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Synthesis of N-Methyl- and N,N-Dimethylmerucathine and of N-Methyl- and N,N--Dimethylpseudomerucathine Starting from L-Alanine Starting form L-alanine, N-methylmerucathine (= (3R,4S)-4-(methylamino)1-phenyl-1-penten-3-ol; (3R,4S,)-6), N,N-dimethylmerucathine (= (3R,4S)-4-(dimethylamino)-1-phenyl-1-penten-3-ol; (3R,4S)-9), N-methylpseudomerucathine (= (3S,4S)-4-(methylamino)-1-phenyl-1-penten-3-01; (3S,4S)-6), and N,N-dimethylpseudomerucathine (= (3S,4S)-4-(dimethylamino)-1-phenyl-1-penten-3-ol; (3S,4S)-9) were synthesized. The four compounds were analyzed by HPLC and compared with a natural khat extract.

Synthesis and Structure Elucidation of Merucathinone and Synthesis of Cathinone. Constituents of Catha edulis FORSK. Starting from L-alanine, two constituents of Catha edulis FORSK., (S)-4-amino-1-phenylpent-1-en-3-on ((S)-3; merucathinone) and (S)-2-amino-1-phenylpropan-1-on ((S)-1; cathinone) were synthesized.

En politique de développement, la discussion sur les stratégies d’industrialisation compte parmi les thèmes les plus anciens et les activités dans le secteur artisanal/industriel font partie du répertoire classique de l’aide au développement. Toutefois, ce n’est que vers les années 1980 qu’un regain d’intérêt de la part des organismes de développement se manifeste et que leurs efforts porteront prioritairement sur ce secteur. Il va sans dire que la situation économique difficile de la plupart des pays en développement, la croissance de leur endettement et l’augmentation du chômage sont des raisons suffisantes pour favoriser et encourager le secteur clef qu’est la promotion artisanale et industrielle.L’objectif de cet article est de présenter, d’une part, les activités typiques menées par les organisations suisses à la promotion de l’artisanat et de l’industrie dans le cadre de la coopération au développement et, d’autre part, de montrer au lecteur les dimensions de l’enjeu de cette promotion.Dans le chapitre introductif, la promotion artisanale/industrielle est placée dans son contexte historique. Suit un inventaire des différentes notions utilisées pour désigner les sous-secteurs qui font l’objet de ces interventions promotionnelles.Le deuxième chapitre présente les activités dans le secteur artisanal/industriel de cinq agents de coopération au développement. Il s’agit de la DDA, Swisscontact, Swissaid, FUNDES et le bureau de l’ONUDI à Zurich. Cette présentation est suivie d’une comparaison montrant les différences et ressemblances des activités menées par les organismes sélectionnés.Les questions méritant une réflexion approfondie sur les résultats escomptés de la promotion du secteur artisanal/industriel font l’objet du troisième chapitre. Il s’agit de questions relatives au type de relations entre les sous-secteurs de l’économie ; aux différentes conceptions de la gestion d’entreprise ; à la participation des bénéficiaires, aux choix des technologies et aux influences conjoncturelles sur les résultats de la promotion.

C45-and C50-Carotenoids: Synthesis of (S)-Trisanhydrobacterioruberin The Synthesis of (S)-trisanhydrobacterioruberin ((S)-1) is reported.

The temperatures of sputtered alkali-metal dimers have been measured using one- and two-photon ionization spectroscopy. They are estimated to be 1470 +- 300 K, 1025 +- 200 K, and 1000 +- 200 K for Cs/sub 2/, K/sub 2/, and Na/sub 2/, respectively. The vibrational and rotational temperatures are found to be very similar. No dependence of the dimer excitation is found, neither on target temperature nor on the primary-ion energy. The results are compared with some currently used models to explain cluster formation in sputtering experiments.

Des dipeptides proteges, enantiomeriquement purs, Val-Ala, Ile-Ala et β-methylLeu-Ala ont ete prepares regioselectivement a partir de l'acide-N-[phenyl-9 fluorenyl-9] aspartique

Synthesis of ‘D-Isothreonine’ and ‘L-Alloisothreonine’ Starting from L-Alanine Starting from L-alanine, ‘D-isothreonine’ ( = (2R, 3S)-3-amino-2-hydroxybutanoic acid) and ‘L-alloisothreonine’ ( = (2S, 3S)-3-amino-2-hydroxybutanoic acid) were synthesized.

