Attosecond dynamics through a Fano resonance: Monitoring the birth of a photoelectron

This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science on 354, 11 november 2016, DOI: 10.1126/science.aah5188The dynamics of quantum systems are encoded in the amplitude and phase of wave packets. However, the rapidity of electron dynamics on the attosecond scale has precluded the complete characterization of electron wave packets in the time domain. Using spectrally resolved electron interferometry, we were able to measure the amplitude and phase of a photoelectron wave packet created through a Fano autoionizing resonance in helium. In our setup, replicas obtained by two-photon transitions interfere with reference wave packets that are formed through smooth continua, allowing the full temporal reconstruction, purely from experimental data, of the resonant wave packet released in the continuum. In turn, this resolves the buildup of the autoionizing resonance on an attosecond time scale. Our results, in excellent agreement with ab initio time-dependent calculations, raise prospects for detailed investigations of ultrafast photoemission dynamics governed by electron correlation, as well as coherent control over structured electron wave packetsWe thank S. Weber for crucial contributions to the PLFA attosecond beamline, D. Cubaynes, M. Meyer, F. Penent, J. Palaudoux, for setup and test of the electron spectrometer, and O. Smirnova, for fruitful discussions. Supported by ITN-MEDEA 641789, ANR-15-CE30-0001-01-CIMBAAD, ANR11-EQPX0005-ATTOLAB, the European Research Council Advanced Grant XCHEM no. 290853, the European COST Action XLIC CM1204, and the MINECO Project no. FIS2013-42002-R. We acknowledge allocation of computer time from CCC-UAM and Mare Nostrum BS

En filière fromagère AOP, les conditions de production dans les cahiers des charges et leurs conséquences pour les exploitations

National audienceOne of the basic problems with the 'Protected Labels of Origin' is the link between the product and the environment. In cheeses, this link is via the feeding of the dairy animals and involves the questioning of the global conditions of milk production. For the production and processing of cheeses, a synthetic approach has been chosen regarding dairying, that combines scientific data and common-sense data. The definition of these conditions rests on the aptitude of those involved in the cheese production of following together with discernment the history of the product and of its production. The producers with a 'Protected Label of Origin' are presented with proposed operational sequences that are not always without technical risks. The consideration of all the production conditions described in the 32 revised specifications for cow, ewe or goat cheeses clearly shows the convergence of the chosen regulations and the reaffirmed place of grass in the forage systems. Three operational sequences are given a detailed analysis.Une des questions fondamentales posée aux AOC est le lien entre le produit et son milieu. Pour les fromages, ce lien passe obligatoirement par l'alimentation du troupeau laitier et, par conséquent, par un questionnement sur les conditions globales de production du lait. Les liens de causes à effets entre l'alimentation et les caractéristiques du produit AOC sont cependant difficiles à établir, et les filières fromagères optent pour une approche systémique des conditions de production laitière qui intègre à la fois des données scientifiques et des données de bon sens. La définition de ces conditions repose également sur un "savoir-établir" des professionnels des filières qui assurent collectivement une lecture sélective de l'histoire du produit et de sa production. Les filières AOP proposent ainsi aux producteurs des parcours techniques originaux présentant parfois des risques techniques qui interpellent le corpus technique et scientifique. L'examen des conditions de production décrites dans les 32 cahiers des charges révisés des filières fromagères au lait de vache, de brebis et de chèvre fait apparaître une convergence des règles choisies, avec un certain nombre de pratiques "piliers" des AOP et une affirmation de la place de l'herbe dans les systèmes fourragers. L'analyse dans le détail de trois filières ou types de filières fromagères AOC (Saint-Nectaire, Epoisses et les filières des Alpes du Nord) permet d'illustrer les processus qui sous-tendent la construction et la mise en place des conditions de production dans les cahiers des charges ainsi que les effets de ces choix au niveau des exploitations et de la zone sur le court et le moyen terme

