@article{14015,
  abstract     = {We advance high-harmonic spectroscopy to resolve molecular charge migration in time and space and simultaneously demonstrate extensive control over the process. A multidimensional approach enables us to reconstruct both quantum amplitudes and phases with a resolution of better than 100 attoseconds and to separately reconstruct field-free and laser- driven charge migration. Our techniques make charge migration in molecules measurable on the attosecond time scale and open new avenues for laser control of electronic primary processes.},
  author       = {Kraus, P M and Mignolet, B and Baykusheva, Denitsa Rangelova and Rupenyan, A and Horný, L and Penka, E F and Tolstikhin, O I and Schneider, J and Jensen, F and Madsen, L B and Bandrauk, A D and Remacle, F and Wörner, H J},
  issn         = {1742-6596},
  journal      = {Journal of Physics: Conference Series},
  keywords     = {General Physics and Astronomy},
  number       = {11},
  publisher    = {IOP Publishing},
  title        = {{Attosecond charge migration and its laser control}},
  doi          = {10.1088/1742-6596/635/11/112136},
  volume       = {635},
  year         = {2015},
}

@article{14016,
  abstract     = {All attosecond time-resolved measurements have so far relied on the use of intense near-infrared laser pulses. In particular, attosecond streaking, laser-induced electron diffraction and high-harmonic generation all make use of non-perturbative light–matter interactions. Remarkably, the effect of the strong laser field on the studied sample has often been neglected in previous studies. Here we use high-harmonic spectroscopy to measure laser-induced modifications of the electronic structure of molecules. We study high-harmonic spectra of spatially oriented CH3F and CH3Br as generic examples of polar polyatomic molecules. We accurately measure intensity ratios of even and odd-harmonic orders, and of the emission from aligned and unaligned molecules. We show that these robust observables reveal a substantial modification of the molecular electronic structure by the external laser field. Our insights offer new challenges and opportunities for a range of emerging strong-field attosecond spectroscopies.},
  author       = {Kraus, P. M. and Tolstikhin, O. I. and Baykusheva, Denitsa Rangelova and Rupenyan, A. and Schneider, J. and Bisgaard, C. Z. and Morishita, T. and Jensen, F. and Madsen, L. B. and Wörner, H. J.},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  keywords     = {General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary},
  publisher    = {Springer Nature},
  title        = {{Observation of laser-induced electronic structure in oriented polyatomic molecules}},
  doi          = {10.1038/ncomms8039},
  volume       = {6},
  year         = {2015},
}

@article{14017,
  abstract     = {The detection of electron motion and electronic wave-packet dynamics is one of the core goals of attosecond science. Recently, choosing the nitric oxide molecule as an example, we have introduced and demonstrated an experimental approach to measure coupled valence electronic and rotational wave packets using high-order-harmonic-generation (HHG) spectroscopy [Kraus et al., Phys. Rev. Lett. 111, 243005 (2013)]. A short outline of the theory to describe the combination of the pump and HHG probe process was published together with an extensive discussion of experimental results [Baykusheva et al., Faraday Discuss. 171, 113 (2014)]. The comparison of theory and experiment showed good agreement on a quantitative level. Here, we present the theory in detail, which is based on a generalized density-matrix approach that describes the pump process and the subsequent probing of the wave packets by a semiclassical quantitative rescattering approach. An in-depth analysis of the different Raman scattering contributions to the creation of the coupled rotational and electronic spin-orbit wave packets is made. We present results for parallel and perpendicular linear polarizations of the pump and probe laser pulses. Furthermore, an analysis of the combined rotational-electronic density matrix in terms of irreducible components is presented that facilitates interpretation of the results.},
  author       = {Zhang, Song Bin and Baykusheva, Denitsa Rangelova and Kraus, Peter M. and Wörner, Hans Jakob and Rohringer, Nina},
  issn         = {1094-1622},
  journal      = {Physical Review A},
  keywords     = {Atomic and Molecular Physics, and Optics},
  number       = {2},
  publisher    = {American Physical Society},
  title        = {{Theoretical study of molecular electronic and rotational coherences by high-order-harmonic generation}},
  doi          = {10.1103/physreva.91.023421},
  volume       = {91},
  year         = {2015},
}