The excitation spectrum of Na3 was systematically investigated from 700 to 330 nm. Four excited states were observed. One of them exhibits fractional quantization of the vibronic pseudorotation which constitutes the first direct verification of the adiabatic sign-change theorem. Photofragmentation is studied by depletion spectroscopy and the 420 nm system is found to be completely predissociated. The structure of the ground state and the ionization potential are also measured.

Synthesis and Structure Elucidation of Merucathine and Pseudomerucathine. Two Constituents of Catha edulis FORSK. Starting from L-alanine, two constituents of Catha edulis FORSK. (3R,4S)-4-amino-1-phenyl-1-penten-3-ol ((3R,4S)-4, merucathine) and (3S,4S)-4-amino-1-phenyl-1-penten-3-ol ((3S,4S)-4, pseudomerucathine) were synthesized.

The vibronic level spectrum of the ground state of the alkali trimer Na3 has been observed via stimulated emission spectroscopy of a supercooled metal cluster beam. Results reported herein use the C state as an intermediate, and reveal strong transitions to combinations of the symmetric stretch and bending modes, along with highly detailed fine structure.

The excitation spectrum of Na3 was systematically investigated from 700 to 330 nm. Four excited states were observed. One of them exhibits fractional quantization of the vibronic pseudorotation which constitutes the first direct verification of the adiabatic sign-change theorem. Photofragmentation is studied by depletion spectroscopy and the 420 nm system is found to be completely predissociated. The structure of the ground state and the ionization potential are also measured.

The spectroscopy of Na3 has been systematically investigated with different techniques: Two-Photon Ionization (TPI) and Depletion Spectroscopy (DS). Four excited electronic states have been found in the range from 850 nm to 330 nm. The lifetime measurement of these states suggests that the highly excited ones are partially or totally predissociated. For this reason depletion spectroscopy has been used, and reveals the complete structure of the predissociated C-state. The Na3 ground state has been investigated by hot band analysis. This allows a precise comparison with the calculations.

The spectroscopy of Na3 has been systematically investigated with three different techniques: two-photon ionization (TPI), depletion spectroscopy (DS), and stimulated emission pumping (SEP). Four excited electronic states have been found in the range from 850 nm to 330 nm. The lifetime measurement of these states suggests that the highly excited ones are partially or totally predissociated. For this reason depletion spectroscopy has been used, and reveals the complete structure of the predissociated C-state. The Na3 ground state has been investigated using stimulated emission pumping. This allows a precise comparison with the calculations.

Inner-shell autoionization spectra obtained with synchrotron radiation are reported for mercury clusters ${\mathrm{Hg}}_{n}$, $n\ensuremath{\le}40$. For the small clusters $n\ensuremath{\le}12$ the spectral behavior as a function of size is interpreted in terms of an excitonic model. For larger cluster sizes a gradual deviation from van der Waals bonding is observed. The asymmetry occuring in the line profiles reflects the progressive construction of the $\mathrm{sp}$ conduction band.

The optical Kerr response of hydrogen atom submitted to a strong and short near infrared laser pulse excitation is studied by solving the full 3D time-dependent Schro¨dinger equation. The nonlinear polarization evaluated at the driving field frequency is compared to the canonical expression derived from perturbation theory. A discrepancy between the two models is observed at large intensity affecting the nonlinear propagation of short and intense laser pulses.

We show the first results of a linear 100-micromirror array capable of modulating the phase and amplitude of the spectral components of femtosecond lasers. Using MEMS-based reflective systems has the advantage of utilizing coatings tailored to the laser wavelength range. The innovative features of our device include a novel rotational, vertical comb-drive actuator and an X-shaped, laterally reinforced spring that prevents lateral snap-in while providing flexibility in the two degrees of freedom of each mirror, namely piston and tilt. The packaging utilizes high-density fine-pitch wire-bonding for on-chip and chip-to-PCB connectivity. For the first deployment, UV-shaped pulses will be produced to coherently control the dynamics of biomolecules.

This review provides a comprehensive overview of the structural dynamics in topical gas- and condensed-phase systems on multiple length and time scales. Starting from vibrationally induced dissociation of small molecules in the gas phase, the question of vibrational and internal energy redistribution through conformational dynamics is further developed by considering coupled electron/proton transfer in a model peptide over many orders of magnitude. The influence of the surrounding solvent is probed for electron transfer to the solvent in hydrated I−. Next, the dynamics of a modified PDZ domain over many time scales is analyzed following activation of a photoswitch. The hydration dynamics around halogenated amino acid side chains and their structural dynamics in proteins are relevant for iodinated TyrB26 insulin. Binding of nitric oxide to myoglobin is a process for which experimental and computational analyses have converged to a common view which connects rebinding time scales and the underlying dynamics. Finally, rhodopsin is a paradigmatic system for multiple length- and time-scale processes for which experimental and computational methods provide valuable insights into the functional dynamics. The systems discussed here highlight that for a comprehensive understanding of how structure, flexibility, energetics, and dynamics contribute to functional dynamics, experimental studies in multiple wavelength regions and computational studies including quantum, classical, and more coarse grained levels are required.

