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Long-range interparticle interactions are revealed in extremely dilute thermal atomic ensembles using highly sensitive nonlinear femtosecond spectroscopy. Delocalized excitons are detected in the atomic systems at particle densities where the mean interatomic distance (>10 μm) is much greater than the laser wavelength and multi-particle coherences should destructively interfere over the ensemble average. With a combined experimental and theoretical analysis, we identify an effective interaction mechanism, presumably of dipolar nature, as the origin of the excitonic signals. Our study implies that even in highly-dilute thermal atom ensembles, significant transition dipole-dipole interaction networks may form that require advanced modeling beyond the nearest neighbor approximation to quantitatively capture the details of their many-body properties.
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http://dx.doi.org/10.1039/c8cp05851b | DOI Listing |
J Chem Theory Comput
September 2025
International Center for Quantum and Molecular Structures, Faculty of Physics, Shanghai University, Shanghai 200444, China.
The representation of the electronic structure of benzene is important for understanding the properties of planar and monocyclic organic carbon compounds. Resonant Kekulé and conjugated structures based on localized and delocalized electronic theories, respectively, can be used to depict the ground state of benzene; however, depictions of its electrons vibrating in the excited states remain to be clarified. This paper presents a novel algorithm for exploring the three lowest lying vertically singlet excited states of benzene, focusing on the electronic excitations between occupied π and unoccupied π* orbitals.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
August 2025
Key Laboratory of Materials Physics of Ministry of Education, School of Physics, Zhengzhou University, Daxue Road 75, Zhengzhou, 450052, China.
Organic-inorganic antimony (Sb) halides are garnering increasing interest for lead-free perovskite light-emitting diodes (LEDs), but the non-radiative recombination and poor charge transport are hard-treat case to restrict their electroluminescent performance. Here we developed efficient Sb halide LEDs based on the tailor-made host-guest (PhP)SbCl (PhP = tetraphenylphosphonium) emitters that enable good luminescence and charge transport properties simultaneously. Experimental and theoretical studies reveal that the self-trapped excitons triggered by excited-state structural deformation were localized in spatial-confined [SbCl] polyhedrons, generating a high photoluminescence quantum yield (96.
View Article and Find Full Text PDFJ Chem Phys
August 2025
Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via Marzolo 1, Padua 35131, Italy.
We investigate the spectral features of Action-2D Electronic Spectroscopy (A-2DES) using a molecular dimer model across different regimes of excitonic coupling. By explicitly including a second-excited state for each chromophore, we simulate A-2DES spectra ranging from the non-interacting limit to the strong-coupling case, focusing on the significance of cross peaks. While for weak excitonic coupling, cross peaks can be understood as the incoherent mixing of linear signals of the two chromophores, these features reflect excitonic delocalization as the coupling increases.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K.
In recent years, significant progress has been made in improving the stability, photocurrent efficiency and charge transport properties of 2D hybrid perovskites, making them increasingly relevant for optoelectronic devices. Although these layered systems are typically considered quantum wells due to carrier confinement, an emerging strategy is to generate new perovskite functionalities with π-conjugated electroactive cores as spacer molecules, which introduce electronic coupling between the inorganic metal-halide and organic sublattices. Realizing these functionalities requires an understanding of how this coupling is achieved and how it affects exciton behavior.
View Article and Find Full Text PDFJ Phys Chem Lett
September 2025
School of Chemistry and Chemical Engineering, Ministry of Education Key Laboratory of Special Functional Aggregated Materials, Shandong Key Laboratory of Advanced Organosilicon Materials and Technologies, Shandong University, Jinan 250100, China.
Ruddlesden-Popper phases CsCdCl and CsCdCl are widely used in experimental research of optoelectronics due to their excellent doping matrix properties, but their optoelectronic mechanisms have not been fully explored. This study uses first-principles calculations and experiments to analyze the differences in point defect crystal growth and optoelectronic properties caused by Sb doping of these two materials. Sb tends to replace the position of Cd in both structures.
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