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The Joint European Torus (JET) has recently conducted its second deuterium-tritium (DT) experimental campaign DTE2, providing unique opportunity for studying both physics and engineering aspects of nuclear fusion plasmas. This also allowed the exploitation of new diagnostics and technologies that were not available during the first JET DT campaign held in 1997. Among these new instruments, the enhancement projects of the JET nuclear diagnostics lead to the development and installation of synthetic single crystal diamond detectors along different collimated line of sights. This paper describes the single crystal diamond-based diagnostic suite of the JET tokamak and the enhanced 14 MeV neutron diagnostic capabilities in terms of neutron yield and high resolution neutron spectroscopy. The diamond characterization measurements and the calibration procedure at JET are shown, together with performance of the diamond based neutron spectrometer as 14 MeV neutron yield monitor which allows the separation of 2.5 MeV and 14 MeV neutrons in trace tritium plasmas. The first high-resolution 14 MeV neutron spectroscopy measurements in neutral beam injection-heated DT plasmas are presented, allowing thermal and non-thermal neutron component separation. Prospects for the diagnose of DT burning plasmas such as ITER and SPARC will be presented.

In the last decades, nanostructures have unlocked myriads of functionalities in nanophotonics by engineering light–matter interaction beyond what is possible with conventional bulk optics. The space of parameters available for design is practically unlimited due to the large variety of optical materials and nanofabrication techniques. Thus, computational approaches are necessary to efficiently search for the optimal solutions. In this paper, we enable the free-form inverse design in 3D of linear optical materials with arbitrary dispersion and anisotropy. This is achieved by (1) deriving an analytical adjoint scheme based on the complex-conjugate pole-residue pair model in the time domain and (2) its implementation in a parallel finite-difference time-domain framework with a topology optimization routine, efficiently running on high-performance computing systems. Our method is tested on the design problem of field confinement using dispersive nanostructures. The obtained designs satisfy the fundamental curiosity of how free-form metallic and dielectric nanostructures perform when optimized in 3D, also in comparison to fabrication-constrained designs. Unconventional free-form designs revealed by computational methods, although may be challenging or unfeasible to realize with current technology, bring new insights into how light can more efficiently interact with nanostructures and provide new ideas for forward design.

A unified description of physical phenomena through measurement science is one of the foundational pillars in a global society. The International System of Units (SI) is the most widely used system of units and since its redefinition in 2019, all units encompassed by it are based on fundamental physical constants. The units of the SI, such as the second, metre, and kilogram, are realized by the use of primary standards which are used, through calibration chains, to certify the accuracy of measuring devices in our society. Its redefinition enabled the realization of the SI-unit for pressure (pascal) in a novel way; instead of force per area (N/m2), it can alternatively be defined as an energy density (J/m3). Subsequently, this opened up for the use of optical realizations of the pascal (Pa). It has been prophesied that a possible means to do this is by assessing refractivity through the use of Fabry-Pérot (FP) refractometry. Although such instrumentation indeed can assess refractivity, it has unfortunately been found that they in practice are affected by various types of disturbances that aggravate assessments with the required uncertainty. This thesis describes the development of FP-based refractometers utilizing a novel measurement methodology, denoted gas modulation refractometry (GAMOR). By the use of rapid gas modulation and baseline interpolation, GAMOR has the ability to significantly reduce the influence of various types of disturbances, not least drifts and fluctuations. From this, two FP-based refractometers have been developed; one stationary, denoted the SOP, capable of assessing pressure with an uncertainty of [(10 mPa)2 + (10 × 10−6·P)2]1/2, and one transportable, denoted the TOP, with an uncertainty of [(16 mPa)2 + (28 × 10−6·P)2]1/2. Furthermore, it was shown that their mutual short-term precision is excellent, with a deviation of only 0.04 ppm when simultaneously assessing a pressure of 16 kPa. A major part of this thesis was devoted to the construct, En av grundpelarna i ett globalt samhälle är en enad syn på fysikaliska fenomen med förankring i vetenskap. Det Internationella måttenhetssystemet (SI) är det mest använda enhetssystemet och sedan dess omdefiniering 2019 är alla dess enheter baserade på grundläggande fysikaliska konstanter. SI-enheterna, som exempelvis sekund, meter och kilogram, realiseras genom primära standarder. Dessa standarder används, via kalibreringskedjor, för att certifiera noggrannheten av mätinstrument runtom vårt samhälle. Omdefiniering ledde till möjligheten att realisera enheten för tryck (pascal) på ett nytt sätt; i stället för kraft per area (N/m2) går det numera att definiera tryck som energidensitet (J/m3). Detta ledde i sin tur till att optiska realiseringar av pascal (Pa) för gastryck blev en möjlighet. Det har påvisats att detta kan uppnås genom att mäta refraktivitet med hjälp av Fabry-Pérot (FP)-refraktometri. Även om denna teknik kan användas för att bestämma refraktivitet, påverkas den i praktiken av diverse störningar vilket försvårar den nogrannhet som krävs för att ersätta dagens mekaniska tryckstandarder. I denna avhandling beskrivs utvecklingen av FP-baserade refraktometrar som använder sig av en av oss nyutvecklad mätteknik; gasmodulationsrefraktometri (GAMOR). Tekniken bygger på en snabb modulering av gas och baslinje-interpolering, vilket reducerar effekten av snabba likaväl som långsamma störningar. Baserat på detta har två refraktometrar utvecklats; en stationär, SOP, som kan mäta tryck med en osäkerhet på [(10 mPa)2 + (10 × 10−6·P)2]1/2, samt en transportabel, TOP, med en osäkerhet på [(16 mPa)2 + (28 × 10−6·P)2]1/2. Vidare har det visats att deras inbördes korttidsprecision är utmärkt, med en avvikelse på endast 0.04 ppm när de samtidigt mätte ett tryck på 16 kPa. En signifikant del av denna avhandling har ägnats till att konstruera TOP:en, samt att undersöka dess transporterbarhet och prestanda. Den användes i en serie jämförelsemätningar av olika tryckstandard

Non-fullerene electron acceptors have emerged as promising alternatives to traditional electron-acceptors in the active layers of organic photovoltaics. This is due to their tunable energy levels, optical response in the visible light spectrum, high electron mobility, and photochemical stability. In this study, the electronic properties of two representative non-fullerene acceptors, ITIC and Y5, have been calculated within the framework of density functional theory using a range of hybrid and non-hybrid density functionals. Screened range-separated hybrid (SRSH) approaches were also tested. The results are analyzed in light of the previously reported experimental outcomes. Specifically, we have calculated the oxidation and reduction potentials, fundamental and optical gaps, the highest occupied molecular orbital and lowest unoccupied molecular orbital energies, and exciton binding energies. Additionally, we have investigated the effects of the medium dielectric constant on these properties employing a universal implicit solvent model. It was found that hybrid functionals generally perform poorly in predicting oxidation potentials, while non-hybrid functionals tend to overestimate reduction potentials. The inclusion of a large Hartree-Fock contribution to the global or long range was identified as the source of inaccuracy for many hybrid functionals in predicting both redox potentials and the fundamental and optical gaps. Corroborating with the available literature, ∼50% of all tested functionals predicted very small exciton binding energies, within the range of ±0.1 eV, that become even smaller by increasing the dielectric constant of the material. Finally, the OHSE2PBE and tHCTHhyb functionals and the optimal tuning SRSH approach emerged as the best-performing methods, with good accuracy in the description of the electronic properties of interest.