In this contribution we present the review of recent experimental and numerical investigations in a very new research field of nonlinear optics - interaction of high energy femtosecond mid-infrared laser pulses with matter. Following current developments in the field of optical parametric chirped pulse amplification (OPCPA) we have designed a sub-terawatt OPCPA laser system delivering 10 mJ, 80 fs pulses at the central wavelength of 3.9 μm [1]. Using this unique laser system, a large number of experiments on the interaction of high intensity mid-IR laser pulses with gases and solids were carried out. We show that even in the case of collimated beam propagation of high power mid-IR radiation in air is accompanied by highly nonlinear interaction with the gas which includes not only the lowest for centrosymmetric media third order nonlinearity but also higher fifth and seventh order contributions. Soft focusing of the mid-IR beam in gases leads to the generation of multiple optical harmonics (Fig. 1a) which opens new perspectives for nonlinear molecular spectroscopy. By increasing the gas pressure, filamentation of the mid-IR femtosecond laser pulses was demonstrated and investigated for the first time. In atomic gases like argon, an impressive super-continuum, spanning over three octaves, is generated (Fig. 1b). We show that this continuum builds-up via the efficient generation of low-order harmonics and cascaded four-wave mixing processes [2]. In molecular gases, efficient continuum generation further in the mid-IR spectral range is demonstrated (Fig. 1b), revealing important role of stimulated Raman scattering in filament dynamics.

Significant efforts have been dedicated to control lightning with lasers [1] to protect sensitive sites like rocket launching pads and airports. We report on a dedicated European large framework project towards this goal, called Laser Lightning Rod (llr-fet.eu) [2] . In this project, a unique laser system has been developed, providing 720 mJ, < 1 picosecond pulses at 1 kHz repetition rate, i.e., TW-class peak power and kW average power [3] . This thin disk laser has been further frequency doubled (SHG) and tripled (THG) to provide high intensity outputs at 1030 nm, 515 nm and 343 nm, with conversion efficiencies up to 45% and 30%, respectively. Nonlinear propagation and filamentation of this laser could be characterized over 130 meters in a dedicated hall (LAL in Orsay), both in a collimated geometry, and using a 40 cm diameter beam expander. The whole system will be transported to the top of the Santis Mountain (2481 m altitude) in Switzerland in April 2021, one of the locations with the highest lightning occurrence in Europe. The site has been fully equipped to host the laser transmitter in the harsh meteorological conditions encountered on the top of the mountain. The site has also been fully equipped with state of the art lightning detection and measurement devices (a lightning mapping array, an interferometer, high-speed cameras, current sensors, a field mill, etc.) to register the triggering and guiding effects of the laser on the lightning process. This site is especially interesting as it generates mostly upward flashes from the 123 m tall tower communications tower. The laser will be aimed to the top of this tower in order to extend its height by the length of the filaments , realizing a "laser lightning rod".

We show that the onset of laser multiple filamentation can be described as a critical phenomenon that we characterize both experimentally and numerically by measuring a set of seven critical exponents. This phase transition deviates from any existing universality class, and offers a unique perspective of conducting two-dimensional experiments of statistical physics at a human scale., 8 pages, 9 figures

We present experimental and numerical investigation of multi-millijoule mid-IR supercontinuum generation by mid-IR femtosecond filaments in molecular gases. Drastic difference in spectra between atomic and molecular gases and crucial role of Raman scattering is demonstrated.

A pump-probe two-photon-excited fluorescence technique deciphers in space and time the propagation of ballistic wave packets sustained by whispering-gallery modes (WGMs) in a spiral-shaped microcavity. Diffraction on the spiral discontinuity does not prevent the WGMs from closing. The resultant average Q of the resonator is 3 x 10(4) +/- 50%. Experimental results are compared with numerical simulations, providing evidence of a new contribution to output coupling: Part of the WGM evanescent wave is reflected at the spiral notch and leads to a propagating wave at an angle that matches the previously observed laser emission direction in 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran-doped poly(methyl methacrylate) and InGaN spiral lasers.

