index - Femto Accéder directement au contenu

Derniers dépôts, tout type de documents

We study optical field emission from silver nanotips, showing the combined influence of the illumination wavelength and the exact shape of the nanotip on the strong-field response. This is particularly relevant in the case of FIB milled nano tips, where the nanotip fabrication capabilities could become a new ingredient for the study of strong-field physics. The influence of the thermal load on the nanotip and its effect on the emission is studied as well by switching the repetition rate of the laser source from 1 kHz to 62 MHz, showing a clear transition towards the quenching of the strongfield emission.

Continuer la lecture Partager

Bell's inequality violation experiments are becoming increasingly popular in the practical teaching of undergraduate and master's degree students. Bell's parameter S is obtained from 16 polarization correlation measurements performed on entangled photons pairs. We first report here a detailed analysis of the uncertainty u(S) of Bell's parameter taking into account coincidence count statistics and errors in polarizers' orientation. We show using both computational modeling and experimental measurement that the actual sequence of the polarizer settings has an unexpected and strong influence on the error budget. This result may also be relevant to measurements in other settings in which errors in parameters may have non-random effects in the measurement.

Continuer la lecture Partager

We report results of experimental investigation of field electron emission from diamond nanoemitters. The measurements were performed with single crystal diamond needles fixed at tungsten tips. The voltage drop along diamond needles during emission was revealed and measured using electron energy spectroscopy. The observed linear dependence of the voltage drop in diamond on voltage applied to the tungsten tip is explained in the frame of a simple macroscopic electrical model combining Poole–Frenkel conduction along the diamond tip and Fowler–Nordheim tunneling at the diamond-vacuum junction. Experimental evidences of electron emission sensitivity to laser illumination are discussed for possible modification of diamond emitter characteristics and voltage drop.

Continuer la lecture Partager

High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using ​SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20–26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected.

Continuer la lecture Partager

Sujets

Femtosecond pulse Cold field emission Emission par champ froid Oscillations de Rabi Photoémission Ultraviolet 4230Kq Azoture de chlore Number theory C2H2 Couplage spatio-temporel AOPDF Chlorine azide Pump-probe ClN3 Interférences de chemins quantiques CYCLIC-N-3 Quantum path interferences CIN3 Factorization Complete characterization Extreme ultraviolet Rubidium atom ATOMS Gauss sums XUV Ultrafast nonlinear optics Coherent Transient Spin-orbit precession Diffractive optical element Ultrashort pulses Photoemission Contrôle cohérent Adiabatic rapid passage Expériences pompe-sonde Chirped pulses Contrôle spatio-temporel 4265Re Coherent pulse propagation Passage adiabatique rapide Wave packet interferences Characterisation Coherent Transients Excited states sodium Femtosecond lasers Echantillon multidiffusant Optical Parametric Amplifier CHARGE-TRANSFER Dynamique moléculaire Mise en forme d'impulsions Molecular dynamics 7867Pt Coherent control Femtoseconde Time-resolved photoelectron spectroscopy Anharmonicity Caractérisation Quantum dots Chirped laser pulses Attoseconde ENERGY 4265Ky Pulse shaping Impulsions à dérive de fréquence ALIGNED MOLECULES Femtosecond spectroscopy CHLORINE AZIDE 4225Ja Velocity map imaging Caractérisation spatio-temporelle Bell's inequality Boîte quantique semiconductrice Caractérisation complète Ultrashort lasers Femtosecond Factorisation Cold Molecules Transitoires cohérents Femtosecond pulses Half revival Attosecond NO2 Atom-photon collisions Chirp modulation rotational states quantum theory energy level crossing laser beams dissociation Femtochemistry Acétylène Autocorrelation function Mise en forme d'impulsion 7960Jv Rabi oscillations Azulene Femtosecond laser Champ fort Génération d'harmoniques d'ordre élevé Diamond nanotip Quantum state measurement Expérience pompe-sonde Cold molecules ELEMENTAL FRACTIONATION Coherent transients

Statistiques

Chargement de la page

Nombre de fichiers déposés

Chargement de la page

Nombre de notices déposées

79