ChemPhysChem, 10, 257-264 (2009) C.M.Guédon et al. Nat Nano. 7, 305-309(2012)

  8. Molecularjunctions • Quantum interference • Simulations • Experimentalresults • Conclusions and perspectives First experimentalevidences • In SAMs of AC and AQ arylethynylenethiolateswith eutecticGa-In top contacts D. Fracasso et al., JACS 133, 9556 (2011) IAQ(V) < IAC(V) • Froman indirectmeasurement of AQ and AC basedSAMs, statisticalanalysis C.M.Guédon et al. Nat Nano. 7, 305-309 (2012) two-dimensionalhistograms C-AFM AC-DT AQ-MT dI/dV vs V • In AQ basedmolecularjunctionsfrom a directmeasurementof the conductance curves Rabacheet al., JACS 135, 10218 (2013) 300 K tunneling barriermodel 4 K 30 x 30 mm2

  9. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Transmission functioncalculation • Tight binding approach applied to charge transport (KWANT) • Key roleplayed by the way the molecules are connected to the electrodes. Para - anthracene Meta-anthracene Para-anthraquinone Parameters On site energies= 0eV / Couplingenergies = -3eV / Coupling to the electrodes= -1eV C.W. Groth et al. a software package for quantum transport, arXiv: 1309.2926

  10. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Simulations for anthracene • One meta connection in a chainisenough to makeQI occur para-meta-para para-para-para para-para-meta no QI QI QI para meta para para meta para para para para C.W. Groth et al. a software package for quantum transport, arXiv: 1309.2926

  11. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Recenttheoreticalpredictions • Influence of the temperature on QI effects • No thermalactivation • Dependence on the alignment of the transmission nodeand the Fermi level(blue and redlines) • el-ph interactions (solidlines) LUMO T(E) ΔEF E HOMO • Structures in the dI/dVcurves • Stepsvisible a low T withel-ph interactions (solid blue line), notvisibleat RT (solidred line) dI/dV (G0) T. Markussen et al. Phys.Rev.B, 89, 085420 (2014) Biasvoltage (V)

  12. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Fabrication of the junctions Bottomelectrode UV light Au Ti resist SiO2 Si Optical mask Optical lithography Development Lift off Metallicdeposition Postiveresistwith a positive mask To carve the design of the electrode Au ~ 50nm Ti ~ 2-3nm Aceton bath Top electrode electrografting Development Optical lithography Metallicdeposition + lift off

  13. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Fabrication of the junctions Formation of organic film by reduction of diazoniumsalt AQ precursor AQ diazoniumsalt ACN NBu4BF4 Au +e- 9,10-dioxo-1-anthracenediazonium (AQD) P. Martin, J.-C. Lacroix, ITODYS lab, Paris Diderot University Finalsolid state planar junctions(cross bar geometry) Au junction Molecularlayer Au N2+ NH2 Crossed bar geometryjunctions (opticalimage x 20) Samples made with 24 junctions of 20x20μm2 Profileview(schematic)

  14. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Conductance measurements • Au/ AQ /Aujunctions G (V) vs biasvoltage G (V = 0) vs biasvoltage Junction 2 Junction 1 20x20μm2 20x20μm2 • Antiresonancedipat 4K, lowervisibilityat 300K • Temperature dependentstructuresatlow T

  15. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Conductance vs temperature G (V= 0) vs temperature Experimentalfit ! T. Markussen, 2014 private communication Energy of the structures vs the position • Experimentalbehaviour(blue line) similarto the onepredictedfor single moleculejunctionswith el-phinteractions (red line) • Decoherence by electron phononcoupling ? Vn = 2(ε + nhν)

  16. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Anthracenebasedjunctions • Au / AC /Aubasedjunctions G (V = 0) vs biasvoltage G (V) vs biasvoltage Junction 3 Junction 4 20x20μm2 20x20μm2 • Antiresonancedipat 4K, lowervisibilityat 300K as for the AQ-basedjunctions • Temperature dependentstructuresatlow T

  17. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Temperaturedependence G (V= 0) vs temperature Energy of the structures vs the position U (mV) Vn = 2(ε + nhν) n° peak • Experimentalbehavioursimilarto the onepredicted for single and AQ basedjunctions • Decoherence by electron phononcoupling ? • Samevibrationalmodesas for the AQ excited

  18. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Molecularjunction and tunneling • QI vs tunnel behaviour Metallic tunnel junctions Al / Al2O3 /Al Al (50nm) Al2O3 (~ nm) Al(50nm) Differentshapesatlow T 4K

  19. Molecularjunctions • Quantum interferences • Simulations • Experimentalresults • Conclusions and perspectives Conclusions and perspectives • Large area solid state moleculesbasedjunctions(with AQ, AC, oxides…) • Direct measurement of large antiresonancedipin dI/dVcurves with a strong temperature dependence. • Additionalstructuresatlow T thatcould be the signatures of vibrationalmodes of the organiclayer. • Giantthermoelectriceffectpredicted in molecularjunctionswhere QI occur… J.P. Bergfield and C.A. Stafford, NanoLett. 9, 3072 (2009) J.P. Bergfield, M.A. Solis and C.A. Stafford, ACS Nano 4, 5314 (2010) μ-μnode(eV)

  20. Thankyou MPQLab, Paris Diderot University Maria Luisa Della Rocca, Clément Barraud, Charlotte Bessis, Julien Chaste, Philippe Petit ITODYS, Paris Diderot University Pascal Martin, Jean-Christophe Lacroix University of Alberta Richard L. McCreery Copenhagen, Quantum Wise TroelsMarkussen

  21. Let Us Meet Again We welcome all to our future group conferences of Omics group international Please visit: www.omicsgroup.com www.Conferenceseries.com http://optics.conferenceseries.com/

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