Numerous symptoms have been associated with the overtraining syndrome (OT), including changes in autonomic function. Heart rate variability (HRV) provides non-invasive data about the autonomic regulation of heart rate in real-life conditions. The aims of the study were to: (i) characterize the HRV profile of seven athletes (OA) diagnosed as suffering of OT, compared with eight healthy sedentary (C) and eight trained (T) subjects during supine rest and 60 degrees upright, and (ii) compare the traditional time- and frequency-domain analysis assessment of HRV with the non-linear Poincare plot analysis. In the latter each R-R interval is plotted as a function of the previous one, and the standard deviations of the instantaneous (SD1) and long-term R-R interval variability are calculated. Total power was higher in T than in C and OA both in supine (1158 +/- 1137, 6092 +/- 3554 and 2970 +/- 2947 ms2 for C, T and OA, respectively) and in upright (640 +/- 499, 1814 +/- 806 and 1092 +/- 712 ms2 for C, T and OA, respectively; P

We demonstrate that a highly confined plasma inclusion is formed inside a micrometric water droplet that is excited by a femtosecond laser. An 800-nm laser pulse generates a plasma inclusion by laser-induced breakdown that is subsequently probed by the elastic scattering of a second (400-nm) time-delayed ultrashort pulse. For a 25-microm-radius droplet and an incident intensity of 7 x 10(12) W/cm2 the radius of the highly localized plasma is 1.9 +/- 0.4 microm. We probed the plasma formation dynamics on femtosecond time scales by varying the delay between the pump and the probe pulses. Good agreement with numerical simulations of the process was found.

Electric currents circulating between charged clouds and the earth surface during lightning discharges are responsible for considerable damages and casualties. It is therefore important to develop better protection methods in addition to the traditional Franklin rod. Here we present the first demonstration that filaments formed by short and intense laser pulses can guide lightning discharges over considerable distances. We believe that this experimental breakthrough will lead to progress in lightning protection and lightning physics. An experimental campaign was carried out on the S\"antis Mountain in Northeastern Switzerland during the Summer of 2021 with a high repetition rate terawatt laser. The guiding of an upward negative lightning leader over a distance of 50 m was recorded by two separate high-speed cameras. The guiding of negative lightning leaders by laser filaments was corroborated in three other instances by VHF interferometric measurements, and the number of X-ray bursts detected during guided lightning events was significantly increased. While this research field has been very active for more than 20 years with many research groups around the world working to achieve this goal, this result demonstrates lightning guiding by lasers, which may lead to the development of a laser lightning rod. This work paves the way for new atmospheric applications of ultrashort lasers and represents a significant step forward in the development of a laser based lightning protection for airports, launchpads or large infrastructures., Comment: Laser-guided lightning. Nat. Photon. (2023)

This article presents the present-day capability of three-dimensional analysis of air pollution, by both differential absorption lidar and advanced numerical models. These two techniques exhibit numerous similarities, both at the level of spatial resolution and on a working scale. Two measurement campaigns have been performed to determine emission characteristics and concentrations of sulfur dioxide (SO2) in order to illustrate these similarities. The results of the intercomparisons are satisfactory, and differences are usually within 20%.

The addition rate constants of five differently substituted benzoyl radicals to butyl acrylate were determined by continuous-wave time-resolved EPR (TR-EPR at X-band (9 GHz) and at W-band (95 GHz)) spectroscopy. Remarkably, the reactivity of the benzoyl radicals, is divided into two domains: One is established at low (

Laser filaments interacting with cirrus like ice crystals produce a large number of small secondary ice particles by re-condensation of the released water vapor. This new phenomenon drastically modifies its radiative forcing

We report a new differential absorption lidar technique for measuring simultaneously the concentrations of NO and NO(2) in the atmosphere. The technique is based on the correlation of the 450-nm absorption band of NO(2) and 227-nm absorption band of NO by frequency doubling. This performance has been allowed by the advent of a new and highly efficient frequency doubling crystal: the beta-BaB(2)O(4). A test experiment on a NO/NO(2) emitter has been performed, demonstrating the efficiency of the technique. The detection limit is estimated to be ~1 ppm .m for NO(2) and 100 ppb.m for NO. The range of measurement is limited to 1 km, due to the strong UV Rayleigh scattering and O(2) absorption.

