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We revisit the resonant break-up of 19 C on protons at intermediate energies. In this reaction, it was found, for the first time in a halo nucleus to our knowledge, that the cross section was largely dominated by the excitation of the core. In this contribution, we study the robustness of this conclusion against the choice of different optical potentials for the core.

A photon avalanche (PA) effect that occurs in lanthanide-doped solids gives rise to a giant nonlinear response in the luminescence intensity to the excitation light intensity. As a result, much weaker lasers are needed to evoke such PAs than for other nonlinear optical processes. Photon avalanches are mostly restricted to bulk materials and conventionally rely on sophisticated excitation schemes, specific for each individual system. Here we show a universal strategy, based on a migrating photon avalanche (MPA) mechanism, to generate huge optical nonlinearities from various lanthanide emitters located in multilayer core/shell nanostructrues. The core of the MPA nanoparticle, composed of Yb 3+ and Pr 3+ ions, activates avalanche looping cycles, where PAs are synchronously achieved for both Yb 3+ and Pr 3+ ions under 852 nm laser excitation. These nanocrystals exhibit a 26th-order nonlinearity and a clear pumping threshold of 60 kW cm −2 . In addition, we demonstrate that the avalanching Yb 3+ ions can migrate their optical nonlinear response to other emitters (for example, Ho 3+ and Tm 3+ ) located in the outer shell layer, resulting in an even higher-order nonlinearity (up to the 46th for Tm 3+ ) due to further cascading multiplicative effects. Our strategy therefore provides a facile route to achieve giant optical nonlinearity in different emitters. Finally, we also demonstrate applicability of MPA emitters to bioimaging, achieving a lateral resolution of ~62 nm using one low-power 852 nm continuous-wave laser beam. A general mechanism, migrating photon avalanche, can generate large optical nonlinearity from various lanthanides emitters at the nanoscale.

Exciton polaron is a hypothetical many-body quasiparticle that involves an exciton dressed with a polarized electron-hole cloud in the Fermi sea. It has been evoked to explain the excitonic spectra of charged monolayer transition metal dichalcogenides, but the studies were limited to the ground state. Here we measure the reflection and photoluminescence of monolayer MoSe 2 and WSe 2 gating devices encapsulated by boron nitride. We observe gate-tunable exciton polarons associated with the 1 s–3 s exciton Rydberg states. The ground and excited exciton polarons exhibit comparable energy redshift (15~30 meV) from their respective bare excitons. The robust excited states contradict the trion picture because the trions are expected to dissociate in the excited states. When the Fermi sea expands, we observe increasingly severe suppression and steep energy shift from low to high exciton-polaron Rydberg states. Their gate-dependent energy shifts go beyond the trion description but match our exciton-polaron theory. Our experiment and theory demonstrate the exciton-polaron nature of both the ground and excited excitonic states in charged monolayer MoSe 2 and WSe 2 . An exciton polaron is a quasiparticle composed of an exciton dressed with an electron-hole cloud, and this concept has been used to explain the ground excitonic states in charged monolayer transition metal dichalcogenides. Here the authors present experimental and theoretical evidence of exciton-polaron Rydberg states in monolayer MoSe 2 and WSe 2 .

In van der Waals (vdW) materials, strong coupling between different degrees of freedom can hybridize elementary excitations into bound states with mixed character 1 – 3 . Correctly identifying the nature and composition of these bound states is key to understanding their ground state properties and excitation spectra 4 , 5 . Here, we use ultrafast spectroscopy to reveal bound states of d -orbitals and phonons in 2D vdW antiferromagnet NiPS 3 . These bound states manifest themselves through equally spaced phonon replicas in frequency domain. These states are optically dark above the Néel temperature and become accessible with magnetic order. By launching this phonon and spectrally tracking its amplitude, we establish the electronic origin of bound states as localized d – d excitations. Our data directly yield electron-phonon coupling strength which exceeds the highest known value in 2D systems 6 . These results demonstrate NiPS 3 as a platform to study strong interactions between spins, orbitals and lattice, and open pathways to coherent control of 2D magnets. Van der Waals materials can exhibit strong coupling between the lattice and other degrees of freedom. Here, Ergeçen et al reveal the presence of bound states emerging from the strong interaction between the lattice vibrations and d -orbitals in the van der Waals antiferromagnet NiPS 3 .

