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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.

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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.

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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.

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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.

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Sujets

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

Statistiques

Nombre de fichiers déposés

43

Nombre de notices déposées

79