International audience; Background: Harmonic Nanoparticles are a new family of exogenous markers for multiphoton imaging exerting optical contrast by second harmonic (SH) generation. In this tutorial, we present the application of Hyper-Rayleigh Scattering (HRS) for a quantitative assessment of the nonlinear optical properties of these particles and discuss the underlying theory and some crucial experimental aspects. Methods: The second harmonic properties of BaTiO3, KNbO3, KiTiOPO4 (KTP), LiNbO3 and ZnO nanocrystals (NCs) are investigated by HRS measurements after careful preparation and characterization of colloidal suspensions. Results: A detailed analysis of the experimental results is presented with emphasis on the theoretical background and on the influence of some experimental parameters including the accurate determination of the nanocrystal size and concentration. The SH generation efficiency and averaged nonlinear optical coefficients are then derived and compared for six different types of NCs. Conclusions: After preparation of colloidal NC suspensions and careful examination of their size, concentration and possible aggregation state, HRS appears as a valuable tool to quantitatively assess the SH efficiency ofnoncentrosymmetric NCs. All the investigated nanomaterials show high SH conversion efficiencies, demonstrating a good potential for bio-labelling applications.

Non-centrosymetric nanocrystals show promising nonlinear optical properties for being used as optical labels in bio-imaging applications, with significant interest for observations of long duration and for penetration depth into biological tissues. The development of such biomarkers requires the determination of their nonlinear optical properties to select the best potential markers. In this thesis, Hyper-Rayleigh Scattering (HRS) technique is used to determine nonlinear efficiencies of several nanocystals (BaTiO3, KNbO3, KTP, LiNbO3, ZnO and BiFeO3). These ensemble measurements have been performed on nanocrystals suspensions, for which the influence of parameters such as size, concentration and aggregation state was discussed. BiFeO3nanocrystals offer the best nonlinear optical efficiency compared to other particles, showing their potential as efficient optical biomarkers. Polarisation-resolved measurements have also been performed to retrieve individual coefficients of the nonlinear tensor of the investigated materials and influent parameters such as nanocrystals shape have been identified.; Les nanocristaux à structure non-centrosymétrique présentent des propriétés optiques non linéaires prometteuses pour une utilisation en tant que marqueurs optiques en imagerie biomédicale, avec un intérêt significatif en termes de suivi sur de longues durées et de profondeur de pénétration dans les tissus biologiques. Le développement de ces marqueurs nécessite la détermination de leurs efficacités optiques non linéaires afin de pouvoir sélectionner les nanocristaux les plus prometteurs. Pour cela, la technique de diffusion Hyper-Rayleigh a été adaptée à la caractérisation de suspensions de nanoparticules (BaTiO3, KNbO3, KTP, LiNbO3 et ZnO, BiFeO3) pour lesquelles l’influence de paramètres comme la taille, la concentration ou l’état d’agrégation a été analysée et discutée. Les nanocristaux de BiFeO3 possèdent une efficacité optique non linéaire largement supérieure aux autres particules, démontrant leur potentiel pour la réalisation de nano-sondes optiques particulièrement performantes. Des mesures résolues en polarisation ont également été mises en œuvre pour déterminer les coefficients optiques non linéaires indépendants des particules étudiées. Dans ce cadre, une étude a permis de mettre en évidence l’influence de la forme des nanocristaux sur cette réponse.

Non-centrosymetric nanocrystals show promising nonlinear optical properties for being used as optical labels in bio-imaging applications, with significant interest for observations of long duration and for penetration depth into biological tissues. The development of such biomarkers requires the determination of their nonlinear optical properties to select the best potential markers. In this thesis, Hyper-Rayleigh Scattering (HRS) technique is used to determine nonlinear efficiencies of several nanocystals (BaTiO3, KNbO3, KTP, LiNbO3, ZnO and BiFeO3). These ensemble measurements have been performed on nanocrystals suspensions, for which the influence of parameters such as size, concentration and aggregation state was discussed. BiFeO3nanocrystals offer the best nonlinear optical efficiency compared to other particles, showing their potential as efficient optical biomarkers. Polarisation-resolved measurements have also been performed to retrieve individual coefficients of the nonlinear tensor of the investigated materials and influent parameters such as nanocrystals shape have been identified., Les nanocristaux à structure non-centrosymétrique présentent des propriétés optiques non linéaires prometteuses pour une utilisation en tant que marqueurs optiques en imagerie biomédicale, avec un intérêt significatif en termes de suivi sur de longues durées et de profondeur de pénétration dans les tissus biologiques. Le développement de ces marqueurs nécessite la détermination de leurs efficacités optiques non linéaires afin de pouvoir sélectionner les nanocristaux les plus prometteurs. Pour cela, la technique de diffusion Hyper-Rayleigh a été adaptée à la caractérisation de suspensions de nanoparticules (BaTiO3, KNbO3, KTP, LiNbO3 et ZnO, BiFeO3) pour lesquelles l’influence de paramètres comme la taille, la concentration ou l’état d’agrégation a été analysée et discutée. Les nanocristaux de BiFeO3 possèdent une efficacité optique non linéaire largement supérieure aux autres particules, démontrant leur potentiel pour la réalisation de nano-sondes optiques particulièrement performantes. Des mesures résolues en polarisation ont également été mises en œuvre pour déterminer les coefficients optiques non linéaires indépendants des particules étudiées. Dans ce cadre, une étude a permis de mettre en évidence l’influence de la forme des nanocristaux sur cette réponse.