Circularly polarized light (CPL) is widely used for various applications in sensing and imaging(1-3). An ongoing challenge is to realize high-quality CPL detection using chiral organic semiconductors, especially in the near-infrared (NIR) region(4). Chiral molecules tend to rely on twisted stereogenic moieties; however, conventional approaches to reduce the bandgap of organic semiconductors are based on the use of co-planar backbones that commonly lead to molecular symmetries preventing chirality. Here we report a widely applicable strategy to directly induce chiroptical activity in planar non-fullerene acceptors(5-7), which are widely used for high-performance organic photovoltaics and provide a wealth of opportunities to fill the spectral gap of CPL detection in the NIR regime. We demonstrate proof-of-concept circularly polarized organic photodiodes using chiroptically active non-fullerene acceptor blends, which exhibit strong circular dichroism and hence great sensitivity to CPL in the NIR region. Importantly, this strategy is found to be effective in a wide series of state-of-the-art non-fullerene acceptor families including ITIC5, o-IDTBR6 and Y6 analogues(7), which substantially broadens the range of materials applicable to NIR CPL detection., Funding Agencies|Knut and Alice Wallenberg Foundation [KAW 2019.0082]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Stiftelsen for Strategisk Forskning through a Future Research Leader programme [FFL18-0322]; Office of Naval Research [N00014-20-1-2110]; UA College of Science; Linkoping University

The frequency of reports utilizing synchrotron-based grazing incident wide angle X-ray scattering (GIWAXS) to study metal halide perovskite thin films has exploded recently, as this technique has proven invaluable for understanding several structure-property relationships that fundamentally limit optoelectronic performance. The GIWAXS geometry and temporal resolution are also inherently compatible with in situ and operando setups (including ISOS protocols), and a relatively large halide perovskite research community has deployed GIWAXS to unravel important kinetic and dynamic features in these materials. Considering its rising popularity, the aim here is to accelerate the required learning curve for new experimentalists by clearly detailing the underlying analytical concepts which can be leveraged to maximize GIWAXS studies of polycrystalline thin films and devices. Motivated by the vast range of measurement conditions offered, together with the wide variety of compositions and structural motifs available (i.e., from single-crystal and polycrystalline systems, to quantum dots and layered superlatices), a comprehensive framework for conducting effective GIWAXS experiments is outlined for different purposes. It is anticipated that providing a clear perspective for this topic will help elevate the quality of future GIWAXS studies-which have become routine-and provide the impetus required to develop novel GIWAXS approaches to resolve unsettled scientific questions., Funding Agencies|Research Foundation - Flanders [FWO] [1242922N, 12Y7221N, V400622N]; FWO through research projects [G098319N, G0A5923N, S002019N, S004322N, ZW15_09-GOH6316]; KU Leuven Research fund [Meth/15/04]; Flemish government [CASAS2]; KU Leuven Industrial Research Fund [C3/19/046]; U.S. Department of Energy (DOE) Solar Energy Technology Office (SETO) of Energy Efficiency and Renewable Energy (EERE) award; Australian Research Council [FL190100139, DP230100621, FT210100589, DP230101901, DE230101712, DE230100173]; Centre for Microscopy and Microanalysis (CMM); Australian National Fabrication Facility (ANFF), University of Queensland; University of Queenslands Knowledge Exchange and Translation Fund Award; Swedish Energy Agency [46564-1]; [iBOF-21-085]

In organic solar cells with very small energetic-offset (& UDelta;ELE - CT), the charge-transfer (CT) and local-exciton (LE) states strongly interact via electronic hybridization and thermal population effects, suppressing the non-radiative recombination. Here, we investigated the impact of these effects on charge generation and recombination. In the blends of PTO2:C8IC and PTO2:Y6 with very small, ultra-fast CT state formation was observed, and assigned to direct photoexcitation resulting from strong hybridization of the LE and CT states (i.e., LE-CT intermixed states). These states in turn accelerate the recombination of both CT and charge separated (CS) states. Moreover, they can be significantly weakened by an external-electric field, which enhanced the yield of CT and CS states but attenuated the emission of the device. This study highlights that excessive LE-CT hybridization due to very low , whilst enabling direct and ultrafast charge transfer and increasing the proportion of radiative versus non-radiative recombination rates, comes at the expense of accelerating recombination losses competing with exciton-to-charge conversion process, resulting in a loss of photocurrent generation., Funding Agencies|Swedish Research Council VR [2019-00677]; National Natural Science Foundation of China (NSFC) [51973146]; Shandong Provincial Natural Science Foundation [ZR2022JQ09]; Collaborative Innovation Center of Suzhou Nano Science amp; Technology; EPSRC project ATIP [EP/TO28513/1]; Office of Naval Research [N00014-20-1-2110]

True random number generation is not thought to be possible using a classical approach but by instead exploiting quantum mechanics genuine randomness can be achieved. Here, the authors demonstrate a certified quantum random number generation using a metal-halide perovskite light emitting diode as a source of weak coherent polarisation states randomly producing an output of either 0 or 1. The recent development of perovskite light emitting diodes (PeLEDs) has the potential to revolutionize the fields of optical communication and lighting devices, due to their simplicity of fabrication and outstanding optical properties. Here we demonstrate that PeLEDs can also be used in the field of quantum technologies by implementing a highly-secure quantum random number generator (QRNG). Modern QRNGs that certify their privacy are posed to replace classical random number generators in applications such as encryption and gambling, and therefore need to be cheap, fast and with integration capabilities. Using a compact metal-halide PeLED source, we generate random numbers, which are certified to be secure against an eavesdropper, following the quantum measurement-device-independent scenario. The obtained generation rate of more than 10 Mbit s(-1), which is already comparable to commercial devices, shows that PeLEDs can work as high-quality light sources for quantum information tasks, thus opening up future applications in quantum technologies., Funding: CENIIT Linkouml;ping University; Swedish Research Council [2017-04470]; QuantERA grant SECRET [2019-00392]; Knut and Alice Wallenberg Foundation through the Wallenberg Centre for Quantum Technology (WACQT); ERC Starting Grant [717026]; Wallenberg Academy Fellowship; Fondo Nacional de Desarrollo Cientifico y Tecnologico (FONDECYT) [1200859]; ANID-Millennium Science Initiative Program [ICN17_012]; Linkoeping University

