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

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

Statistiques

Nombre de fichiers déposés

43

Nombre de notices déposées

79