Ultrashort laser pulses propagate in the air in the form of structures of one hundredmicrons of diameter called “filaments”, which have the properties of self-guiding, propagatingfor hundreds of meters, white light generation, etc. These original properties find severalapplications in the domain of remote sensing of pollutants by non-linear Lidar measurements,lightning control, remote LIBS, etc.During my PhD work we have performed several laboratory experiments and field campaignwithin the context of Teramobile project. In particular we have studied the geometry offilamentation, its robustness in an extended region of turbulent air, the propagation ofultrashort pulses beam in multijoules regime, and atmospheric applications of filamentation.For example, we have characterized the angular distribution of the conical emission in thevisible and ultraviolet spectral bands. In another series of experiments, we have proved thatatmospheric turbulence is not a limiting factor of filaments propagation, which also keep theirspectral properties useful for atmospheric applications. Finally, we have illustrated a methodof laser triggering and guiding of lightning and realized laser induced condensation of waterdroplets in laboratory as well as in a reel atmosphere.; La propagation des impulsions laser ultra brèves dans l’air se fait sous la forme de structures d’une centaine de micromètres de diamètre appelées filaments, qui ont entre autres les propriétés d’être autoguidées, de se propager sur plusieurs centaines de mètres, de générer un continuum de lumière blanche, etc. Ces propriétés originales trouvent de nombreuses applications dans le domaine de la télédétection des polluants par mesures lidar, le déclenchement et le guidage de la foudre par laser, le LIBS à distance, etc.Au cours de mon travail de thèse, nous avons mené de nombreuses expériences de laboratoire et sur terrain dans le cadre du projet Tera mobile. Nous avons en particulier étudié la géométrie de la filamentation, sa robustesse dans une région de turbulence étendue, la propagation verticale d’un faisceau d’impulsions ultra brèves dans un régime multi joules, et des applications atmosphériques de la filamentation. Nous avons par exemple caractérisé la distribution angulaire de l’émission conique dans le visible et dans l’ultraviolet. Nous avons également prouvé que la turbulence atmosphérique n’est pas un facteur limitant de la propagation des filaments qui arrivent même à garder leurs propriétés spectrales nécessaires aux applications atmosphériques. Enfin nous avons illustré une méthode de déclenchement et de guidage de foudre par laser et réalisé une expérience de condensation de gouttelettes d’eau assistée par laser en laboratoire ainsi que dans une atmosphère réelle.

Ultrashort laser pulses propagate in the air in the form of structures of one hundredmicrons of diameter called “filaments”, which have the properties of self-guiding, propagatingfor hundreds of meters, white light generation, etc. These original properties find severalapplications in the domain of remote sensing of pollutants by non-linear Lidar measurements,lightning control, remote LIBS, etc.During my PhD work we have performed several laboratory experiments and field campaignwithin the context of Teramobile project. In particular we have studied the geometry offilamentation, its robustness in an extended region of turbulent air, the propagation ofultrashort pulses beam in multijoules regime, and atmospheric applications of filamentation.For example, we have characterized the angular distribution of the conical emission in thevisible and ultraviolet spectral bands. In another series of experiments, we have proved thatatmospheric turbulence is not a limiting factor of filaments propagation, which also keep theirspectral properties useful for atmospheric applications. Finally, we have illustrated a methodof laser triggering and guiding of lightning and realized laser induced condensation of waterdroplets in laboratory as well as in a reel atmosphere., La propagation des impulsions laser ultra brèves dans l’air se fait sous la forme de structures d’une centaine de micromètres de diamètre appelées filaments, qui ont entre autres les propriétés d’être autoguidées, de se propager sur plusieurs centaines de mètres, de générer un continuum de lumière blanche, etc. Ces propriétés originales trouvent de nombreuses applications dans le domaine de la télédétection des polluants par mesures lidar, le déclenchement et le guidage de la foudre par laser, le LIBS à distance, etc.Au cours de mon travail de thèse, nous avons mené de nombreuses expériences de laboratoire et sur terrain dans le cadre du projet Tera mobile. Nous avons en particulier étudié la géométrie de la filamentation, sa robustesse dans une région de turbulence étendue, la propagation verticale d’un faisceau d’impulsions ultra brèves dans un régime multi joules, et des applications atmosphériques de la filamentation. Nous avons par exemple caractérisé la distribution angulaire de l’émission conique dans le visible et dans l’ultraviolet. Nous avons également prouvé que la turbulence atmosphérique n’est pas un facteur limitant de la propagation des filaments qui arrivent même à garder leurs propriétés spectrales nécessaires aux applications atmosphériques. Enfin nous avons illustré une méthode de déclenchement et de guidage de foudre par laser et réalisé une expérience de condensation de gouttelettes d’eau assistée par laser en laboratoire ainsi que dans une atmosphère réelle.