The geometrical structure and photoexcitation properties of Zn27-nCdnO27C42 complexes are investigated by density functional theory (DFT) and time-dependent DFT calculations at the PBE0/6-31G*/SDD level of theory. The cohesive energy and frequency analysis indicate that the hybrid materials are energetically stable. In presence of Cd substituting atoms, the energy gap of the ZnO nanodots surrounded by carbon moiety is shown to decrease, as compared to Cd-free complex. In-depth excited state analysis including charge density difference (CDD) mapping and absorption spectrum decomposition is performed to reveal the nature of the dominant excited states and to comprehend the Cd-to-Zn substitution effect on the photoexcitation properties of Zn27-nCdnO27C42. A principal possibility to enhance the intramolecular charge transfer through incorporation of certain number of Cd atoms into the ZnO nanodots is shown. Such Cd-induced modifications in optical properties of semi-spherical Zn27-nCdnO27C42 complexes could potentially enable use of this hybrid material in optoelectronic and photocatalytic applications., Funding Agencies|Aforsk [21-112]

The multifunctional materials for application in organic light-emitting devices (OLEDs) based on a single structural motif are very desired but quite rare species. Such structures allow simplifying the chemical variety within OLED heterostructures and thus reducing their cost, manufacturing time, and logistic efforts. In this paper, we report the 9-(2,3,5,6-tetrafluoro-4-vinylphenyl)carbazole molecule (Cz4FS) utilized as a fluorescent emitter, host material for quantum dot based OLEDs (QLEDs), acceptor part of the exciplex active layer, and monomer that can be used for the preparation of emissive polymers and copolymers. The external quantum efficiency (EQE) of the corresponding fluorescent OLED based on a Cz4FS single emitter doped into a 1,3-bis(carbazol-9-yl)benzene matrix is 4.2%, which is close to the theoretical limit and maximum brightness at the level of 3600 cd/m2. An OLED based on exciplex emission obtained utilizing Cz4FS as an acceptor demonstrates higher efficiency (5.3%) and much higher brightness near 25 000 cd/m2. A QLED based on Cz4FS as a host for CdSeS/ZnS core-shell quantum dots demonstrates excellent energy transfer from the Cz4FS matrix that results in a clear spectrum of quantum dots with an EQE of 2.3%, maximum of 19 000 cd/m2, and narrow spectral distribution. An OLED based on a Cz4FS-based polymer and copolymer demonstrates not extraordinary efficiency but low-efficiency roll-off in a wide range of current densities., Funding Agencies|Swedish Research Council [2022-06725]; Carl Tryggers Stiftelse (Sweden) [CTS 21:1430]; Ministry of Education and Science of Ukraine [0121U107533, 0121U109506, NAISS 2023/5-77]; Research Council of Lithuania (LMTLT) [S-MIP-22-78]

Non-fullerene electron acceptors have emerged as promising alternatives to traditional electron-acceptors in the active layers of organic photovoltaics. This is due to their tunable energy levels, optical response in the visible light spectrum, high electron mobility, and photochemical stability. In this study, the electronic properties of two representative non-fullerene acceptors, ITIC and Y5, have been calculated within the framework of density functional theory using a range of hybrid and non-hybrid density functionals. Screened range-separated hybrid (SRSH) approaches were also tested. The results are analyzed in light of the previously reported experimental outcomes. Specifically, we have calculated the oxidation and reduction potentials, fundamental and optical gaps, the highest occupied molecular orbital and lowest unoccupied molecular orbital energies, and exciton binding energies. Additionally, we have investigated the effects of the medium dielectric constant on these properties employing a universal implicit solvent model. It was found that hybrid functionals generally perform poorly in predicting oxidation potentials, while non-hybrid functionals tend to overestimate reduction potentials. The inclusion of a large Hartree-Fock contribution to the global or long range was identified as the source of inaccuracy for many hybrid functionals in predicting both redox potentials and the fundamental and optical gaps. Corroborating with the available literature, ∼50% of all tested functionals predicted very small exciton binding energies, within the range of ±0.1 eV, that become even smaller by increasing the dielectric constant of the material. Finally, the OHSE2PBE and tHCTHhyb functionals and the optimal tuning SRSH approach emerged as the best-performing methods, with good accuracy in the description of the electronic properties of interest.

Experimental studies indicate that optical cavities can affect chemical reactions through either vibrational or electronic strong coupling and the quantized cavity modes. However, the current understanding of the interplay between molecules and confined light modes is incomplete. Accurate theoretical models that take into account intermolecular interactions to describe ensembles are therefore essential to understand the mechanisms governing polaritonic chemistry. We present an ab initio Hartree–Fock ansatz in the framework of the cavity Born–Oppenheimer approximation and study molecules strongly interacting with an optical cavity. This ansatz provides a nonperturbative, self-consistent description of strongly coupled molecular ensembles, taking into account the cavity-mediated dipole self-energy contributions. To demonstrate the capability of the cavity Born–Oppenheimer Hartree–Fock ansatz, we study the collective effects in ensembles of strongly coupled diatomic hydrogen fluoride molecules. Our results highlight the importance of the cavity-mediated intermolecular dipole–dipole interactions, which lead to energetic changes of individual molecules in the coupled ensemble.

QC 20231025

In photovoltaics, the cover glass module has hitherto not yet been fully optimized for its purpose. Instead quite conventional architectural glass is used. In a recent review of the state-of-the-art on UV down converting dopants [1], a way forward to improve cover glasses was presented. Some of these possibilities, and others are covered in the present paper. We present possibilities to add several functionalities, instead of using dopants in the glass composition, including omnidirectional antireflection, dynamic solar control, and self-cleaning. Omni-directional anti-reflective coatings, were made by colloidal lithography templating methods on iron free glass, realizing nanopillar structures with dimensions /2 exploiting Mie scattering for wide angle light collection (Fig. 1). Yttrium oxyhydride (YHO) coatings were deposited on the nanopillar structures using magnetron sputtering methods [2]. The YHO film blocks UV light and photo-darkens upon solar light absorption and reverts to its transparent state in dark in reproducible manner [2]. In addition, the YHO film also becomes hydrophobic upon photo-darkening, acting as a self-cleaning layer. The fabricated coatings were compared with bare glass substrates. The results reveal suppressed reflectance, with acceptable anti-reflective properties up to about 50 degrees. Solar light modulation of a thin 100 nm YHO coating is below 10% thus having high transmittance throughput while allowing for solar cell life-time saving by removal of excess irradiance. Finally, the surface energy of the YHO coated glass structures are presented, demonstrating synergetic chemical and structural (the Lotus effect), showing promising self-cleaning properties. In conclusion, we show possibilities to combine photonic and chromogenic principles with suitable surface chemistry to achieve high-performance cover glass for solar energy application. ., Funding: Energimyndigheten P2022-00859, Transparenta multifunktionella tunnfilmer på lågjärnglas för solcellsapplikationer, Semi-transparent solcells- och fotokromt smart fönster

Renewed enthusiasm for space exploration brings more ambitious missions to light butthe constraints of chemical rockets put imposing limits on what is feasible. Nuclearthermal rockets provide an attractive and efficient alternative to shorten travel timesand increase payload. In this thesis, a dynamic model of a Nuclear thermal rocketengine is derived in order to simulate the resulting performance of the engine. Thework is inspired by a similar model on the Space Shuttle Main Engine (SSME).

