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Current X-ray imaging technologies involving flat-panel detectors have difficulty in imaging three-dimensional objects because fabrication of large-area, flexible, silicon-based photodetectors on highly curved surfaces remains a challenge 1 – 3 . Here we demonstrate ultralong-lived X-ray trapping for flat-panel-free, high-resolution, three-dimensional imaging using a series of solution-processable, lanthanide-doped nanoscintillators. Corroborated by quantum mechanical simulations of defect formation and electronic structures, our experimental characterizations reveal that slow hopping of trapped electrons due to radiation-triggered anionic migration in host lattices can induce more than 30 days of persistent radioluminescence. We further demonstrate X-ray luminescence extension imaging with resolution greater than 20 line pairs per millimetre and optical memory longer than 15 days. These findings provide insight into mechanisms underlying X-ray energy conversion through enduring electron trapping and offer a paradigm to motivate future research in wearable X-ray detectors for patient-centred radiography and mammography, imaging-guided therapeutics, high-energy physics and deep learning in radiology. Using lanthanide-doped nanomaterials and flexible substrates, an approach that enables flat-panel-free, high-resolution, three-dimensional imaging is demonstrated and termed X-ray luminescence extension imaging.

This study presents evidence of stably trapped electrons at Jupiter's moon Ganymede. We model energetic electron pitch angle distributions and compare them to observations from the Galileo Energetic Particle Detector to identify signatures of trapped particles during the G28 encounter. We trace electron trajectories to show that they enter Ganymede's mini‐magnetospheric environment, become trapped, and drift around the moon for up to 30 min, in some cases stably orbiting the moon multiple times. Conservation of the first adiabatic invariant partially contributes to energy changes throughout the electrons' orbits, with additional acceleration driven by local electric fields, before they return to Jupiter's magnetosphere or impact the surface. These trapped particles manifest as an electron population with an enhanced flux compared to elsewhere within the mini‐magnetosphere that are detectable by future spacecraft. Plain Language Summary The magnetized planets of the solar system are known to possess a population of high‐energy, orbiting electrons that are sustained for extended timescales. By comparison, Ganymede, the only moon in the solar system confirmed to have its own permanent magnetic field, should also retain a similar population of trapped particles. Observations from the Galileo mission hint at the existence of electrons that may be locally trapped at the moon, but information regarding their origin and the mechanism behind trapping these electrons is unknown. Furthermore, there are no constraints on the processes that help sustain such a trapped population, and the timescales over which they are maintained at Ganymede remain unknown. In this study, we provide evidence that trapped electrons exist at Ganymede, identify the mechanisms driving their dynamics, and answer open questions about the moon's local energetic particle environment. Key Points We compare Galileo G28 energetic electron data with test particle tracing to identify a population of trapped electrons at Ganymede We achieve a robust match between the energetic electron pitch angle distributions from our model compared to those observed by Galileo Electrons follow stable orbits that can encircle the moon multiple times before being lost to the surface or to Jupiter's magnetosphere

We analyzed the contribution of electromagnetic ion cyclotron (EMIC) wave driven electron loss to a flux dropout event in September 2017. The evolution of electron phase space density (PSD) through the dropout showed the formation of a radially peaked PSD profile as electrons were lost at high L*, resembling distributions created by magnetopause shadowing. By comparing 2D Fokker Planck simulations of pitch angle diffusion to the observed change in PSD, we found that the μ and K of electron loss aligned with maximum scattering rates at dropout onset. We conclude that, during this dropout event, EMIC waves produced substantial electron loss. Because pitch angle diffusion occurred on closed drift paths near the last closed drift shell, no radial PSD minimum was observed. Therefore, the radial PSD gradients resembled solely magnetopause shadowing loss, even though the local pitch angle scattering produced electron losses of several orders of magnitude of the PSD. Plain Language Summary Extremely energetic charged particles become trapped by Earth's geomagnetic field, forming the Van Allen radiation belts. The total amount of radiation trapped within these belts varies depending on the solar wind conditions, which can disturb the geomagnetic field to produce geomagnetic storms. At the beginning of a geomagnetic storm, there is a relative calm in the radiation belt, produced by the rapid drainage of electrons from the geomagnetic field. It is not fully understood if these electrons are primarily lost into the solar wind, or if they are lost into Earth's atmosphere. In this study, we analyze the remaining trapped electrons to reconstruct the mechanisms of electron escape at the beginning of a geomagnetic storm in September 2017. While previous work found that electrons were primarily lost into the solar wind, we found that loss into the atmosphere also played an important role. Furthermore, we showed that drainage of electrons into the atmosphere can be mistaken for loss into the solar wind if the energy and trajectory of lost electrons are not carefully considered. Key Points Characterizing electron loss through peaks and minima in radial phase space density can misrepresent simultaneous loss mechanisms Analysis of electron loss across all adiabatic invariants μ, K, and L*, is necessary to correctly identify loss mechanisms Observational analysis of phase space density data alone cannot be used to quantify individual contributions of simultaneous loss processes