@inproceedings{1424,
  abstract     = {We consider the problem of statistical computations with persistence diagrams, a summary representation of topological features in data. These diagrams encode persistent homology, a widely used invariant in topological data analysis. While several avenues towards a statistical treatment of the diagrams have been explored recently, we follow an alternative route that is motivated by the success of methods based on the embedding of probability measures into reproducing kernel Hilbert spaces. In fact, a positive definite kernel on persistence diagrams has recently been proposed, connecting persistent homology to popular kernel-based learning techniques such as support vector machines. However, important properties of that kernel enabling a principled use in the context of probability measure embeddings remain to be explored. Our contribution is to close this gap by proving universality of a variant of the original kernel, and to demonstrate its effective use in twosample hypothesis testing on synthetic as well as real-world data.},
  author       = {Kwitt, Roland and Huber, Stefan and Niethammer, Marc and Lin, Weili and Bauer, Ulrich},
  location     = {Montreal, Canada},
  pages        = {3070 -- 3078},
  publisher    = {Neural Information Processing Systems Foundation},
  title        = {{Statistical topological data analysis-A kernel perspective}},
  volume       = {28},
  year         = {2015},
}

@inproceedings{1425,
  abstract     = {In this work we aim at extending the theoretical foundations of lifelong learning. Previous work analyzing this scenario is based on the assumption that learning tasks are sampled i.i.d. from a task environment or limited to strongly constrained data distributions. Instead, we study two scenarios when lifelong learning is possible, even though the observed tasks do not form an i.i.d. sample: first, when they are sampled from the same environment, but possibly with dependencies, and second, when the task environment is allowed to change over time in a consistent way. In the first case we prove a PAC-Bayesian theorem that can be seen as a direct generalization of the analogous previous result for the i.i.d. case. For the second scenario we propose to learn an inductive bias in form of a transfer procedure. We present a generalization bound and show on a toy example how it can be used to identify a beneficial transfer algorithm.},
  author       = {Pentina, Anastasia and Lampert, Christoph},
  location     = {Montreal, Canada},
  pages        = {1540 -- 1548},
  publisher    = {Neural Information Processing Systems Foundation},
  title        = {{Lifelong learning with non-i.i.d. tasks}},
  volume       = {2015},
  year         = {2015},
}

@inproceedings{1430,
  abstract     = {Evolutionary algorithms (EAs) form a popular optimisation paradigm inspired by natural evolution. In recent years the field of evolutionary computation has developed a rigorous analytical theory to analyse their runtime on many illustrative problems. Here we apply this theory to a simple model of natural evolution. In the Strong Selection Weak Mutation (SSWM) evolutionary regime the time between occurrence of new mutations is much longer than the time it takes for a new beneficial mutation to take over the population. In this situation, the population only contains copies of one genotype and evolution can be modelled as a (1+1)-type process where the probability of accepting a new genotype (improvements or worsenings) depends on the change in fitness. We present an initial runtime analysis of SSWM, quantifying its performance for various parameters and investigating differences to the (1+1) EA. We show that SSWM can have a moderate advantage over the (1+1) EA at crossing fitness valleys and study an example where SSWM outperforms the (1+1) EA by taking advantage of information on the fitness gradient.},
  author       = {Paixao, Tiago and Sudholt, Dirk and Heredia, Jorge and Trubenova, Barbora},
  booktitle    = {Proceedings of the 2015 Annual Conference on Genetic and Evolutionary Computation},
  location     = {Madrid, Spain},
  pages        = {1455 -- 1462},
  publisher    = {ACM},
  title        = {{First steps towards a runtime comparison of natural and artificial evolution}},
  doi          = {10.1145/2739480.2754758},
  year         = {2015},
}