QC 20231025

The evolution of vector solitons under nonlinearity management is studied. The averaged over strong and rapid modulations in time of the inter-species interactions vector Gross-Pitaevskii equation (GPE) is derived. The averaging gives the appearance of the effective nonlinear quantum pressure depending on the population of the other component. Using this system of equations, the existence and stability of the vector solitons under the action of the strong nonlinearity management (NM) is investigated. Using a variational approach the parameters of NM vector solitons are found. The numerical simulations of the full time-dependent coupled GPE confirms the theoretical predictions.

We investigate the rotational properties of a two-component, two-dimensional self-bound quantum droplet, which is confined in a harmonic potential and compare them with the well-known problem of a single-component atomic gas with contact interactions. For a fixed value of the trap frequency, choosing some representative values of the atom number, we determine the lowest-energy state, as the angular momentum increases. For a sufficiently small number of atoms, the angular momentum is carried via center-of-mass excitation. For larger values, when the angular momentum is sufficiently small, we observe vortex excitation instead. Depending on the actual atom number, one or more vortices enter the droplet. Beyond some critical value of the angular momentum, however, the droplet does not accommodate more vortices and the additional angular momentum is carried via center-of-mass excitation in a "mixed" state. Finally, the excitation spectrum is also briefly discussed.

Integrating different reaction sites offers new prospects to address the difficulties in single-atom catalysis, but the precise regulation of active sites at the atomic level remains challenging. Here, we demonstrate a sodium-directed photon-induced assembly (SPA) strategy for boosting the atomic utilization efficiency of single-atom catalysts (SACs) by constructing multifarious Au sites on TiO2 substrate. Na+ was employed as the crucial cement to direct Au single atoms onto TiO2, while the light-induced electron transfer from excited TiO2 to Au(Na+) ensembles contributed to the self-assembly formation of Au nanoclusters. The synergism between plasmonic near-field and Schottky junction enabled the cascade electron transfer for charge separation, which was further enhanced by oxygen vacancies in TiO2. Our dual-site photocatalysts exhibited a nearly 2 orders of magnitude improvement in the hydrogen evolution activity under simulated solar light, with a striking turnover frequency (TOF) value of 1533 h(-1) that exceeded other Au/TiO2-based photocatalysts reported. Our SPA strategy can be easily extended to prepare a wide range of metal-coupled nanostructures with enhanced performance for diverse catalytic reactions. Thus, this study provides a well-defined platform to extend the boundaries of SACs for multisite catalysis through harnessing metal-support interactions., Funding Agencies|National Natural Science Foundation of China [51978372, 52225308, 11974037, 52202099]; UK EPSRC [EP/S018204/2]; Leverhulme Trust [RPG-2017-122]; Royal Society Newton Advanced Fellowship grant [NAF\R1\191163]; Royal Society Leverhulme Trust [SRF\R1\21000153]

We investigate the impact of chirped driving fields on the dynamics and generation of Kerr cavity breathers and solitons. Synchronous phase and amplitude modulation of the pumping field can be exploited in order to control soliton dynamics. Here we show that using a phase-modulated super-Gaussian pump permits to stabilize the oscillations of breathing solitons. Moreover, our scheme permits to obtain new dynamical attractors, with a prescribed temporal intra-cavity pattern. Straightforward applications are the deterministic generation of optical frequency soliton combs, optical tweezers, and more generally, all-optical manipulation of light pulses., Funding: ADD Sapiexcellence 2022 grant; Marie Sklodowska-Curie Actions; Olle Engkvist Foundation [101023717]; [214-0328]; [101064614]

In organic solar cells with very small energetic-offset (& UDelta;ELE - CT), the charge-transfer (CT) and local-exciton (LE) states strongly interact via electronic hybridization and thermal population effects, suppressing the non-radiative recombination. Here, we investigated the impact of these effects on charge generation and recombination. In the blends of PTO2:C8IC and PTO2:Y6 with very small, ultra-fast CT state formation was observed, and assigned to direct photoexcitation resulting from strong hybridization of the LE and CT states (i.e., LE-CT intermixed states). These states in turn accelerate the recombination of both CT and charge separated (CS) states. Moreover, they can be significantly weakened by an external-electric field, which enhanced the yield of CT and CS states but attenuated the emission of the device. This study highlights that excessive LE-CT hybridization due to very low , whilst enabling direct and ultrafast charge transfer and increasing the proportion of radiative versus non-radiative recombination rates, comes at the expense of accelerating recombination losses competing with exciton-to-charge conversion process, resulting in a loss of photocurrent generation., Funding Agencies|Swedish Research Council VR [2019-00677]; National Natural Science Foundation of China (NSFC) [51973146]; Shandong Provincial Natural Science Foundation [ZR2022JQ09]; Collaborative Innovation Center of Suzhou Nano Science amp; Technology; EPSRC project ATIP [EP/TO28513/1]; Office of Naval Research [N00014-20-1-2110]

True random number generation is not thought to be possible using a classical approach but by instead exploiting quantum mechanics genuine randomness can be achieved. Here, the authors demonstrate a certified quantum random number generation using a metal-halide perovskite light emitting diode as a source of weak coherent polarisation states randomly producing an output of either 0 or 1. The recent development of perovskite light emitting diodes (PeLEDs) has the potential to revolutionize the fields of optical communication and lighting devices, due to their simplicity of fabrication and outstanding optical properties. Here we demonstrate that PeLEDs can also be used in the field of quantum technologies by implementing a highly-secure quantum random number generator (QRNG). Modern QRNGs that certify their privacy are posed to replace classical random number generators in applications such as encryption and gambling, and therefore need to be cheap, fast and with integration capabilities. Using a compact metal-halide PeLED source, we generate random numbers, which are certified to be secure against an eavesdropper, following the quantum measurement-device-independent scenario. The obtained generation rate of more than 10 Mbit s(-1), which is already comparable to commercial devices, shows that PeLEDs can work as high-quality light sources for quantum information tasks, thus opening up future applications in quantum technologies., Funding: CENIIT Linkouml;ping University; Swedish Research Council [2017-04470]; QuantERA grant SECRET [2019-00392]; Knut and Alice Wallenberg Foundation through the Wallenberg Centre for Quantum Technology (WACQT); ERC Starting Grant [717026]; Wallenberg Academy Fellowship; Fondo Nacional de Desarrollo Cientifico y Tecnologico (FONDECYT) [1200859]; ANID-Millennium Science Initiative Program [ICN17_012]; Linkoeping University

