Search results for " resolve"
showing 10 items of 75 documents
Quantum correlation of electron and ion energy in the dissociative strong-field ionization of H2
2023
We report on the strong field ionization of H2 by a corotating two-color laser field. We measure the electron momentum distribution in coincidence with the kinetic energy release (KER) of dissociating hydrogen molecules. In addition to a characteristic half-moon structure, we observe a low-energy structure in the electron momentum distribution at a KER of about 3.5 eV. We speculate that the outgoing electron interacts with the molecular ion, despite the absence of classical recollisions under these conditions. Time-dependent density functional theory simulations support our conclusions.
First-principles modelling for time-resolved ARPES under different pump-probe conditions
2021
First-principles methods for time-resolved angular resolved photoelectron spectroscopy play a pivotal role in providing interpretation and microscopic understanding of the complex experimental data and in exploring novel observables or observation conditions that may be achieved in future experiments. Here we describe an efficient, reliable and scalable first-principles method for tr-ARPES based on time-dependent density functional theory including propagation and surface effects usually discarded in the widely used many-body techniques based on computing the non-equilibrium spectral function and discuss its application to a variety of pump–probe conditions. We identify four conditions, dep…
Bridging Sensing and Decision Making in Ambient Intelligence Environments
2009
Context-aware and Ambient Intelligence environments represent one of the emerging issues in the last decade. In such intelligent environments, information is gathered to provide, on one hand, autonomic and easy to manage applications, and, on the other, secured access controlled environments. Several approaches have been defined in the literature to describe context-aware application with techniques to capture and represent information related to a specified domain. However and to the best of our knowledge, none has questioned the reliability of the techniques used to extract meaningful knowledge needed for decision making especially if the information captured is of multimedia types (image…
Femtosecond Raman time-resolved molecular spectroscopy
2004
International audience; The applicability of several femtosecond time resolved non-linear coherent techniques such as Raman induced polarization spectroscopy (RIPS), degenerate four-wave mixing (DFWM) and coherent anti-Stokes Raman spectroscopy (CARS) for molecular spectroscopy is presented. All methods rely on the initial coherent excitation of molecular states producing wavepackets, whose time evolution is then measured. In the case of RIPS and DFWM only pure rotational transitions are involved, whereas in CARS vibrational states can be excited. First the methodology of concentration and temperature measurements using RIPS in gas mixtures involving N2, CO2, O2, and N2O is shown. In additi…
A new method for the study of antiparallel ferroelectric domains
1992
Abstract Beam-coupling topography is a non-destructive holographic technique for spatially resolved recording of hysteresis loops and for imaging of domains. Its basic principle is interference of rays diffracted from a holographic grating with collinear, transmitted ones. Full domain contrast and noise suppression is achieved by appropriate control of intensity and phase of the interfering beams. The method is applied to antiparallel a-domains in (Sr0.61Ba0.39)Nb2O6:Ce.
Environmental Stewardship, Moral Psychology and Gardens
2013
Vast and pervasive environmental problems such as climate change and biodiversity loss call every individual to active stewardship. Their magnitude and causal and strategic structures, however, pose powerful challenges to our moral psychology. Stewardship may feel overburdening, and appear hopeless. This may lead to widespread moral and political disengagement. This article proposes a resolve to garden practices as a way out of that danger, and describes the ways in which it will motivate individuals to so act as to coordinate on behavioural patterns that will significantly alleviate grave, but seemingly distant and intractable environmental quandaries.
Spatially resolved SO2 flux emissions from Mt Etna
2016
We report on a systematic record of SO2 flux emissions from individual vents of Etna volcano (Sicily), which we obtained using a permanent UV camera network. Observations were carried out in summer 2014, a period encompassing two eruptive episodes of the New South East Crater (NSEC) and a fissure-fed eruption in the upper Valle del Bove. We demonstrate that our vent-resolved SO2 flux time series allow capturing shifts in activity from one vent to another and contribute to our understanding of Etna's shallow plumbing system structure. We find that the fissure eruption contributed ~50,000 t of SO2 or ~30% of the SO2 emitted by the volcano during the 5 July to 10 August eruptive interval. Acti…
Bright Visible Luminescence in Silica Nanoparticles
2011
International audience; We demonstrate that a porous film of silica nanoparticles emits a bright visible luminescence associated with defects stabilized by oxygen chemisorption at oxygen deficient center sites. Time-resolved spectra excited by a tunable laser allow us to distinguish the luminescence at 1.99 eV, characteristic of the nonbridging oxygen hole center (NBOHC) (Si-O)3 Si-O*, and a fast and a slow emission: the first (lifetime τ ≈ 25 ns) is peaked at 2.27 eV with an excitation spectrum centered at 5.5 eV; the second (τ ≈ 7.5 μs) is peaked at 2.41 eV and is excited around 3.2 and 5.2 eV. Reaction in an air atmosphere leads to the disappearance of the NBOHC luminescence and of the …
Alignment of linear molecules by short duration laser pulses
2005
Alignment of linear molecules is efficiently induced by strong linearly polarized laser pulses. In the case of short pulses with respect to molecular rotation, periodic alignment appears in field-free conditions after the extinction of the field. This manuscript presents three techniques where the value of allows to quantify alignment without molecular dissociation nor additional alignment. They use a weak time-delayed probe pulse which experiences the optical properties of an aligned sample and shows modification of its characteristics. The first of them measures a depolarization due to the birefringence of the sample. The second one is based on the defocusing produced by the spatial distr…
Sobre la identidad y procedencia del poeta Filóxeno y la autoría del ditirambo ???????
2019
El presente estudio pretende resolver la controversia en torno a la identidad y procedencia del poeta Filóxeno, célebre ditirambógrafo del siglo V-IV a.C. Para ello, hemos recopilado todos los testimonios que citan a personajes con el nombre de Filóxeno desde la primera mención de Aristófanes. La investigación ha revelado que existen varios individuos con el mismo nombre y rasgos comunes. No obstante, el examen de estos testimonios revela la existencia de un único autor de ditirambos: Filóxeno de Citera. Además, creemos que este poeta fue el autor del ditirambo ???????, que algunos editores atribuyeron falsamente a Filóxeno de Léucade. Posteriormente, reflexionamos sobre la identidad de Fil…