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

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

Statistiques

Nombre de fichiers déposés

43

Nombre de notices déposées

79