Singlet-triplet energy gaps modulation of Diindeno [1,2-b: 1’2’-g] anthracene molecular family

Nowadays there is a large interest in organic materials based on diradical polycyclic aromatic hydrocarbons (PAHs) due to their unique properties, such as narrow frontier-orbital energy gaps, strong absorption in the visible spectrum, etc. However, the inherent diradical nature make these compounds with limited chemical stability giving rise to rapid decomposition under ambient conditions thus reducing their practical use. In recent years PAH diradicals that exhibit remarkable stability have been prepared thanks to the description of efficient synthetic routes to access them. One of these remarkable cases is the diindeno [1,2-b: 1’2’-g] anthracene, named as DIAn. DIAn is constituted by antiaromatic segments together with a central pro-aromatic structure. One of the important observable properties of diradicals is the singlet-triplet energy gap, ∆EST, which is intimately connected with the diradical character. The possibility of access to the molecular structure of diradicals is very valuable since properties such as the bond-order or the bond-length alternation of the mentioned moieties reveal the diradical content. Electronic and vibrational spectroscopies are alternative sources of structural information that often compensate the absence of solid-state structures. In this communication, we expand the studies of DIAn by introducing another aspect of the modulation of the ∆EST which concerns with: i) the extension of the terminal benzenes with another fused benzene (i.e., forming terminal napthalenes) and ii) with the isomerization resulting from the fusion topology of these terminal benzenes. We will present a UV-Vis-NIR and Raman spectroscopic study of the new compounds. The variation of the spectra within molecular family will be discussed in connection with the variation of ∆EST and with the diradical character of the new molecules.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Orbital Nature of Carboionic Monoradicals Made from Diradicals

The electronic, optical, and solid state properties of a series of monoradicals, anions and cations obtained from starting neutral diradicals have been studied. Diradicals based on s-indacene and indenoacenes, with benzothiophenes fused and in different orientations, feature a varying degree of diradical character in the neutral state, which is here related with the properties of the radical redox forms. The analysis of their optical features in the polymethine monoradicals has been carried out in the framework of the molecular orbital and valence bond theories. Electronic UVVis-NIR absorption, X-ray solid-state diffraction and quantum chemical calculations have been carried out. Studies of the different positive-/negative-charged species, both residing in the same skeletal π-conjugated backbone, are rare for organic molecules. The key factor for the dual stabilization is the presence of the starting diradical character that enables to indistinctively accommodate a pseudo-hole and a pseudoelectron defect with certainly small reorganization energies for ambipolar charge transport.The authors thank the Spanish Ministry of Science and Innovation (projects MINECO/FEDER PGC2018-098533-B-100 and PID2021-127127NB-I00) and the Junta de Andalucía, Spain (UMA18FEDERJA057 and Proyecto de Excelencia PROYEXCEL- 00328). We also thank the Research Central Services (SCAI) of the University of Málaga and the US National Science Foundation (CHE-1954389 to M.M.H., CHE-2003411 to M.A. P.). F.N and Y.D. acknowledge support from “Valutazione della Ricerca di Ateneo” (VRA)-University of Bologna. Y.D. acknowledges Ministero dell’Università e della Ricerca (MUR) for her Ph.D. fellowship. Funding for open access charge: Universidad de Málaga / CBU

Statistical-mechanical formulation of Lyapunov exponents

We show how the Lyapunov exponents of a dynamic system can in general be expressed in terms of the free energy of a (non-Hermitian) quantum many-body problem. This puts their study as a problem of statistical mechanics, whose intuitive concepts and techniques of approximation can hence be borrowed.Comment: 10 pages, 3 figures, RevTex

A shot in the Dark (Ages): a faint galaxy at z=9.76z=9.76 confirmed with JWST

The appearance of galaxies over the first billion years after the Big Bang is believed to be responsible for the last dramatic change in the state of the Universe. Ultraviolet photons from galaxies within this time period - the Epoch of Reionization - ionized intergalactic Hydrogen, rendering the Universe transparent to UV radiation and ending the so-called cosmic Dark Ages, sometime after redshift $z\sim8$. The majority of ionizing photons in the first few hundred Myrs of cosmic history are thought to derive from galaxies significantly fainter than the characteristic luminosity $L^{*}$. These faint galaxies are thought to be surrounded by sufficient neutral gas to prevent the escape of the Lyman-$\alpha$ photons that would allow confirmation with current observatories. Here we demonstrate the power of the recently commissioned James Webb Space Telescope to transform our understanding of the sources of reionization, by reporting the first spectroscopic confirmation of a very low luminosity ($\sim0.05 L^{*}$) galaxy at $z=9.76$, observed 480 Myr after the Big Bang, via the detection of the Lyman-break and redward continuum with the NIRSpec and NIRCam instruments. The galaxy JD1 is gravitationally magnified by a factor of $\mu\sim13$ by the foreground cluster A2744. The power of JWST and lensing allows us to peer deeper than ever before into the cosmic Dark Ages, revealing the compact ($\sim$150 pc) and complex morphology and physical properties of an ultrafaint galaxy ($M_{\rm UV}=-17.45$).Comment: Submitted to Nature. 34 pages, 4 main figures, 1 supplementary figure, 2 supplementary tables. Comments are welcom

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Innovation-Based Remote State Estimation Secrecy with no Acknowledgments

Secrecy encoding for remote state estimation in the presence of adversarial eavesdroppers is a well studied problem. Typical existing secrecy encoding schemes rely on the transmitter's knowledge of the remote estimator's current performance. This performance measure is often shared via packet receipt acknowledgments. However, in practical situations the acknowledgment channel may be susceptible to interference from an active adversary, resulting in the secrecy encoding scheme failing. Aiming to achieve a reliable state estimate for a legitimate estimator while ensuring secrecy, we propose a secrecy encoding scheme without the need for packet receipt acknowledgments. Our encoding scheme uses a pre-arranged scheduling sequence established at the transmitter and legitimate receiver. We transmit a packet containing either the state measurement or encoded information for the legitimate user. The encoding makes the packet appear to be the state but is designed to damage an eavesdropper's estimate. The pre-arranged scheduling sequence and encoding is chosen psuedo-random. We analyze the performance of our encoding scheme against a class of eavesdropper, and show conditions to force the eavesdropper to have an unbounded estimation performance. Further, we provide a numerical illustration and apply our encoding scheme to an application in power systems.<p/