Within the general framework of the optical detection of bacteria, we implement two original methods to distinguish molecules whose optical properties are similar: femtosecond LIBS for bacteria, and coherent control for flavins.Coherent control distinction of flavins consists in 400 nm pulse shaping, and then controlling the excited state of molecules in the liquid phase by a second infrared pulse which decreases fluorescence. We bring to the fore solvent role for this two pulses process of depletion with tryptophan. Spectroscopic studies in liquid phase with intense pulses sometimes generate unexpected non-linear effects, which is at the origin of the study of the filamentation in an absorbing liquid medium.Photofragmentation of ionized biological chromophores, flavins and tryptophan, are examined in gas phase using similar ``pump-pump" scheme to the one used for depletion. We show, with flavin mononucleotide, that the second pulse decreases certain ways of fragmentation to the benefit of the others. Lastly, we reveal the potentialities of femtosecond LIBS for bacteria discrimination and foliar analysis., Dans le cadre général de la détection optique de bactéries, nous mettons en œuvre deux méthodes originales pour distinguer des molécules dont les propriétés optiques sont similaires : la LIBS femtoseconde pour les bactéries, et le contrôle cohérent pour les flavines.La distinction des flavines par contrôle cohérent consiste à façonner une impulsion excitatrice à 400 nm, et à contrôler l'état excité des molécules en phase liquide par une deuxième impulsion infrarouge qui en diminue la fluorescence. Nous mettons en évidence le rôle du solvant dans ce processus bi-impulsionnel de déplétion, pour le tryptophane. Les études spectroscopiques en phase liquide, qui utilisent des impulsions intenses, engendrent des effets non-linéaires parfois inattendus, qu'il est important de connaître : c'est pourquoi nous étudions la filamentation dans un milieu liquide absorbant.La photofragmentation des chromophores biologiques ionisés, flavines et tryptophanes, est examinée en phase gazeuse à l'aide d'un dispositif « pompe-pompe » similaire à celui de la déplétion. Nous montrons, avec la flavine mononucléotide, que la seconde impulsion diminue certaines voies de fragmentation au profit des autres. Enfin, nous révélons les potentialités de la LIBS femtoseconde pour l'analyse foliaire et la discrimination de bactéries.

Within the general framework of the optical detection of bacteria, we implement two original methods to distinguish molecules whose optical properties are similar: femtosecond LIBS for bacteria, and coherent control for flavins.Coherent control distinction of flavins consists in 400 nm pulse shaping, and then controlling the excited state of molecules in the liquid phase by a second infrared pulse which decreases fluorescence. We bring to the fore solvent role for this two pulses process of depletion with tryptophan. Spectroscopic studies in liquid phase with intense pulses sometimes generate unexpected non-linear effects, which is at the origin of the study of the filamentation in an absorbing liquid medium.Photofragmentation of ionized biological chromophores, flavins and tryptophan, are examined in gas phase using similar ``pump-pump" scheme to the one used for depletion. We show, with flavin mononucleotide, that the second pulse decreases certain ways of fragmentation to the benefit of the others. Lastly, we reveal the potentialities of femtosecond LIBS for bacteria discrimination and foliar analysis.; Dans le cadre général de la détection optique de bactéries, nous mettons en œuvre deux méthodes originales pour distinguer des molécules dont les propriétés optiques sont similaires : la LIBS femtoseconde pour les bactéries, et le contrôle cohérent pour les flavines.La distinction des flavines par contrôle cohérent consiste à façonner une impulsion excitatrice à 400 nm, et à contrôler l'état excité des molécules en phase liquide par une deuxième impulsion infrarouge qui en diminue la fluorescence. Nous mettons en évidence le rôle du solvant dans ce processus bi-impulsionnel de déplétion, pour le tryptophane. Les études spectroscopiques en phase liquide, qui utilisent des impulsions intenses, engendrent des effets non-linéaires parfois inattendus, qu'il est important de connaître : c'est pourquoi nous étudions la filamentation dans un milieu liquide absorbant.La photofragmentation des chromophores biologiques ionisés, flavines et tryptophanes, est examinée en phase gazeuse à l'aide d'un dispositif « pompe-pompe » similaire à celui de la déplétion. Nous montrons, avec la flavine mononucléotide, que la seconde impulsion diminue certaines voies de fragmentation au profit des autres. Enfin, nous révélons les potentialités de la LIBS femtoseconde pour l'analyse foliaire et la discrimination de bactéries.

