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Structural and electronic manipulation of fullerenes for use in molecular electronics
No full textThe work in this thesis focuses on how the properties of Buckminster Fullerene, C₆₀, and the related endohedral fullerene, Li@C₆₀, can be manipulated to alter their properties using Scanning Tunnelling Microscopy. The end goal of this is, eventually, for such molecules to be used to form functional electronic components.
Using lateral manipulation of isolated C₆₀ molecules on a Cu(111) surfaces, the distance dependence of superatom molecular orbital (SAMO) hybridisation between two fullerenes is demonstrated. The possibility of using the SAMOs to form artificial nearly-free electron (NFE) structures is then investigated. The electron transport properties of SAMOs are then investigated through tunnelling current induced molecular decomposition. When tunnelling through the SAMOs it is found that the molecules can withstand much greater currents than when electron transport occurs primarily through the lowest unoccupied molecular orbitals (LUMOs). Using this decomposition method the possibility of selectively patterning fullerene monolayers (and thus the delocalised SAMO states) is explored through the creation of an “artificial graphene” structure.
The endohedral fullerene, Li@C₆₀, and C₆₀ are investigated for use as molecular switches. A possible switching mechanism involving static Jahn-Teller (JT) distortions of the C₆₀ cage is proposed and the observed switched states assigned JT distortions with the aid of Hückel Molecular Orbital (HMO) theory simulated STM images. The thermally induced loss of lithium from Li@C₆₀ is investigated, in which Li@C₆₀ is converted to C₆₀ at high temperatures. This process is demonstrated to only occur in molecules at the perimeter of molecular islands with the rate of Li loss plateauing after several hours at high temperature
If you're so rational, why don't you have any friends? : a theory of doxastic wrongdoing and interpersonal rationality
Get PDFThis thesis is concerned with two key ideas. The first is doxastic wrongdoing, the idea that doxastic attitude could, in and of itself, constitute a wrong. The second is interpersonal rationality. A distinct sense of rationality applicable to both actions and beliefs that is to be contrasted against epistemic rationality. In exploring and elucidating these notions, I hope to make progress on issues facing contemporary social epistemologists. The thesis is split into two parts. In part one, we deal with doxastic wronging. In section 2, I motivate the idea that there are such things as doxastic wrongs. In section 3, I discuss how it is that belief could wrong by drawing on work done in Strawsonian Epistemology. In section 4, I then consider how the existence of doxastic wrongs impacts how we ought to reason. I suggest that doxastic wrongs impact what you ought to believe because they impact what is interpersonally rational.
The notion of interpersonal rationality on which I rely will be the focus of part two. In section 5, I clarify the notion further and consider what it is that the doxastic wrong theorist commits to in appealing to it. Sections 6 and 7 then consider objections to interpersonal rationality. In section 6, we consider an argument derived from the idea that interpersonal reasons, which bear on what is interpersonally rational, are reasons of the wrong kind. In section 7, we consider an argument which aims to show that interpersonal reasoning cannot occur as I have described. Having defended the notion, I then consider the work it can do in other areas of social epistemology, specifically for the doxastic partialist. In section 8, we will consider arguments for doxastic partiality. I argue that the partialist has much to gain from endorsing both the existence of doxastic wrongs and interpersonal rationality
HIP 41378 observed by CHEOPS : where is planet d?