@article{14303,
  abstract     = {Scaffolded DNA origami enables the fabrication of a variety of complex nanostructures that promise utility in diverse fields of application, ranging from biosensing over advanced therapeutics to metamaterials. The broad applicability of DNA origami as a material beyond the level of proof-of-concept studies critically depends, among other factors, on the availability of large amounts of pure single-stranded scaffold DNA. Here, we present a method for the efficient production of M13 bacteriophage-derived genomic DNA using high-cell-density fermentation of Escherichia coli in stirred-tank bioreactors. We achieve phage titers of up to 1.6 × 1014 plaque-forming units per mL. Downstream processing yields up to 410 mg of high-quality single-stranded DNA per one liter reaction volume, thus upgrading DNA origami-based nanotechnology from the milligram to the gram scale.},
  author       = {Kick, B and Praetorius, Florian M and Dietz, H and Weuster-Botz, D},
  issn         = {1530-6992},
  journal      = {Nano Letters},
  number       = {7},
  pages        = {4672--4676},
  publisher    = {ACS Publications},
  title        = {{Efficient production of single-stranded phage DNA as scaffolds for DNA origami}},
  doi          = {10.1021/acs.nanolett.5b01461},
  volume       = {15},
  year         = {2015},
}

@misc{1473,
  abstract     = {In this paper we survey geometric and arithmetic techniques to study the cohomology of semiprojective hyperkähler manifolds including toric hyperkähler varieties, Nakajima quiver varieties and moduli spaces of Higgs bundles on Riemann surfaces. The resulting formulae for their Poincaré polynomials are combinatorial and representation theoretical in nature. In particular we will look at their Betti numbers and will establish some results and state some expectations on their asymptotic shape.},
  author       = {Tamas Hausel and Rodríguez Villegas, Fernando},
  booktitle    = {Asterisque},
  number       = {370},
  pages        = {113 -- 156},
  publisher    = {Societe Mathematique de France},
  title        = {{Cohomology of large semiprojective hyperkähler varieties}},
  volume       = {2015},
  year         = {2015},
}

@inproceedings{1474,
  abstract     = {Cryptographic access control offers selective access to encrypted data via a combination of key management and functionality-rich cryptographic schemes, such as attribute-based encryption. Using this approach, publicly available meta-data may inadvertently leak information on the access policy that is enforced by cryptography, which renders cryptographic access control unusable in settings where this information is highly sensitive. We begin to address this problem by presenting rigorous definitions for policy privacy in cryptographic access control. For concreteness we set our results in the model of Role-Based Access Control (RBAC), where we identify and formalize several different flavors of privacy, however, our framework should serve as inspiration for other models of access control. Based on our insights we propose a new system which significantly improves on the privacy properties of state-of-the-art constructions. Our design is based on a novel type of privacy-preserving attribute-based encryption, which we introduce and show how to instantiate. We present our results in the context of a cryptographic RBAC system by Ferrara et al. (CSF'13), which uses cryptography to control read access to files, while write access is still delegated to trusted monitors. We give an extension of the construction that permits cryptographic control over write access. Our construction assumes that key management uses out-of-band channels between the policy enforcer and the users but eliminates completely the need for monitoring read/write access to the data.},
  author       = {Ferrara, Anna and Fuchsbauer, Georg and Liu, Bin and Warinschi, Bogdan},
  location     = {Verona, Italy},
  pages        = {46--60},
  publisher    = {IEEE},
  title        = {{Policy privacy in cryptographic access control}},
  doi          = {10.1109/CSF.2015.11},
  year         = {2015},
}

