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Conformational change due to intramolecular hydrophobic interaction leads to large blue-shifted emission from single molecular cage solutions
摘要： We demonstrate a unique negative solvatochromic emission (NSE) process from a conformational change of a coordination cage in response to solvent composition. The cationic cage contains two tetra-(4-pyridylphenyl)ethylene (TPPE) luminogens on two opposite faces, linked by Pt(PEt3)2 and isophthalate. When the solvent changes from acetone/acetonitrile/methanol to water, the emission of single cages gradually shifts to short wavelength (NSE) with a drastic value of B60 nm. Small angle X-ray scattering (SAXS) measurements indicate a molecular conformational change during the process and intramolecular p–p stacking and hydrophobic interaction between the TPPE planes could be the driving forces. As a comparison, a cage with a longer inter-fluorophore distance does not have such strong intramolecular interactions and only shows regular positive solvatochromic emission (PSE) under the same conditions.
关键词： coordination cage,intramolecular hydrophobic interaction,small angle X-ray scattering,TPPE luminogens,negative solvatochromic emission
更新于2025-09-04 15:30:14
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Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy
摘要： A hallmark in the cuprate family of high-temperature superconductors is the nodal-antinodal dichotomy. In this regard, angle-resolved photoemission spectroscopy (ARPES) has proven especially powerful, providing band structure information directly in energy-momentum space. Time-resolved ARPES (trARPES) holds great promise of adding ultrafast temporal information, in an attempt to identify different interaction channels in the time domain. Previous studies of the cuprates using trARPES were handicapped by the low probing energy, which significantly limits the accessible momentum space. Using 20.15 eV, 12 fs pulses, we show for the first time the evolution of quasiparticles in the antinodal region of Bi2Sr2CaCu2O8+d and demonstrate that non-monotonic relaxation dynamics dominates above a certain fluence threshold. The dynamics is heavily influenced by transient modification of the electron-phonon interaction and phase space restrictions, in stark contrast to the monotonic relaxation in the nodal and off-nodal regions.
关键词： electron-phonon interaction,high-temperature superconductors,cuprate,time-resolved ARPES,nodal-antinodal dichotomy,angle-resolved photoemission spectroscopy,quasiparticles
更新于2025-09-04 15:30:14
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Blocked populations in ring-shaped optical lattices
摘要： We study a special dynamical regime of a Bose-Einstein condensate in a ring-shaped lattice where the populations in each site remain constant during the time evolution. The states in this regime are characterized by equal occupation numbers in alternate wells and nontrivial phases, while the phase differences between neighboring sites evolve in time yielding persistent currents that oscillate around the lattice. We show that the velocity circulation around the ring lattice alternates between two values determined by the number of wells and with a specific time period that is only driven by the on-site interaction energy parameter. In contrast to the self-trapping regime present in optical lattices, the occupation number at each site does not show any oscillation and the particle imbalance does not possess a lower bound for the phenomenon to occur. These findings are predicted with a multimode model and confirmed by full three-dimensional Gross-Pitaevskii simulations using an effective on-site interaction energy parameter.
关键词： on-site interaction energy,Bose-Einstein condensate,persistent currents,Gross-Pitaevskii simulations,multimode model,ring-shaped lattice
更新于2025-09-04 15:30:14
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Impact of Low‐Frequency Vibrations on Charge Transport in High‐Mobility Organic Semiconductors
摘要： Despite decades of intensive studies of charge transport in organic semiconductors (OSs), understanding of mechanisms underpinning efficient charge transport in them remains elusive. Recently, it has been suggested that low-frequency (LF) vibrations are a limiting factor of charge transport in high-mobility OSs. Nevertheless, the relationship between the molecular structure, crystal packing, LF vibrations, and charge transport is still obscured. This hinders the focused search of high-mobility OSs so that researchers rely mainly on trial-and-error method. This review presents theoretical and experimental approaches to studying the LF vibrations and their role in charge transport with a focus on recent results. It is anticipated that tight cooperation between experimentalists and theorists will yield an advanced understanding of LF vibrations in OSs and their impact on charge transport. This will guide the design of novel high-mobility organic semiconductors for organic electronics.
关键词： structure–property relationship,organic electronics,Raman spectroscopy,electron–phonon interaction,charge mobility
更新于2025-09-04 15:30:14
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Photodetection probability in quantum systems with arbitrarily strong light-matter interaction
摘要： Cavity-QED systems have recently reached a regime where the light-matter interaction strength amounts to a non-negligible fraction of the resonance frequencies of the bare subsystems. In this regime, it is known that the usual normal-order correlation functions for the cavity-photon operators fail to describe both the rate and the statistics of emitted photons. Following Glauber’s original approach, we derive a simple and general quantum theory of photodetection, valid for arbitrary light-matter interaction strengths. Our derivation uses Fermi’s golden rule, together with an expansion of system operators in the eigenbasis of the interacting light-matter system, to arrive at the correct photodetection probabilities. We consider both narrow- and wide-band photodetectors. Our description is also valid for point-like detectors placed inside the optical cavity. As an application, we propose a gedanken experiment confirming the virtual nature of the bare excitations that enrich the ground state of the quantum Rabi model.
关键词： Cavity-QED,light-matter interaction,ultrastrong coupling,quantum Rabi model,photodetection
更新于2025-09-04 15:30:14