Get PDFFunding: CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. CHEOPS data analysed in this article will be made available in the CHEOPS mission archive (https://cheops.unige.ch/archive_browser/). S.S. and M.D. acknowledge support from CNES, as well as the Programme National de Planétologie (PNP) of CNRS-INSU. L.B., G.B., V.N., I.P., G.P., R.R., G.S., V.S., and T.Z. acknowledge support from CHEOPS ASI-INAF agreement n. 2019-29-HH.0. This work has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. A.B. was supported by the SNSA. M.N.G. is the ESA CHEOPS Project Scientist and Mission Representative, and as such also responsible for the Guest Observers (GO) Programme. M.N.G. does not relay proprietary information between the GO and Guaranteed Time Observation (GTO) Programmes, and does not decide on the definition and target selection of the GTO Programme. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. M.F. and C.M.P. gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. Y.A. acknowledges support from the Swiss National Science Foundation (SNSF) under grant 200020_192038. We acknowledge financial support from the Agencia Estatal de Investigación of the Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033 and the ERDF “A way of making Europe” through projects PID2019-107061GB-C61, PID2019- 107061GB-C66, PID2021-125627OB-C31, and PID2021-125627OB-C32, from the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrofísica de Canarias (CEX2019-000920-S), from the Centre of Excellence “María de Maeztu” award to the Institut de Ciències de l’Espai (CEX2020-001058-M), and from the Generalitat de Catalunya/CERCA programme. We acknowledge financial support from the Agencia Estatal de Investigación of the Ministerio de Ciencia e Innovaciøn MCIN ´ /AEI/10.13039/501100011033 and the ERDF “A way of making Europe” through projects PID2019-107061GB-C61, PID2019- 107061GB-C66, PID2021-125627OB-C31, and PID2021-125627OB-C32, from the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrofísica de Canarias (CEX2019-000920-S), from the Centre of Excellence “María de Maeztu” award to the Institut de Ciències de l’Espai (CEX2020-001058-M), and from the Generalitat de Catalunya/CERCA programme. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. C.B. acknowledges support from the Swiss Space Office through the ESA PRODEX program. A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. A.C.M.C. ackowledges support from the FCT, Portugal, through the CFisUC projects UIDB/04564/2020 and UIDP/04564/2020, with DOI identifiers 10.54499/UIDB/04564/2020 and 10.54499/UIDP/04564/2020, respectively. P.E.C. is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. This project was supported by the CNES. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liège through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. L.D. thanks the Belgian Federal Science Policy Office (BELSPO) for the provision of financial support in the framework of the PRODEX Programme of the European Space Agency (ESA) under contract number 4000142531. This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 through the research grants UIDB/04434/2020, UIDP/04434/2020, 2022.06962.PTDC. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. B.-O.D. acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. This project has received funding from the Swiss National Science Foundation for project 200021_200726. It has also been carried out within the framework of the National Centre of Competence in Research PlanetS supported by the Swiss National Science Foundation under grant 51NF40_205606. The authors acknowledge the financial support of the SNSF. M.G. is an F.R.S.-FNRS Senior Research Associate. Ch.H. acknowledges support from the European Union H2020-MSCA-ITN-2019 under Grant Agreement no. 860470 (CHAMELEON). S.H. gratefully acknowledges CNES funding through the grant 837319. J.K. gratefully acknowledges the support of the Swedish Research Council (VR: Etableringsbidrag 2017-04945). A.C., A.D., B.E., K.G., and J.K. acknowledge their role as ESA-appointed CHEOPS Science Team Members. K.W.F.L. was supported by Deutsche Forschungsgemeinschaft grants RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche. P.M. acknowledges support from STFC research grant number ST/R000638/1. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). N.C.S. acknowledges funding by the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. A.S. acknowledges support from the Swiss Space Office through the ESA PRODEX program. S.G.S. acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). The Portuguese team thanks the Portuguese Space Agency for the provision of financial support in the framework of the PRODEX Programme of the European Space Agency (ESA) under contract number 4000142255. Gy.M.S. acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a PRODEX Experiment Agreement No. 4000137122, the Lendulet LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. V.V.G. is an F.R.S.-FNRS Research Associate. J.V. acknowledges support from the Swiss National Science Foundation (SNSF) under grant PZ00P2_208945. N.A.W. acknowledges UKSA grant ST/R004838/1. T.W. acknowledges support from the UKSA and the University of Warwick.HIP 41378 d is a long-period planet that has only been observed to transit twice, three years apart, with K2. According to stability considerations and a partial detection of the Rossiter- McLaughlin effect, Pd = 278.36 d has been determined to be the most likely orbital period. We targeted HIP 41378 d with CHEOPS at the predicted transit timing based on Pd = 278.36 d, but the observations show no transit. We find that large (> 22.4 h) transit timing variations (TTVs) could explain this non-detection during the CHEOPS observation window. We also investigated the possibility of an incorrect orbital solution, which would have major implications for our knowledge of this system. If Pd ≠ 278.36 d, the periods that minimize the eccentricity would be 101.22 d and 371.14 d. The shortest orbital period will be tested by TESS, which will observe HIP 41378 in Sector 88 starting in January 2025. Our study shows the importance of a mission like CHEOPS, which today is the only mission able to make long observations (i.e., from space) to track the ephemeris of long-period planets possibly affected by large TTVs.Peer reviewe