Quantum states depend on the coordinates of all their constituent particles, with essential multi-particle correlations. Time-resolved laser spectroscopy 1 is widely used to probe the energies and dynamics of excited particles and quasiparticles such as electrons and holes 2 , 3 , excitons 4 – 6 , plasmons 7 , polaritons 8 or phonons 9 . However, nonlinear signals from single- and multiple-particle excitations are all present simultaneously and cannot be disentangled without a priori knowledge of the system 4 , 10 . Here, we show that transient absorption—the most commonly used nonlinear spectroscopy—with N prescribed excitation intensities allows separation of the dynamics into N increasingly nonlinear contributions; in systems well-described by discrete excitations, these N contributions systematically report on zero to N excitations. We obtain clean single-particle dynamics even at high excitation intensities and can systematically increase the number of interacting particles, infer their interaction energies and reconstruct their dynamics, which are not measurable via conventional means. We extract single- and multiple-exciton dynamics in squaraine polymers 11 , 12 and, contrary to common assumption 6 , 13 , we find that the excitons, on average, meet several times before annihilating. This surprising ability of excitons to survive encounters is important for efficient organic photovoltaics 14 , 15 . As we demonstrate on five diverse systems, our procedure is general, independent of the measured system or type of observed (quasi)particle and straightforward to implement. We envision future applicability in the probing of (quasi)particle interactions in such diverse areas as plasmonics 7 , Auger recombination 2 and exciton correlations in quantum dots 5 , 16 , 17 , singlet fission 18 , exciton interactions in two-dimensional materials 19 and in molecules 20 , 21 , carrier multiplication 22 , multiphonon scattering 9 or polariton–polariton interaction 8 . Transient absorption with N prescribed excitation intensities allows isolation of N increasingly nonlinear responses, enabling separation of single- and multiple-exciton dynamics.

The Excitation functions of ^sup 40^Ar(p,p'[gamma])^sup 40^Ar and ^sup 40^Ar(p,[gamma])^sup 41^K reactions are measured in the E p = 1.0-3.0 eV range of accelerated protons. The excitation function in the E p > 2.6 MeV range of accelerated protons is measured for the first time. The strengths of all (more than 200) measured resonance states are calculated.

Acute occlusive myocardial infarction (OMI) complicated by ventricular pre‐excitation can present diagnostic challenges. This case describes a 78‐year‐old male with an 11‐h history of chest tightness. A reduction was observed in the extent of localized ventricular pre‐excitation, accompanied by secondary ST–T segment abnormalities in leads V1–V3. Emergency coronary angiography revealed occlusion of the left anterior descending artery. This case highlights that a decrease in the extent of local ventricular pre‐excitation in R–wave–dominant leads, combined with inference of the accessory pathway location and its potential correlation with the occluded vessel, may facilitate early identification of OMI. This case report describes a potential electrocardiographic manifestation of ventricular pre‐excitation concealing a typical ST‐segment elevation myocardial infarction and provides a systematic analysis of the underlying pathophysiological mechanisms.

In order to study the thermal safety of high passivation semiconductor bridges, a NTC (negative temperature coefficient) thermistor is integrated into the SCB (Semiconductor Bridge), and the SCB-NTC shunt and the temperature change in the bridge area and the temperature change in the bridge area of the SCB are investigated based on the COMSOL under the excitation of different constant current sources. The results show that NTC has an obvious inhibiting effect on the temperature increase of SCB bridge area. The thermal equilibrium temperature of the bridge area is about 172 °C under 1.5 A excitation condition; under 2 A excitation condition, the thermal equilibrium temperature of the bridge area is about 206 °C. The current flowing through the NTC under 1.5 A excitation condition rises from 0.45 A to 0.78 A and stays unchanged; under 2 A excitation condition, the current flowing through the NTC rises from 0.6 A to 1.35 A and stays unchanged. By integrating the NTC on the SCB, the NTC thermistor shunt can reach 52%∼67.5%, which can reduce the temperature of the bridge area by 55%∼70%. The above simulation results are compared with the experimental results, and the simulation results are in high agreement with the experimental results.

This article briefly described the mechanism of transformer magnetizing inrush current, and introduced the principle of differential protection magnetizing inrush current suppression of Siemens 7UT682 protection device. Through the analysis and research of a differential protection malfunction trip event when a no-load closing power of a overhauled transformer, the method of optimizing the relevant parameter configuration of the protection device to avoid the excitation inrush current was proposed and achieved good application results.

Generally, the hydraulic pipe of a warplane experiences the pulsating flow generated by the plunger pump and the strong excitation generated by the jet engine. Furthermore, the pipe is situated in a high-temperature environment due to its proximity to the jet engine. Considering the combined influence of the thermal environment and excitation, this study presents a unique nonlinear resonance phenomenon in the hydraulic pipe for the first time. The governing equation is derived based on the Euler–Bernoulli beam theory and the generalized Hamilton’s principle. The steady-state response is analyzed using the direct multi-scale method, and the stability of the response curve is examined using the Routh–Hurwitz criterion. Runge–Kutta method verifies the approximate analytical results. Using the direct multi-scale method, the effects of temperature, pulsating velocity and external excitation amplitude on the pipe’s dynamics are investigated in detail. By comparing the stable boundary of the hydraulic pipe before and after buckling under the combined excitation, it is observed that the stability of the combined excitation is unaffected by the external excitation amplitude. The study also reveals that pulsating velocity and external excitation amplitude enhance the response, while an increase in temperature reduces the subcritical response and enhances the supercritical response. Additionally, temperature increments alter the range of excitation where the jumping phenomenon occurs. This research provides valuable theoretical guidance for the design of warplane jet engines.