Although high-entropy carbides (HECs) have hardness often superior to that of parent compounds, their brittleness-a problem shared with most ceramics-has severely limited their reliability. Refractory HECs in particular are attracting considerable interest due to their unique combination of mechanical and physical properties, tunable over a vast compositional space. Here, combining statistics of crack formation in bulk specimens subject to mild, moderate, and severe nanoindentation loading with ab initio molecular dynamics simulations of alloys under tension, we show that the resistance to fracture of cubic-B1 HECs correlates with their valence electron concentration (VEC). Electronic structure analyses show that VEC greater than or similar to 9.4 electrons per formula unit enhances alloy fracture resistance due to a facile rehybridization of electronic metallic states, which activates transformation plasticity at the yield point. Our work demonstrates a reliable strategy for computationally guided and rule based (i.e., VEC) engineering of deformation mechanisms in high entropy, solid solution, and doped ceramics., Funding Agencies|Swedish Research Council(VR); Competence Center Functional Nanoscale Materials(FunMat-II) [VR-2021-04426]; Olle Engkvist Foundation; Department of Nano Engineerings Materials Research Center (NEMRC); UC San Diego; National Defense Science and Engineering Graduate (NDSEG)Fellowship Program; ARCS Foundation; San Diego Chapter; Oerlikon Group; [2022-03071]

Circularly polarized light (CPL) is widely used for various applications in sensing and imaging(1-3). An ongoing challenge is to realize high-quality CPL detection using chiral organic semiconductors, especially in the near-infrared (NIR) region(4). Chiral molecules tend to rely on twisted stereogenic moieties; however, conventional approaches to reduce the bandgap of organic semiconductors are based on the use of co-planar backbones that commonly lead to molecular symmetries preventing chirality. Here we report a widely applicable strategy to directly induce chiroptical activity in planar non-fullerene acceptors(5-7), which are widely used for high-performance organic photovoltaics and provide a wealth of opportunities to fill the spectral gap of CPL detection in the NIR regime. We demonstrate proof-of-concept circularly polarized organic photodiodes using chiroptically active non-fullerene acceptor blends, which exhibit strong circular dichroism and hence great sensitivity to CPL in the NIR region. Importantly, this strategy is found to be effective in a wide series of state-of-the-art non-fullerene acceptor families including ITIC5, o-IDTBR6 and Y6 analogues(7), which substantially broadens the range of materials applicable to NIR CPL detection., Funding Agencies|Knut and Alice Wallenberg Foundation [KAW 2019.0082]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Stiftelsen for Strategisk Forskning through a Future Research Leader programme [FFL18-0322]; Office of Naval Research [N00014-20-1-2110]; UA College of Science; Linkoping University

X-ray photoelectron spectroscopy (XPS) spectra from solid samples are conventionally referenced to the spectrometer Fermi level (FL). While, in the case of metallic samples, alignment of the sample and the spectrometer FLs can be directly verified from the measured Fermi edge position, thus allowing to assess the surface electrical potential, this is not a workable option for insulators. When applied, it generates a large spread in reported binding energy values that often exceed involved chemical shifts. By depositing insulating amorphous alumina thin films on a variety of conducting substrates with different work functions, we show not only that FL referencing fails but also that the Al2O3 energy levels align instead to the vacuum level, as postulated in the early days of XPS. Based on these model experiments that can be repeated for all sorts of thin-film insulators, a solution to the binding energy reference problem is proposed for reliable assessment of chemical bonding., Funding Agencies|Swedish Research Council VR [2018-03957]; Swedish Energy Agency [51201-1]; Knut and Alice Wallenberg Foundation [KAW2019.0290]; Carl Tryggers Stiftelse [CTS 20:150]; aforsk Foundation [22-4]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University [2009-00971]

Photo-induced dark transient states of fluorophores can pose a problem in fluorescence spectroscopy. However, their typically long lifetimes also make them highly environment sensitive, suggesting fluorophores with prominent dark-state formation yields to be used as microenvironmental sensors in bio-molecular spectroscopy and imaging. In this work, we analyzed the singlet-triplet transitions of fluorescein and three synthesized carboxy-fluorescein derivatives, with one, two or four bromines linked to the anthracence backbone. Using transient state (TRAST) spectroscopy, we found a prominent internal heavy atom (IHA) enhancement of the intersystem crossing (ISC) rates upon bromination, inferred by density functional theory calculations to take place via a higher triplet state, followed by relaxation to the lowest triplet state. A corresponding external heavy atom (EHA) enhancement was found upon adding potassium iodide (KI). Notably, increased KI concentrations still resulted in lowered triplet state buildup in the brominated fluorophores, due to relatively lower enhancements in ISC, than in the triplet decay. Together with an antioxidative effect on the fluorophores, adding KI thus generated a fluorescence enhancement of the brominated fluorophores. By TRAST measurements, analyzing the average fluorescence intensity of fluorescent molecules subject to a systematically varied excitation modulation, dark state transitions within very high triplet yield (>90%) fluorophores can be directly analyzed under biologically relevant conditions. These measurements, not possible by other techniques such as fluorescence correlation spectroscopy, opens for bio-sensing applications based on high triplet yield fluorophores, and for characterization of high triplet yield photodynamic therapy agents, and how they are influenced by IHA and EHA effects., Funding Agencies|Swedish Research Council [VR 2021-04556, VR OQS 2016-06122, CBCS0366]; Swedish Foundation for Strategic Research [VR 2018-05973]; Chemical Biology Consortium Sweden [SSF BENVAC RMX18-0041]

Since the natural narrow bandgaps of free radicals usually lead to emission in the long-wavelength region, it is still of great challenge to design radical luminescent materials with stable and short-wavelength emission in the ambient environment. In this work, a series of dicarbonyl-substituted organic molecules with small conjugated structures were used to form free radicals with short-wavelength radical emission. These low-conjugated mol-ecules with only one benzene ring showed stable photoinduced free radical emission after doping with poly-methyl methacrylate (PMMA) because the rigid polymer environment could help stabilize the free radicals and limit the non-radiative energy transfer. Moreover, PMMA with electron-withdrawing groups could promote the generation of carbonyl radical cations. The theoretical calculation suggests that the free radical with anti-Kasha emission derived from high energy excited state (D4 or D5) would directly relax to the ground state, combining with the small spin delocalization of the low conjugation free radical, leading to short-wavelength emission. More importantly, such free radical emissions could also respond to external stimulation such as light irradiation or heat treatment. These materials show great potential in lithography information recording and information encryption. This design strategy provides new insights into molecular and functional diversity of free radical materials., Funding Agencies|Shanghai Pujiang Program of China [21PJ1400300, 21130750100]; INTERNATIONAL COOPERATION Fund of Science and Technology Commission of Shanghai Municipality [21ZR1402000]; Natural Science Foundation of Shanghai [2232022A-03]; Fundamental Research Funds for the Central Universities [2232022D-06, 202206725]; Swedish Research Council [2120136]; Olle Engkvists Stiftelse (Sweden) [202004600]; [20PJ1400500]; [NAISS 2023/577]