@article{1788,
  abstract     = {We fabricate and characterize a microscale silicon opto-electromechanical system whose mechanical motion is coupled capacitively to an electrical circuit and optically via radiation pressure to a photonic crystal cavity. To achieve large electromechanical interaction strength, we implement an inverse shadow mask fabrication scheme which obtains capacitor gaps as small as 30 nm while maintaining a silicon surface quality necessary for minimizing optical loss. Using the sensitive optical read-out of the photonic crystal cavity, we characterize the linear and nonlinear capacitive coupling to the fundamental ωm=2π = 63 MHz in-plane flexural motion of the structure, showing that the large electromechanical coupling in such devices may be suitable for realizing efficient microwave-to-optical signal conversion.},
  author       = {Pitanti, Alessandro and Johannes Fink and Safavi-Naeini, Amir H and Hill, Jeff T and Lei, Chan U and Tredicucci, Alessandro and Painter, Oskar J},
  journal      = {Optics Express},
  number       = {3},
  pages        = {3196 -- 3208},
  publisher    = {Optical Society of America},
  title        = {{Strong opto-electro-mechanical coupling in a silicon photonic crystal cavity}},
  doi          = {10.1364/OE.23.003196},
  volume       = {23},
  year         = {2015},
}

@article{1789,
  abstract     = {Intellectual disability (ID) has an estimated prevalence of 2-3%. Due to its extreme heterogeneity, the genetic basis of ID remains elusive in many cases. Recently, whole exome sequencing (WES) studies revealed that a large proportion of sporadic cases are caused by de novo gene variants. To identify further genes involved in ID, we performed WES in 250 patients with unexplained ID and their unaffected parents and included exomes of 51 previously sequenced child-parents trios in the analysis. Exome analysis revealed de novo intragenic variants in SET domain-containing 5 (SETD5) in two patients. One patient carried a nonsense variant, and the other an 81 bp deletion located across a splice-donor site. Chromosomal microarray diagnostics further identified four de novo non-recurrent microdeletions encompassing SETD5. CRISPR/Cas9 mutation modelling of the two intragenic variants demonstrated nonsense-mediated decay of the resulting transcripts, pointing to a loss-of-function (LoF) and haploinsufficiency as the common disease-causing mechanism of intragenic SETD5 sequence variants and SETD5-containing microdeletions. In silico domain prediction of SETD5, a predicted SET domain-containing histone methyltransferase (HMT), substantiated the presence of a SET domain and identified a novel putative PHD domain, strengthening a functional link to well-known histone-modifying ID genes. All six patients presented with ID and certain facial dysmorphisms, suggesting that SETD5 sequence variants contribute substantially to the microdeletion 3p25.3 phenotype. The present report of two SETD5 LoF variants in 301 patients demonstrates a prevalence of 0.7% and thus SETD5 variants as a relatively frequent cause of ID.},
  author       = {Kuechler, Alma and Zink, Alexander and Wieland, Thomas and Lüdecke, Hermann and Cremer, Kirsten and Salviati, Leonardo and Magini, Pamela and Najafi, Kimia and Zweier, Christiane and Czeschik, Johanna and Aretz, Stefan and Endele, Sabine and Tamburrino, Federica and Pinato, Claudia and Clementi, Maurizio and Gundlach, Jasmin and Maylahn, Carina and Mazzanti, Laura and Wohlleber, Eva and Schwarzmayr, Thomas and Kariminejad, Roxana and Schlessinger, Avner and Wieczorek, Dagmar and Strom, Tim and Novarino, Gaia and Engels, Hartmut},
  journal      = {European Journal of Human Genetics},
  number       = {6},
  pages        = {753 -- 760},
  publisher    = {Nature Publishing Group},
  title        = {{Loss-of-function variants of SETD5 cause intellectual disability and the core phenotype of microdeletion 3p25.3 syndrome}},
  doi          = {10.1038/ejhg.2014.165},
  volume       = {23},
  year         = {2015},
}