Solid-state lithium metal batteries for electric vehicles : critical single cell level assessment of capacity and lithium necessity
Get PDFFunding: V. S. thanks the University of Calgary for the Postdoctoral Fellowship. V. T. thanks the University of St Andrews for the Chair in Energy and Faraday Institution, UK for the fellowship.In pursuing advanced clean energy storage technologies, all-solid-state Li metal batteries (ASSMBs) emerge as promising alternatives to conventional organic liquid electrolyte-based batteries due to their reduced flammability risks, increased energy densities, extended lifespan, and design flexibility. Here, we estimate lithium requirements per unit of energy, cathode loading, and the amount of electrolyte required at a single-layer cell level ASSMB utilizing garnet-type, NASICON-type, and sulfide solid electrolytes and LiNi0.8Mn0.1Co0.1O2 (NMC811), LiCoO2, and LiFePO4 cathodes for Li metal anode and in situ anode configurations. To enable advanced batteries suitable for long-range and fast-charging electric vehicles, the electrodes (anode and cathode) must achieve a practical areal capacity of at least 7 mAh cm-2 and support rapid charging rates of 4C (15 min). Furthermore, we also present the key requirements for mechanical properties and strategic design considerations in ASSMB architecture to effectively address the challenges posed by the volume expansion of the electrodes.Peer reviewe
Detailed cool star flare morphology with CHEOPS and TESS
Get PDFFunding: A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. P.M. acknowledges support from STFC research grant number ST/R000638/1. C.He. acknowledges support from the European Union H2020-MSCA-ITN-2019 under Grant Agreement no. 860470 (CHAMELEON). N.C.S. acknowledges funding by the European Union (ERC, FIERCE, 101052347). N.A.W. acknowledges UKSA grant ST/R004838/1. T.W. acknowledges support from the UKSA and the University of Warwick.Context. White-light stellar flares are proxies for some of the most energetic types of flares, but their triggering mechanism is still poorly understood. As they are associated with strong X and ultraviolet emission, their study is particularly relevant to estimate the amount of high-energy irradiation onto the atmospheres of exoplanets, especially those in their stars’ habitable zone. Aims. We used the high-cadence, high-photometric capabilities of the CHEOPS and TESS space telescopes to study the detailed morphology of white-light flares occurring in a sample of 130 late-K and M stars, and compared our findings with results obtained at a lower cadence. Methods. We employed dedicated software for the reduction of 3 s cadence CHEOPS data, and adopted the 20 s cadence TESS data reduced by their official processing pipeline. We developed an algorithm to separate multi-peak flare profiles into their components, in order to contrast them to those of single-peak, classical flares. We also exploited this tool to estimate amplitudes and periodicities in a small sample of quasi-periodic pulsation (QPP) candidates. Results. Complex flares represent a significant percentage (≳30%) of the detected outburst events. Our findings suggest that high-impulse flares are more frequent than suspected from lower-cadence data, so that the most impactful flux levels that hit close-in exoplanets might be more time-limited than expected. We found significant differences in the duration distributions of single and complex flare components, but not in their peak luminosity. A statistical analysis of the flare parameter distributions provides marginal support for their description with a log-normal instead of a power-law function, leaving the door open to several flare formation scenarios. We tentatively confirmed previous results about QPPs in high-cadence photometry, report the possible detection of a pre-flare dip, and did not find hints of photometric variability due to an undetected flare background. Conclusions. The high-cadence study of stellar hosts might be crucial to evaluate the impact of their flares on close-in exoplanets, as their impulsive phase emission might otherwise be incorrectly estimated. Future telescopes such as PLATO and Ariel, thanks to their high-cadence capability, will help in this respect. As the details of flare profiles and of the shape of their parameter distributions are made more accessible by continuing to increase the instrument precision and time resolution, the models used to interpret them and their role in star-planet interactions might need to be updated constantly.Peer reviewe
Quantum backreaction effect in optical solitons