A design concept of phase-separated amorphous nanocomposite thin films is presented that realizes interfacial resistive switching (RS) in hafnium oxide-based devices. The films are formed by incorporating an average of 7% Ba into hafnium oxide during pulsed laser deposition at temperatures <= 400 degrees C. The added Ba prevents the films from crystallizing and leads to similar to 20-nm-thin films consisting of an amorphous HfOx host matrix interspersed with similar to 2-nm-wide, similar to 5-to-10-nm-pitch Ba-rich amorphous nanocolumns penetrating approximately two-thirds through the films. This restricts the RS to an interfacial Schottky-like energy barrier whose magnitude is tuned by ionic migration under an applied electric field. Resulting devices achieve stable cycle-to-cycle, device-to-device, and sample-to-sample reproducibility with a measured switching endurance of >= 10(4) cycles for a memory window >= 10 at switching voltages of +/- 2 V. Each device can be set to multiple intermediate resistance states, which enables synaptic spike-timing-dependent plasticity. The presented concept unlocks additional design variables for RS devices., Funding Agencies|EPSRC; U.S. National Science Foundation [EP/T012218/1-ECCS-EPSRC, ECCS-1902644, ECCS-1902623]; University of Cambridge [EU-H2020-ERC-ADG 882929]; Royal Academy of Engineering [CIET1819_24]; Swedish Research Council [2019-00191, 2021-00357]; Cambridge Herchel Smith postdoctoral fellowship; Royal Academy of Engineering in the form of a Senior Research Fellowship; NNSAs Laboratory Directed Research and Development Program; U.S. Department of Energys NNSA [89233218CNA000001]

The orbital angular momentum (OAM) spatial degree of freedom of light has been widely explored in many applications, including telecommunications, quantum information, and light-based micromanipulation. The ability to separate and distinguish between the different transverse spatial modes is called mode sorting or mode demultiplexing, and it is essential to recover the encoded information in such applications. An ideal d mode sorter should be able to faithfully distinguish between the different d spatial modes, with minimal losses, and have d outputs and fast response times. All previous mode sorters rely on bulk optical elements, such as spatial light modulators, which cannot be quickly tuned and have additional losses if they are to be integrated with optical fiber systems. Here, we propose and experimentally demonstrate, to the best of our knowledge, the first all-in-fiber method for OAM mode sorting with ultrafast dynamic reconfigurability. Our scheme first decomposes the OAM mode in-fiber-optical linearly polarized (LP) modes and then interferometrically recombines them to determine the topological charge, thus correctly sorting the OAM mode. In addition, our setup can also be used to perform ultrafast routing of the OAM modes. These results show a novel and fiber-integrated form of optical spatial mode sorting that can be readily used for many new applications in classical and quantum information processing., Funding Agencies|CENIIT Linkoping University; Swedish Research Council [VR 2017-04470]; Knut and Alice Wallenberg Foundation through the Wallenberg Center for Quantum Technology (WACQT); QuantERA grant SECRET [VR 2019-00392]; Fondo Nacional de Desarrollo Cientifico y Tecnologico (FONDECYT) [3210359, 1230796, 11201348, 1200859]; Millennium Science Initiative Program [ICN17_012]

Non-fullerene acceptors (NFAs) have enabled power conversion efficiencies exceeding 19% in organic solar cells (OSCs). However, the open-circuit voltage of OSCs remains low relative to their optical gap due to excessive non-radiative recombination, and this now limits performance. Here, an important aspect of OSC design is considered, namely management of the triplet exciton population formed after non-geminate charge recombination. By comparing the blends PM6:Y11 and PM6:Y6, it is shown that the greater crystallinity of the NFA domains in PM6:Y11 leads to a higher rate of triplet-triplet annihilation (TTA). This is attributed to the four times larger ground state dipole moment of Y11 versus Y6, which improves the long range NFA out-of-plane ordering. Since TTA converts a fraction of the non-emissive triplet states into bright singlet states, it has the potential to reduce non-radiative voltage losses. Through a kinetic analysis of the recombination processes under 1-Sun illumination, a framework is provided for determining the conditions under which TTA may improve OSC performance. If these could be satisfied, TTA has the potential to reduce non-radiative voltage losses by up to several tens of millivolts., Funding Agencies|Leverhulme Trust [ECF-2022-445]; UK Engineering and Physical Sciences Research Council (EPSRC) Application Targeted and Integrated Photovoltaics (ATIP) project [EP/T028513/1]; UK EPSRC [EP/L016702/1]; EPSRC [EP/W017091/1]; National Natural Science Foundation of China [521253, 22005347]; Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the Research Training School "Molecular biradicals: Structure, properties and reactivity" [GRK2112]; Bavarian Ministry of the Environment and Consumer Protection, the Bavarian Network "Solar Technologies Go Hybrid"; China Scholarship Council (CSC); Research Grant Council of Hong Kong [14303519]

We have found that the polarization dependence of Raman scattering in organic crystals at finite temperatures can only be described by a fourth-rank tensor formalism. This generalization of the second-rank Raman tensor stems from the effect of off diagonal components in the crystal self-energy on the light scattering mechanism. We thus establish a novel manifestation of phonon-phonon interaction in inelastic light scattering, markedly separate from the better-known phonon lifetime., Funding Agencies|European Research Counsel [850041]; Swedish Research Council (VR) [2020-04630]; Belgian National Fund for Scientific Research (FNRS) [T.0072.18, T.0094.22, U.G001.19, O.005018F, O.00322]; French Community of Belgian (ARC) [20061]

Correct binding energy (BE) spectra referencing of insulating samples remains the major challenge in modern XPS analyses. Ar 2p signal of implanted Ar is sometimes used for this purpose. The method relies upon the assumption that chemically inert species such as noble gas atoms would be ideally suited as other factors affecting core level peak positions (such as chemical bonding) can be excluded. Here, we present a systematic study on the Ar 2p referencing method applied to a wide range of thin film sample materials of metals, nitrides, carbides, and borides. All specimens exhibit a well-defined Fermi edge, which serves as an independent internal reference for Ar 2p spectra of in-situ implanted Ar. Ar 2p3/2 binding energy is shown to vary by as much as 5.1 eV between samples. This is more than typical chemical shifts of interest, which obviously disqualifies Ar 2p referencing. The BE of the Ar 2p peaks shows a strong correlation to the number of valence electrons available for screening, implying that the polarization energy has a major role for the observed large spread of Ar 2p3/2 BE values. In several cases of single-phase films, an additional Ar 2p doublet is observed with the Ar 2p3/2 BE referenced to the vacuum level higher than the gas phase value of 248.6 eV, which is tentatively assigned to the formation of Ar-N and Ar-C complexes stabilized by Van der Waals forces. Ar implantation into two-phase samples, exemplified here by phase-segregated NiCrC/a-C:H and nanocomposite c-TiN/SiNx thin films, leads to complex Ar 2p spectra, which further demonstrates unreliability of the referencing method. The firm conclusion of the study is that the Ar 2p3/2 peak from implanted Ar is not a remedy for the charge referencing problem., Funding Agencies|Swedish Research Council VR [2018-03957]; Swedish Energy Agency [51201-1]; Knut and Alice Wallenberg Foundation [KAW2019.0290]; Aforsk Foundation [22-4]; Carl Tryggers Stiftelse [CTS 20:150]; Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