@article{1793,
  abstract     = {We present a software platform for reconstructing and analyzing the growth of a plant root system from a time-series of 3D voxelized shapes. It aligns the shapes with each other, constructs a geometric graph representation together with the function that records the time of growth, and organizes the branches into a hierarchy that reflects the order of creation. The software includes the automatic computation of structural and dynamic traits for each root in the system enabling the quantification of growth on fine-scale. These are important advances in plant phenotyping with applications to the study of genetic and environmental influences on growth.},
  author       = {Symonova, Olga and Topp, Christopher and Edelsbrunner, Herbert},
  journal      = {PLoS One},
  number       = {6},
  publisher    = {Public Library of Science},
  title        = {{DynamicRoots: A software platform for the reconstruction and analysis of growing plant roots}},
  doi          = {10.1371/journal.pone.0127657},
  volume       = {10},
  year         = {2015},
}

@article{17965,
  abstract     = {We investigate bidirectional femtosecond charge transfer dynamics using the core–hole clock implementation of resonant photoemission spectroscopy from 4,4′-bipyridine molecular layers on three different surfaces: Au(111), epitaxial graphene on Ni(111), and graphene nanoribbons. We show that the lowest unoccupied molecular orbital (LUMO) of the molecule drops partially below the Fermi level upon core–hole creation in all systems, opening an additional decay channel for the core–hole, involving electron donation from substrate to the molecule. Furthermore, using the core–hole clock method, we find that the bidirectional charge transfer time between the substrate and the molecule is fastest on Au(111), with a 2 fs time, then around 4 fs for epitaxial graphene and slowest with graphene nanoribbon surface, taking around 10 fs. Finally, we provide evidence for fast phase decoherence of the core-excited LUMO* electron through an interaction with the substrate providing the first observation of such a fast bidirectional charge transfer across an organic/graphene interface.},
  author       = {Adak, Olgun and Kladnik, Gregor and Bavdek, Gregor and Cossaro, Albano and Morgante, Alberto and Cvetko, Dean and Venkataraman, Latha},
  issn         = {1530-6992},
  journal      = {Nano Letters},
  number       = {12},
  pages        = {8316--8321},
  publisher    = {American Chemical Society},
  title        = {{Ultrafast bidirectional charge transport and electron decoherence at molecule/surface interfaces: A comparison of gold, graphene, and graphene nanoribbon surfaces}},
  doi          = {10.1021/acs.nanolett.5b03962},
  volume       = {15},
  year         = {2015},
}

@article{17966,
  author       = {Strange, Mikkel and Solomon, Gemma C. and Venkataraman, Latha and Campos, Luis M.},
  issn         = {1530-6992},
  journal      = {Nano Letters},
  number       = {11},
  pages        = {7177--7178},
  publisher    = {American Chemical Society},
  title        = {{Reply to “Comment on ‘Breakdown of Interference Rules in Azulene, a Nonalternant Hydrocarbon’”}},
  doi          = {10.1021/acs.nanolett.5b04154},
  volume       = {15},
  year         = {2015},
}

@article{17967,
  abstract     = {We report a systematic computational search of molecular frameworks for intrinsic rectification of electron transport. The screening of molecular rectifiers includes 52 molecules and conformers spanning over 9 series of structural motifs. N-Phenylbenzamide is found to be a promising framework with both suitable conductance and rectification properties. A targeted screening performed on 30 additional derivatives and conformers of N-phenylbenzamide yielded enhanced rectification based on asymmetric functionalization. We demonstrate that electron-donating substituent groups that maintain an asymmetric distribution of charge in the dominant transport channel (e.g., HOMO) enhance rectification by raising the channel closer to the Fermi level. These findings are particularly valuable for the design of molecular assemblies that could ensure directionality of electron transport in a wide range of applications, from molecular electronics to catalytic reactions.},
  author       = {Ding, Wendu and Koepf, Matthieu and Koenigsmann, Christopher and Batra, Arunabh and Venkataraman, Latha and Negre, Christian F. A. and Brudvig, Gary W. and Crabtree, Robert H. and Schmuttenmaer, Charles A. and Batista, Victor S.},
  issn         = {1549-9626},
  journal      = {Journal of Chemical Theory and Computation},
  number       = {12},
  pages        = {5888--5896},
  publisher    = {American Chemical Society},
  title        = {{Computational design of intrinsic molecular rectifiers based on asymmetric functionalization of N-Phenylbenzamide}},
  doi          = {10.1021/acs.jctc.5b00823},
  volume       = {11},
  year         = {2015},
}

