Infrared spectral fingerprint of neutral and charged endo- and exohedral metallofullerenes

Small metal-containing molecules have been detected and recognized as one of the hybrid species efficiently formed in space; especially in the circumstellar envelopes of evolved stars. It has been predicted also that more complex hybrid species like those formed by metals and fullerenes (metallofullerenes) could be present in such circumstellar environments. Recently, quantum-chemical simulations of metallofullerenes have shown that they are potential emitters contributing to the observed mid-IR spectra in the fullerene-rich circumstellar environments of different types of evolved stars. Here we present the individual simulated mid-IR (~5-50 um) spectra of twenty-eight metallofullerene species; both neutral and charged endo- and exohedral metallofullerenes for seven different metals (Li, Na, K, Ca, Mg, Ti, and Fe) have been considered. The changes induced by the metal-C60 interaction on the intensity and position of the spectral features are highlighted using charge density difference maps and electron density partitioning. Our calculations identify the fundamental IR spectral regions where, depending on the metal binding nature, there should be a major spectral contribution from each of the metallofullerenes. The metallofullerenes IR spectra are made publicly available to the astronomical community, especially James Webb Space Telescope users, for comparisons that could eventually lead to the detection of these species in space.Comment: Accepted for publication in The Astrophysical Journal Supplement Series on 19 September 2023 (in press) (13 pages, 7 figures, and 1 table

Decay pathways for protonated and deprotonated adenine molecules

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Chemical Physics 151.4 (2019): 044306 and may be found at https://aip.scitation.org/doi/abs/10.1063/1.5109963We have measured fragment mass spectra and total destruction cross sections for protonated and deprotonated adenine following collisions with He at center-of-mass energies in the 20-240 eV range. Classical and ab initio molecular dynamics simulations are used to provide detailed information on the fragmentation pathways and suggest a range of alternative routes compared to those reported in earlier studies. These new pathways involve, for instance, losses of HNC molecules from protonated adenine and losses of NH2 or C3H2N2 from deprotonated adenine. The present results may be important to advance the understanding of how biomolecules may be formed and processed in various astrophysical environmentsThis work was supported by the Swedish Research Council (Constant Nos. 2017-00621, 2015-04990, 2016-04181, and 2018-04092). Furthermore, we acknowledge the European Joint on Theoretical Chemistry and Computational Modelling (INT-EJD-TCCM). We acknowledge the generous allocation of computer time at the Centro de Computacion Cientifica at the Universidad Autonoma de Madrid (CCC-UAM). This work was partially supported by Project No. CTQ2016-76061-P of the Spanish Ministerio de Economia y Competitividad (MINECO

Confinment of the image potential states inside vacancy islands in the 1ML

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Different quantization behavior of electrons confined in nanostructures at surfaces

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Theoretical study of electron confinement in Cu corrals on a Cu(111) surface

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Electron propagation along Cu nanowires supported on a Cu(111) surface.

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Ecologically sustainable life and ethics : a biography of José Lutzenberger

Esta tese visa a construção de uma biografia histórica do engenheiro agrônomo e ambientalista José Lutzenberger (1926-2002). O objetivo é compreender de que maneira a trajetória de Lutzenberger se articula com a construção de uma ética ecológica, em meio às lutas que ele protagonizou ao longo de trinta e um anos de militância ambiental. O fio condutor da narrativa é a ética ecológica, pois foi o elemento central em seu trabalho, que orientava sua própria visão de como o mundo deveria ser se a humanidade adotasse uma postura que priorizasse a ecologia. Utilizou-se, entre outros acervos, principalmente documentação do Arquivo Privado de José Lutzenberger (APJL): correspondência, recortes de jornais e revistas, iconografia, obras de Lutzenberger e de terceiros, documentos pessoais e oficiais, textos de depoimentos, conferências e de entrevistas, charges, textos técnicos. Também fizemos uso de fontes orais. A tese está estruturada em oito capítulos, de acordo com as lutas e posições ocupadas por Lutzenberger, ao longo de sua trajetória, enfocando as principais campanhas ambientalistas em que se envolveu, o cargo de Secretário de Meio Ambiente no governo Collor, sua atuação como empresário de “tecnologias suaves”, seu trabalho com educação ambiental e agricultura ecológica. O trabalho também analisa as redes de relações tecidas pelo personagem e a abordagem teórica em que se embasou para criar sua ética ecológica, de caráter ecocêntrico. Foi possível avançar no entendimento do arcabouço intelectual de Lutzenberger, bem como na dinâmica de sua militância, oferecendo uma sistematização dos princípios do que chamamos a Ética Lutzenbergeriana, ou Ética do convívio ecossustentável.This dissertation aims at constructing a historical biography of José Lutzenberger, agronomist and environmental engineer (1926-2002). This biography aids in observing how his trajectory is articulated with the construction of an ecological ethics amidst his protagonism in 31 years of environmental militancy. Ecological ethics conduces this narrative as this was the central element in his work, guiding his own view of how the world should be if Humanity adopted a posture that prioritized Ecology. The main documental source was his private archive (Arquivo Privado de José Lutzenberger - APJL). Other sources used were correspondence, news clippings, iconography, works by Lutzenberger and others, personal and official documents, textual testimonials, conferences and interviews, editorial cartoons, and technical texts. Oral sources have also been used. The 8-chapter structure of this dissertation delineates the positions occupied by Lutzenberger and his trajectory of fight, with focus on the main environmentalist campaigns with which he was involved, as well as his position as Secretary of the Environment during the Collor administration, his business in "soft technology", his work with ecological agriculture and environmental education. This study also presents analysis of the networks created around him, as well as the theoretical bases he used to create the ecological ethics with its eco-centric character. Advances in the understanding of Lutzenberger's intellectual outlines and of the dynamics of his militancy in this work offer a systematization of principles named the Lutzenbergerian Ethics, or the Ethics of Eco-sustainable Life

Fragmentation of hydrocarbons by collision. AGAT@ANDROMEDE.

International audienceWe are studying small hydrocarbons produced in high velocity (3.4 a.u.) collision between ${{\rm{CH}}}_{y}^{+}$ cations and He atoms. During the collision those hydrocarbons gain some energy and release this energy doing fragmentation. Thanks to the detector AGAT we have been able to measure fragmentation branching ratios for ${{\rm{CH}}}_{y}^{q+}$ (y=2-4, q=0-3). We also constructed semi-empirical breakdown curves for ${{\rm{CH}}}_{y}^{q+}$ using these experimental branching ratios