Energetic electron spectra in Earth's inner radiation belt often exhibit regular stripe‐like features, known as “zebra stripes,” which are typically attributed to the drift motion of stably‐trapped electrons disturbed by electric field perturbations. Using high‐quality electron measurements from the Macao Science Satellite‐1, we report the first observation of zebra stripe structures in quasi‐trapped electrons within the inner radiation belt. Through a combination of data analysis and test particle simulations, we show that the formation of quasi‐trapped stripes follows a two‐step radial transport driven by dual‐pulse electric fields. The first electric field generates zebra stripes in the stably‐trapped region, while the second moves them further inward into the quasi‐trapped zone, where they are identified as quasi‐trapped zebra stripes. These findings offer new insights into utilizing electron observations to diagnose the morphology and temporal profile of large‐scale electric fields within the inner radiation belt.

The outward transport of plasma and magnetic fluxes in the gas giant magnetospheres is balanced with a return flow of flux tubes emptied through magnetic reconnection. Evidence of interchange motions between inward and outward moving flux tubes have long been reported around Jupiter and Saturn. Although amply documented at Saturn, the lack of useable low energy plasma data has prevented the analysis of their plasma properties at Jupiter. The Juno data sets allow us to characterize the plasma populations inside nine interchange events at Jupiter between M‐shells 5 and 10. We confirm that they are strongly depleted in heavy ions and low energy protons and electrons, but filled with higher energy protons and electrons. We model the pitch‐angle distribution of trapped electrons through adiabatic transport and estimate that the reported flux tubes were likely isotropic between M‐shells 11 and 35. The observed features bear strong similarities with their Kronian counterparts.

Field Line Resonances (FLRs) are a critical component in Earth's magnetospheric dynamics, associated with the transfer of energy between Ultra Low Frequency waves and local plasma populations. In this study we investigate how the polarisation of FLRs are impacted by cold plasma density distributions during geomagnetic storms. We present an analysis of Van Allen Probe A observations, where the spacecraft traversed a storm time plasmaspheric plume. We show that the polarisation of the FLR is significantly altered at the sharp azimuthal density gradient of the plume boundary, where the polarisation is intermediate with significant poloidal and toroidal components. These signatures are consistent with magnetohydrodynamic modeling results, providing the first observational evidence of a 3D FLR associated with a plume in Earth's magnetosphere. These results demonstrate the importance of cold plasma in controlling wave dynamics in the magnetosphere, and have important implications for wave‐particle interactions at a range of energies. Plain Language Summary Earth's space environment is home to electrons and ions across a wide range of energies, trapped in the region by our global geomagnetic field. Energy can be transferred to and from the trapped particles through oscillations in the magnetic field, and these processes are responsible for the extreme energization of trapped electrons to hazardous levels for local spacecraft. In this paper we explore a type of magnetic field oscillation termed Field Line Resonances (FLRs): standing waves on a field line analogous to the oscillatory motion of guitar strings. We use spacecraft observations to show that the direction of the field line oscillations changes significantly depending on the density of the background plasma. The results confirm previous modeling work, and are the first observational evidence of 3D FLRs at a plume. The findings have important consequences for how FLRs transfer energy between the electrons and ions. Key Points We present the first observational evidence of a 3D Field Line Resonance at the sharp density gradient of a plume edge The observed polarisation change confirms magnetohydrodynamic modeling results and predictions made by Elsden and Wright (2022) The presence of 3D Field Line Resonances during storm times has impacts for how Ultra Low Frequency waves couple and interact with local plasma