@article{17968,
  abstract     = {While the electrical conductivity of bulk-scale group 14 materials such as diamond carbon, silicon, and germanium is well understood, there is a gap in knowledge regarding the conductivity of these materials at the nano and molecular scales. Filling this gap is important because integrated circuits have shrunk so far that their active regions, which rely so heavily on silicon and germanium, begin to resemble ornate molecules rather than extended solids. Here we unveil a new approach for synthesizing atomically discrete wires of germanium and present the first conductance measurements of molecular germanium using a scanning tunneling microscope-based break-junction (STM-BJ) technique. Our findings show that germanium and silicon wires are nearly identical in conductivity at the molecular scale, and that both are much more conductive than aliphatic carbon. We demonstrate that the strong donor ability of C–Ge σ-bonds can be used to raise the energy of the anchor lone pair and increase conductance. Furthermore, the oligogermane wires behave as conductance switches that function through stereoelectronic logic. These devices can be trained to operate with a higher switching factor by repeatedly compressing and elongating the molecular junction.},
  author       = {Su, Timothy A. and Li, Haixing and Zhang, Vivian and Neupane, Madhav and Batra, Arunabh and Klausen, Rebekka S. and Kumar, Bharat and Steigerwald, Michael L. and Venkataraman, Latha and Nuckolls, Colin},
  issn         = {1520-5126},
  journal      = {Journal of the American Chemical Society},
  number       = {38},
  pages        = {12400--12405},
  publisher    = {American Chemical Society},
  title        = {{Single-molecule conductance in atomically precise Germanium wires}},
  doi          = {10.1021/jacs.5b08155},
  volume       = {137},
  year         = {2015},
}

@article{17969,
  abstract     = {Recent experiments have shown that transport properties of molecular-scale devices can be reversibly altered by the surrounding solvent. Here, we use a combination of first-principles calculations and experiment to explain this change in transport properties through a shift in the local electrostatic potential at the junction caused by nearby conducting and solvent molecules chemically bound to the electrodes. This effect is found to alter the conductance of 4,4′-bipyridine-gold junctions by more than 50%. Moreover, we develop a general electrostatic model that quantitatively relates the conductance and dipoles associated with the bound solvent and conducting molecules. Our work shows that solvent-induced effects can be used to control charge and energy transport at molecular-scale interfaces.},
  author       = {Kotiuga, Michele and Darancet, Pierre and Arroyo, Carlos R. and Venkataraman, Latha and Neaton, Jeffrey B.},
  issn         = {1530-6992},
  journal      = {Nano Letters},
  number       = {7},
  pages        = {4498--4503},
  publisher    = {American Chemical Society},
  title        = {{Adsorption-induced solvent-based electrostatic gating of charge transport through molecular junctions}},
  doi          = {10.1021/acs.nanolett.5b00990},
  volume       = {15},
  year         = {2015},
}

@article{17970,
  abstract     = {Charge transport properties of metal–molecule interfaces depend strongly on the character of molecule–electrode interactions. Although through-bond coupled systems have attracted the most attention, through-space coupling is important in molecular systems when, for example, through-bond coupling is suppressed due to quantum interference effects. To date, a probe that clearly distinguishes these two types of coupling has not yet been demonstrated. Here, we investigate the origin of flicker noise in single molecule junctions and demonstrate how the character of the molecule–electrode coupling influences the flicker noise behavior of single molecule junctions. Importantly, we find that flicker noise shows a power law dependence on conductance in all junctions studied with an exponent that can distinguish through-space and through-bond coupling. Our results provide a new and powerful tool for probing and understanding coupling at the metal-molecule interface.},
  author       = {Adak, Olgun and Rosenthal, Ethan and Meisner, Jeffery and Andrade, Erick F. and Pasupathy, Abhay N. and Nuckolls, Colin and Hybertsen, Mark S. and Venkataraman, Latha},
  issn         = {1530-6992},
  journal      = {Nano Letters},
  number       = {6},
  pages        = {4143--4149},
  publisher    = {American Chemical Society},
  title        = {{Flicker noise as a probe of electronic interaction at metal–single molecule interfaces}},
  doi          = {10.1021/acs.nanolett.5b01270},
  volume       = {15},
  year         = {2015},
}