The optical properties of graphene nanodots (GND) and their interaction with phosphate ions have been investigated to explore their potential for optical sensing applications. The absorption spectra of pristine GND and modified GND systems were analyzed using time-dependent density functional theory (TD-DFT) calculation investigations. The results revealed that the size of adsorbed phosphate ions on GND surfaces correlated with the energy gap of the GND systems, leading to significant modifications in their absorption spectra. The introduction of vacancies and metal dopants in GND systems resulted in variations in the absorption bands and shifts in their wavelengths. Moreover, the absorption spectra of GND systems were further altered upon the adsorption of phosphate ions. These findings provide valuable insights into the optical behavior of GND and highlight their potential for the development of sensitive and selective optical sensors for phosphate detection., Funding Agencies|Forsk Foundation [21112]

I ett nyligen avslutat forskningsprojekt har Absolicon Solar Collector tillsammans med RISE Research Institutes of Sweden och Umeå universitet utvecklat en ny toppmodern antireflektiv beläggning som kan göra Absolicons solfångare än mer effektiva. Nu siktar man på ett nytt projekt för att skala upp metoden., Utveckling av Funktionella Ytbeläggningar på Täckglaset för Produktion av Effektivare Solfångare

I ett forskningsprojekt som kommer avslutas vid årsskiftet har framtidens multifunktionella glasytor för solceller utvecklats. Antireflektiva, UV-skyddande, fotokatalytiska och lättrengörliga glasytor är egenskaperna som glasytorna kommer att få. Forskningsidén baseras på tidigare kunskap ifrån forskning vid RISE, Uppsala universitet och KTH och förväntas leda till effektiva solceller med längre livslängd.

Protecting sensitive information is important, especially in defence applications. As cameras become more common, developing countermeasure systems that limit the information gathering capabilities of imaging sensors would be beneficial. Such a countermeasure system can be based on laser dazzling of imaging sensors, which will impair the information gathering capabilities of the sensor if the countermeasur esystem is designed correctly. In order for laser dazzling to be viable as a countermeasure in practical use cases, the dazzling effect needs to be predictable and practically achievable. An existing model predicting the dazzle effect of continuous wave laser irradiance on the front optics of imaging sensors was successfully verified. This was achieved by collecting experimental data using three complementary metal-oxide semiconductor (CMOS) imaging sensors. An amplitude modulated laser was used to dazzle an imaging sensor with the automatic gain control (AGC) and automatic exposure (AE) functions of the sensor enabled. The AGC function dynamically adjusts the image gain and the AE function dynamically adjusts the shutter speed of the sensor to optimise the settings for the given lighting conditions. The impact of the AGC and AE function corrections on the image information content was investigated for a set of lighting conditions, modulation frequencies and modulation duty cycles by collecting data with a CMOS sensor. The dazzling effect was compared to the dazzling effect when using continuous wave lasers. The analysis indicate that the amplitude modulated laser dazzling performance is subpar to the continuous wave laser dazzling performance for the tested configurations. Additionally, the predictability of the modulated laser dazzling effect is complex and depends on more parameters. A model based on this technique would also be sensitive to parameter changes. The weak predictability combined with the subpar performance compared to the continuous wave laser daz

We report on mutual neutralization measurements between 7Li+ and 1H- at effective center-of-mass collision energies in the range of 100 to 350 meV. We find that final states of lithium with principal quantum number n = 3 dominate with 3s separated from the unresolved 3p and 3d states. We measure the 3s branching fraction to be 0.665(12) at 100(16) meV and no significant dependence on collision energy is observed in the studied range. Comparing to previous results on mutual neutralization between 7Li+ and 2H- [G. Eklund et al., Phys. Rev. A 102, 012823 (2020)], we find that 7Li+ collisions with 1H- result in a significantly higher 3s branching fraction than collisions with 2H-. The difference is 0.087(14). The 3s branching fraction of 7Li+ + 1H- and the determined isotope difference are in agreement with results from extended full quantum calculations based on the same input data and numerical method as in Croft et al. [H. Croft, A. S. Dickinson, and F. X. Gadea, J. Phys. B 32, 81 (1999)]. These calculations reveal strong Stueckelberg oscillations of the 3s branching fraction for both isotopes.

The evolution of charge carriers in photoexcited room temperature ZnO nanoparticles in solution is investigated using ultrafast ultraviolet photoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy, and ab initio molecular dynamics (MD) simulations. The photoluminescence is excited at 4.66 eV, well above the band edge, and shows that electron cooling in the conduction band and exciton formation occur in <500 fs, in excellent agreement with theoretical predictions. The x-ray absorption measurements, obtained upon excitation close to the band edge at 3.49 eV, are sensitive to the migration and trapping of holes. They reveal that the 2 ps transient largely reproduces the previously reported transient obtained at 100 ps time delay in synchrotron studies. In addition, the x-ray absorption signal is found to rise in similar to 1.4 ps, which we attribute to the diffusion of holes through the lattice prior to their trapping at singly charged oxygen vacancies. Indeed, the MD simulations show that impulsive trapping of holes induces an ultrafast expansion of the cage of Zn atoms in <200 fs, followed by an oscillatory response at a frequency of similar to 100 cm-1, which corresponds to a phonon mode of the system involving the Zn sub-lattice.

The water oxidation reaction in photosystem II (PS II) produces most of the molecular oxygen in the atmosphere, which sustains life on Earth, and in this process releases four electrons and four protons that drive the downstream process of CO2 fixation in the photosynthetic apparatus. The catalytic center of PS II is an oxygen-bridged Mn4Ca complex (Mn4CaO5) which is progressively oxidized upon the absorption of light by the chloro­phyll of the PS II reaction center, and the accumulation of four oxidative equivalents in the catalytic center results in the oxidation of two waters to di­oxy­gen in the last step. The recent emergence of X-ray free-electron lasers (XFELs) with intense femtosecond X-ray pulses has opened up opportunities to visualize this reaction in PS II as it proceeds through the catalytic cycle. In this review, we summarize our recent studies of the catalytic reaction in PS II by following the structural changes along the reaction pathway via room-temperature X-ray crystallography using XFELs. The evolution of the electron density changes at the Mn complex reveals notable structural changes, including the insertion of OX from a new water molecule, which disappears on completion of the reaction, implicating it in the O—O bond formation reaction. We were also able to follow the structural dynamics of the protein coordinating with the catalytic complex and of channels within the protein that are important for substrate and product transport, revealing well orchestrated conformational changes in response to the electronic changes at the Mn4Ca cluster.