Get PDFFunding: This work was supported in part by the Science and Technology Facilities Council through the UKRI Quantum Technologies for Fundamental Physics Program [Grant ST/T005866/1]. SB was supported by the National Research Foundation of Korea [Grant RS-2023-00247194].Optical solitons classically are stationary solutions of the nonlinear Schrödinger equation. We perform a quantum field theoretic treatment by quantising a linearised fluctuation field around the classical soliton solution which can be seen as providing a background spacetime for the field. The linearised fluctuation modifies the soliton background, which is often neglected, reminiscent of the nondepleted-pump approximation. Going beyond this approximation and by using a number-conserving Bogoliubov approach, we find unstable modes that grow as the soliton propagates. Eventually, these unstable modes induce a considerable (backreaction) effect in the soliton. We calculate the backreaction in the classical field fully analytically in the leading second order. The result is a quadratic local decrease of the soliton photon number in propagation due to the backreaction effect of the unstable mode. Provided the initial pulse is close to the classical soliton solution, the unstable mode contributions always become dominant. We also consider practical scenarios for observing this quantum-induced soliton distortion, in the spectral domain. The backreaction, which we expect to be present in bright and dark, discrete and continuous solitons and other nonlinear pulses plays an important role in future optical analogue gravity experiments, for soliton lasers, and optical communications.Peer reviewe
Composable constraint models for permutation enumeration
Get PDFConstraint programming (CP) is a powerful tool for modeling mathematical concepts and objects and finding both solutions or counter examples. One of the major strengths of CP is that problems can easily be combined or expanded. In this paper, we illustrate that this versatility makes CP an ideal tool for exploring problems in permutation patterns. We declaratively define permutation properties, permutation pattern avoidance and containment constraints using CP and show how this allows us to solve a wide range of problems. We show how this approach enables the arbitrary composition of these conditions, and also allows the easy addition of extra conditions. We demonstrate the effectiveness of our techniques by modelling the containment and avoidance of six permutation patterns, eight permutation properties and measuring five statistics on the resulting permutations. In addition to calculating properties and statistics for the generated permutations, we show that arbitrary additional constraints can also be easily and efficiently added. This approach enables mathematicians to investigate permutation pattern problems in a quick and efficient manner. We demonstrate the utility of constraint programming for permutation patterns by showing how we can easily and efficiently extend the known permutation counts for a conjecture involving the class of 1324 avoiding permutations. For this problem, we expand the enumeration of 1324-avoiding permutations with a fixed number of inversions to permutations of length 16 and show for the first time that in the enumeration there is a pattern occurring which follows a unique sequence on the Online Encyclopedia of Integer Sequences.Peer reviewe
The interaction of law and politics in norm implementation
Get PDFWe lack a compelling way to study what a state’s effort to implement a norm of international law tells us about its commitment to that norm. When gauging commitment, some scholars focus on how seriously states take legal obligations in their justifications of contested actions. Other scholars apply a higher bar, namely whether law causes compliance or behavioural change. While the focus on justificatory discourse risks seeing legal influence everywhere, the latter emphasis of causation risks setting the bar too high and overlooking other ways in which law can matter. I argue that for a richer understanding of the interaction of law and politics, we need to explore the grey zone between empty words and purposive action. I propose that we can infer a state’s degree of commitment by looking at the consistency and publicity of words and actions and the state’s engagement with the international community. Depending on whether a state’s discourse and behavior exhibit low or strong levels of commitment, we can then identify weak normative influence, strong normative influence, behavioural or discursive norm avoidance. I illustrate these four different kinds of normative influence on norm implementation with case studies
Frugal algorithm selection
Get PDFWhen solving decision and optimisation problems, many competing algorithms (model and solver choices) have complementary strengths. Typically, there is no single algorithm that works well for all instances of a problem. Automated algorithm selection has been shown to work very well for choosing a suitable algorithm for a given instance. However, the cost of training can be prohibitively large due to running candidate algorithms on a representative set of training instances. In this work, we explore reducing this cost by choosing a subset of the training instances on which to train. We approach this problem in three ways: using active learning to decide based on prediction uncertainty, augmenting the algorithm predictors with a timeout predictor, and collecting training data using a progressively increasing timeout. We evaluate combinations of these approaches on six datasets from ASLib and present the reduction in labelling cost achieved by each option
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