@article{17971,
  abstract     = {We study the impact of electrode band structure on transport through single-molecule junctions by measuring the conductance of pyridine-based molecules using Ag and Au electrodes. Our experiments are carried out using the scanning tunneling microscope based break-junction technique and are supported by density functional theory based calculations. We find from both experiments and calculations that the coupling of the dominant transport orbital to the metal is stronger for Au-based junctions when compared with Ag-based junctions. We attribute this difference to relativistic effects, which result in an enhanced density of d-states at the Fermi energy for Au compared with Ag. We further show that the alignment of the conducting orbital relative to the Fermi level does not follow the work function difference between two metals and is different for conjugated and saturated systems. We thus demonstrate that the details of the molecular level alignment and electronic coupling in metal–organic interfaces do not follow simple rules but are rather the consequence of subtle local interactions.},
  author       = {Adak, Olgun and Korytár, Richard and Joe, Andrew Y. and Evers, Ferdinand and Venkataraman, Latha},
  issn         = {1530-6992},
  journal      = {Nano Letters},
  number       = {6},
  pages        = {3716--3722},
  publisher    = {American Chemical Society},
  title        = {{Impact of electrode density of states on transport through pyridine-linked single molecule junctions}},
  doi          = {10.1021/acs.nanolett.5b01195},
  volume       = {15},
  year         = {2015},
}

@article{17972,
  abstract     = {Molecular electronics aims to miniaturize electronic devices by using subnanometre-scale active components1,2,3. A single-molecule diode, a circuit element that directs current flow4, was first proposed more than 40 years ago5 and consisted of an asymmetric molecule comprising a donor–bridge–acceptor architecture to mimic a semiconductor p–n junction. Several single-molecule diodes have since been realized in junctions featuring asymmetric molecular backbones6,7,8, molecule–electrode linkers9 or electrode materials10. Despite these advances, molecular diodes have had limited potential for applications due to their low conductance, low rectification ratios, extreme sensitivity to the junction structure and high operating voltages7,8,9,11,12. Here, we demonstrate a powerful approach to induce current rectification in symmetric single-molecule junctions using two electrodes of the same metal, but breaking symmetry by exposing considerably different electrode areas to an ionic solution. This allows us to control the junction's electrostatic environment in an asymmetric fashion by simply changing the bias polarity. With this method, we reliably and reproducibly achieve rectification ratios in excess of 200 at voltages as low as 370 mV using a symmetric oligomer of thiophene-1,1-dioxide13,14. By taking advantage of the changes in the junction environment induced by the presence of an ionic solution, this method provides a general route for tuning nonlinear nanoscale device phenomena, which could potentially be applied in systems beyond single-molecule junctions.},
  author       = {Capozzi, Brian and Xia, Jianlong and Adak, Olgun and Dell, Emma J. and Liu, Zhen-Fei and Taylor, Jeffrey C. and Neaton, Jeffrey B. and Campos, Luis M. and Venkataraman, Latha},
  issn         = {1748-3395},
  journal      = {Nature Nanotechnology},
  number       = {6},
  pages        = {522--527},
  publisher    = {Springer Nature},
  title        = {{Single-molecule diodes with high rectification ratios through environmental control}},
  doi          = {10.1038/nnano.2015.97},
  volume       = {10},
  year         = {2015},
}