Mercury has a large loss cone difference in its two hemispheres due to the northward shifted magnetic dipole. The precipitation difference of energetic electrons in both hemispheres is poorly understood. We show that the northern precipitation is 2.5‐times higher than for a symmetric loss cone due to the effects of the enhanced whistler instability at the southern hemisphere with the larger loss cone. Simulations including nonlinear pitch angle scattering by the whistler‐mode waves show rapid (tens of milliseconds) electron flux modulation related to the wave subpacket structures by repeated interactions within a discrete wave element. The difference in the nonlinear whistler instability in the two hemispheres should enhance the electron precipitation, which, along with the direct impact effects of solar wind, contributes to Mercury's surface–magnetosphere coupling. Electrons hitting the planet's surface may be a possible factor in the formation of water through the formation of hydroxyl groups. Plain Language Summary Mercury, the first planet from the Sun, has north–south asymmetric magnetic fields due to the northward shifted magnetic dipole from the planet's center. Computer simulations of plasma waves and electrons, taking into account Mercury's magnetic dipole offset, show that the northward precipitation of electrons is 2.5‐times higher than in the case of no magnetic dipole offset, which is the case like the Earth. This difference in electron precipitation fraction arises from a difference in the characteristics of wave growth due to the spatial characteristics of the planet's magnetic field, because plasma waves can efficiently push trapped electrons in Mercury's magnetosphere toward the planet's surface. This study contributes to the understanding of the electron precipitation fraction on Mercury and may help to estimate the production of water ice through the formation of hydroxyl groups not only by the direct impact of solar wind but also by the electron precipitation caused by plasma waves. Key Points Whistler‐driven electrons at Mercury are simulated, as the electron precipitation on the planet surface may contribute to water production For an asymmetric (southward wider) loss cone, the northward precipitation fraction is 2.5‐times higher than for a symmetric loss cone Rapid (tens of milliseconds) electron flux modulations can be observed as a signature of repeated interactions with wave subpackets

The relaxation dynamics of the photoexcited hydrated electron have been subject to conflicting interpretations. Here, we report time-resolved photoelectron spectra of hydrated electrons in a liquid microjet with the aim of clarifying ambiguities from previous experiments. A sequence of three ultrashort laser pulses (~100 femtosecond duration) successively created hydrated electrons by charge-transfer-to-solvent excitation of dissolved anions, electronically excited these electrons via the s→p transition, and then ejected them into vacuum. Two distinct transient signals were observed. One was assigned to the initially excited p-state with a lifetime of ~75 femtoseconds, and the other, with a lifetime of ~400 femtoseconds, was attributed to s-state electrons just after internal conversion in a nonequilibrated solvent environment. These assignments support the nonadiabatic relaxation model.

Electrons, photogenerated in conduction bands (CB) and trapped in electron trap defects (Tids) in titanium dioxide (TiO2), play crucial roles in characteristic reductive reactions. This review summarizes the recent progress in the research on electron transfer in photo-excited TiO2. Particularly, the reactivity of electrons accumulated in CB and trapped at Tids on TiO2 is highlighted in the reduction of molecular oxygen and molecular nitrogen, and the hydrogenation and dehalogenation of organic substrates. Finally, the prospects for developing highly active TiO2 photocatalysts are discussed.

Since the discovery of the hydrated electron more than 40 years ago, a general consensus has emerged that the hydrated electron occupies a quasispherical cavity in liquid water. We simulated the electronic structure and dynamics of the hydrated electron using a rigorously derived pseudopotential to treat the electron-water interaction, which incorporates attractive oxygen and repulsive hydrogen features that have not been included in previous pseudopotentials. What emerged was a hydrated electron that did not reside in a cavity but instead occupied a approximately 1-nanometer-diameter region of enhanced water density. Both the calculated ground-state absorption spectrum and the excited-state spectral dynamics after simulated photoexcitation of this noncavity hydrated electron showed excellent agreement with experiment. The relaxation pathway involves a rapid internal conversion followed by slow ground-state cooling, the opposite of the mechanism implicated by simulations in which the hydrated electron occupies a cavity.