Two-dimensional phase cartography for high-harmonic spectroscopy

International audienceExtremely nonlinear spectroscopy based on high-order-harmonic generation has become a powerful investigation method for attosecond dynamics in gas and solid targets. In particular, the phase of harmonic emission was shown to carry profound insight into atomic and molecular structure and dynamics. However, current techniques offer phase measurements only along specific directions, thus providing partial characterization. Here we report on a new approach combining optical and quantum interferometers measuring along two dimensions the intensity and phase of harmonic emission from aligned molecules in the exact same experimental conditions. This two-dimensional cartography technique measures the phase with no arbitrary offset and no uncertainty on its sign. Measurements along different dimensions can be combined in two ways: either a single mapping or a redundant mapping allowing high-precision phase recovery using a Shack-Hartmann-like algorithm. We demonstrate both methods in a nitrogen test case, which allows disentangling structural and dynamical effects. Two-dimensional phase cartography paves the way to highresolution high-harmonic spectroscopy for applications such as quantum orbital tomography and attosecond charge migration in molecules

Two-dimensional phase cartography for high-harmonic spectroscopy

Extremely nonlinear spectroscopy based on high-order-harmonic generation has become a powerful investigation method for attosecond dynamics in gas and solid targets. In particular, the phase of harmonic emission was shown to carry profound insight into atomic and molecular structure and dynamics. However, current techniques offer phase measurements only along specific directions, thus providing partial characterization. Here we report on a new approach combining optical and quantum interferometers measuring along two dimensions the intensity and phase of harmonic emission from aligned molecules in the exact same experimental conditions. This two-dimensional cartography technique measures the phase with no arbitrary offset and no uncertainty on its sign. Measurements along different dimensions can be combined in two ways: either a single mapping or a redundant mapping allowing high-precision phase recovery using a Shack–Hartmann-like algorithm. We demonstrate both methods in a nitrogen test case, which allows disentangling structural and dynamical effects. Two-dimensional phase cartography paves the way to high-resolution high-harmonic spectroscopy for applications such as quantum orbital tomography and attosecond charge migration in molecules

Análise Energética da cultura do crambe (Crambe abyssinica hochst) produzida em plantio direto Analysis of Energy in the crambe culture (Crambe abyssinica hochst) produced in no tillage

O objetivo deste trabalho foi caracterizar o consumo de energia na implantação e condução da cultura do Crambe abyssinica Hochst, em sistema de plantio direto, na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas - UNESP, localizada no município de Botucatu - SP. Avaliando a sustentabilidade do sistema, estimaram-se, a eficiência energética e a cultura do crambe. Para o levantamento dos componentes da estrutura de dispêndios, foram utilizados coeficientes energéticos preconizados em literaturas especializadas. As estruturas de dispêndios energéticos por tipo, fonte e forma demonstraram que a energia indireta participou com 65,03%; as fontes industrial, fóssil e biológica representaram 68,80%, 23,67% e 11,30%, respectivamente. Quanto às formas em que se apresentaram, os fertilizantes químicos contribuíram com 44,31%, e o óleo diesel, com 23,04%, totalizando 67,35% do dispêndio energético, evidenciando a dependência do sistema das fontes energéticas industriais e fósseis. A eficiência da cultura encontrada foi de 9,98, apontando que, para cada unidade calórica aplicada na produção do crambe, o retorno foi de 8,98 unidades, a eficiência energética foi superior a 38, demonstrando alta sustentabilidade do sistema agrícola, tendo atingido energia cultural superior a 37 mil MJ ha-1.<br>The objective of this study was to characterize the energy consumption in the deployment and conduction of the culture of Crambe abyssinica Hochst in no-tillage, at the Experimental Farm belonging to the Faculty of Agronomic Sciences - UNESP, located in Botucatu - SP, Brazil. Assessing the sustainability of the system were estimated, energy efficiency and culture of crambe. To survey the components of the structure of expenditures, it was used Energetic coefficients in specialized literature. The structures of energy expenditure by type, source and form, demonstrated that the indirect energy participated with 65.03%, industrial sources, fossil and biological accounted for 68.80%, 23.67% and 11.30%, respectively. The forms have been introduced; chemical fertilizers contributed 44.31% and diesel to 23.04% to 67.35% of energy expenditure, showing the dependence of the system of energy sources and industrial fuels. The efficiency of the culture was found to be 9.98, indicating that for each calorie used in the production of crambe return was 8.98 units, the efficiency was above 38, demonstrating the high sustainability of the agricultural system to reach energy cultural exceeding 37 thousand MJ ha-1