X-ray spectroscopy is a demanded tool across multiple user communities. Here we report on a new station for X-ray emission spectroscopy at the Extreme Light Infrastructure Beamlines Facility. The instrument utilizes the von Hamos geometry and works with a number of different sample types, notably including liquid systems. We demonstrate a simple and reliable method for source position control using two cameras. This approach addresses energy calibration dependence on sample position, which is a characteristic source of measurement uncertainty for wavelength dispersive spectrometers in XES arrangement. We also present a straightforward procedure for energy calibration of liquid and powder samples to a thin film reference. The developed instrumentation enabled us to perform the first experimental determination of the K alpha lines of liquidized K3Fe(CN)6 as well as powdered and liquidized FeNH4(SO4)2. Finally, we report on proof-of-principle use of a colliding jet liquid sample delivery system in an XES experiment.

Free-electron lasers provide bright, ultrashort, and monochromatic x-ray pulses, enabling novel spectroscopic measurements not only with femtosecond temporal resolution: The high fluence of their x-ray pulses can also easily enter the regime of the non-linear x-ray-matter interaction. Entering this regime necessitates a rigorous analysis and reliable prediction of the relevant non-linear processes for future experiment designs. Here, we show non-linear changes in the L-3-edge absorption of metallic nickel thin films, measured with fluences up to 60 J/cm(2). We present a simple but predictive rate model that quantitatively describes spectral changes based on the evolution of electronic populations within the pulse duration. Despite its simplicity, the model reaches good agreement with experimental results over more than three orders of magnitude in fluence, while providing a straightforward understanding of the interplay of physical processes driving the non-linear changes. Our findings provide important insights for the design and evaluation of future high-fluence free-electron laser experiments and contribute to the understanding of non-linear electron dynamics in x-ray absorption processes in solids at the femtosecond timescale.

The Atacama Large Millimeter/submillimeter Array (ALMA) was used in 2021 to image the carbon-rich evolved star R Lep in Bands 8-10 (397-908 GHz) with baselines up to 16 km. The goal was to validate the calibration, using band-to-band (B2B) phase referencing with a close phase calibrator J0504-1512, 1.degrees 2 from R Lep in this case, and the imaging procedures required to obtain the maximum angular resolution achievable with ALMA. Images of the continuum emission and the hydrogen cyanide (HCN) maser line at 890.8 GHz, from the J = 10-9 transition between the (1110) and (0400) vibrationally excited states, achieved angular resolutions of 13, 6, and 5 mas in Bands 8-10, respectively. Self-calibration (self-cal) was used to produce ideal images to compare with the B2B phase referencing technique. The continuum emission was resolved in Bands 9 and 10, leaving too little flux for the self-cal of the longest baselines, so these comparisons are made at coarser resolution. Comparisons showed that B2B phase referencing provided phase corrections sufficient to recover 92%, 83%, and 77% of the ideal image continuum flux densities. The HCN maser was sufficiently compact to obtain self-cal solutions in Band 10 for all baselines (up to 16 km). In Band 10, B2B phase referencing as compared to the ideal images recovered 61% and 70% of the flux density for the HCN maser and continuum, respectively.

Spurred by a need to determine major (C, H, N and O) contents in biological tissue sections, a formalism for quantitative off-axis Scanning Transmission Ion Microscopy (OA-STIM) has been established. This can be used with, or without, simultaneous Elastic Backscattering Spectroscopy (EBS) to provide quantitative major element composition and thickness information. As part of the work, an empirical predictor with one free parameter for the proton-proton differential scattering cross section was implemented. The predictor values were in extremely close agreement with high accuracy literature data. For 2 MeV p(-12)C elastic scattering at forward angles <= 45 degrees an interpolation procedure was used to determine the relative deviations from the Rutherford cross sections were determined to be <= 6.4%. The interpolation was based on a Coulomb field, angular momentum quantum number and nuclear structure dependent nuclear penetration factor. Finally, the quantitative combination of simultaneous OA-STIM and EBS data is discussed.

Synthetic single crystals of bulk molybdenum disulphide cleaved in ultrahigh vacuum are mapped across a large (approximate to 25 mm(2)) area by X-ray photoelectron spectroscopy, both statically and transiently following above-bandgap excitation by an ultrafast laser. This work finds that: I) A cleaved surface typically displays spatially inhomogeneous properties, manifested by large (approximate to 1 eV) variations in binding energy and band bending and variable degrees of stability of those over time as a result of variable gas uptakes from the residual atmosphere. II) Moderate (350 degrees C) annealing and exposure to molecular hydrogen can be cycled to switch between smaller and larger surface band bending, the switch being reversible but strongly sample-position dependent. III) Upon exposure to atomic hydrogen, the binding energy of the entire surface levels out to a common (within <0.05 eV) value corresponding to a Fermi level pinned close to mid-bandgap. Such remarkable effect is attributed to the ability of hydrogen atoms to serve as donors and acceptors alike, thus neutralizing local charge imbalances inevitably present at the surface in consequence of intrinsic and/or cleavage-induced defects. With subsequent moderate annealing, the hydrogenated surface preserves a fairly homogenous electronic state which is however characterized by a lower binding energy and little to no band bending.

Optical upconversion via a multiphoton absorption processconvertsincoherent low-energy photons to shorter wavelengths. In this contribution,we report a solid-state thin film for infrared-to-visible upconversioncomposed of plasmonic/TiO2 interfaces. When excited at & lambda; = 800 nm, three photons are absorbed, leading to the excitationof TiO2 trap states into an emissive state in the visibledomain. The plasmonic nanoparticle enhances the light absorption capabilitiesof the semiconductor, increasing emission efficiency by 20 times.We demonstrate that the plasmonic nanoparticle only changes the opticalabsorption of the semiconductor; i.e., the process is purely photonic.The process occurs in the ultrafast domain (<10 ps), contrastingwith molecular triplet-triplet exciton annihilation, the commonlyused method in photon upconversion, in the nano- to microsecond timescales. The process utilizes pre-existing trap states within the semiconductorbandgap and involves three-photon absorption.

In organic solar cells with very small energetic-offset (& UDelta;ELE - CT), the charge-transfer (CT) and local-exciton (LE) states strongly interact via electronic hybridization and thermal population effects, suppressing the non-radiative recombination. Here, we investigated the impact of these effects on charge generation and recombination. In the blends of PTO2:C8IC and PTO2:Y6 with very small, ultra-fast CT state formation was observed, and assigned to direct photoexcitation resulting from strong hybridization of the LE and CT states (i.e., LE-CT intermixed states). These states in turn accelerate the recombination of both CT and charge separated (CS) states. Moreover, they can be significantly weakened by an external-electric field, which enhanced the yield of CT and CS states but attenuated the emission of the device. This study highlights that excessive LE-CT hybridization due to very low , whilst enabling direct and ultrafast charge transfer and increasing the proportion of radiative versus non-radiative recombination rates, comes at the expense of accelerating recombination losses competing with exciton-to-charge conversion process, resulting in a loss of photocurrent generation., Funding Agencies|Swedish Research Council VR [2019-00677]; National Natural Science Foundation of China (NSFC) [51973146]; Shandong Provincial Natural Science Foundation [ZR2022JQ09]; Collaborative Innovation Center of Suzhou Nano Science amp; Technology; EPSRC project ATIP [EP/TO28513/1]; Office of Naval Research [N00014-20-1-2110]