We have developed a real-time optical technique that discriminates bioaerosols among urban background aerosols, especially soot emitted by diesel engines. This technique is based on the multipulse ultrashort excitation of instrinsic fluorophors of bioaerosols and identifies their molecular dynamics. Specific fingerprints of bacteria and hydrocarbons could be exhibited. This study is a first step towards the all-optical identification of biological material.Pump-probe spectroscopy has also been employed to probe the propagation dynamics of a femtosecond pulse in a 2D spiral-shaped microcavity. An imaging technique using pulse correlation has been developed to visualize with femtosecond time resolution the propagation of a wavepacket in the microcavity. FDTD simulations have enabled to interpret our observations and to exhibit an original output coupling process, that implies the reflexion of the evanecent wave on the discontinuity of the spiral., Nous avons mis au point une nouvelle technique optique de détection en temps réel des bioaérosols parmi un ensemble d'aérosols de fond, dont en particulier les suies de combustion. Cette technique repose sur l'excitation ultra-brève multi-impulsionnelle des fluorophores intrisèques des bioaérosols. Des signatures spécifiques aux bactéries et aux hydrocarbures ont ainsi été mises en évidence, alors que les spectres de fluorescence de ces espèces sont indiscernables. La spectroscopie pompe-sonde a aussi été mise en oeuvre pour sonder la dynamique de propagation d'une impulsion femtoseconde dans une microcavité 2D de forme spirale. Nous avons réalisé un dispositif d'imagerie de corrélation afin de suivre, avec une résolution temporelle, la propagation d'un paquet d'onde laser. Des simulations FDTD ont permis d'interpréter les observations et de mettre en évidence un processus original de couplage de sortie, impliquant la réflexion de l'onde évanescente sur la discontinuité de la spirale.

When ultrasshort and high-power laser pulses propagate across the atmosphere, self-guided filaments of 100 $\mu m$ radius are formed. They result from a balance between Kerr self-focusing and defocusing by the plasma generated by multiphoton ionisation.\\During my thesis, we showed that the white light spectrum generated in filament spans from the the infrared (4,5 $\mu m$) to the ultraviolet (230 nm) to thanks to Third Harmonic Generation and self-phase modulation. We charaterized the propagation under different conditions (rain, smog, turbulence) to developp different atmospheric applications. In particular, we demostrated multi-parameters LIDAR for relative humidity as well as atmospheric pollution remote sensing.\\ Furthermore, it is possible to detect and to identify biological aerosols or solid targets (LIBS) at remote distances, by non-linear processes induced {\it{in situ}} by the high intensity delivered by filaments. Moreover, we demonstrated that guiding and triggering high-voltage discharge thanks to a femsecond high-powered pulse is possible even under a rain with an efficiency comparable to that observed in dry air. We also impoved the efficiency of a two pulses configurations (a femtosecond pulse and a subsequent nanosecond pulse). These results raise hope that lightning could be triggered and guided by laser pulses in the future., Les impulsions laser ultra-brèves (fs) et ultra-intenses (TW) forment, au cours de leur propagation non-linéaire dans l'atmosphère, des structures auto-guidées, d'une centaine de microns de diamètre, appelées filaments. Ces filaments résultent d'un équilibre dynamique entre l'effet Kerr qui focalise le faisceau et la défocalisation due plasma généré au sein de ceux-ci. Au cours de mon travail de thèse, nous avons mesuré que le spectre de lumière blanche issue de l'automodulation de phase et de la génération de troisième harmonique s'étend de l'ultra-violet (230 nm) à l'infrarouge (4,5 µm). De même, la propagation dans l'air, sous différentes conditions (pluie, brouillard, turbulence), des faisceaux térawatts femtosecondes a été caractérisée afin de développer des applications atmosphériques. Il nous a ainsi été possible de développer le Lidar à lumière blanche pour réaliser des mesures préliminaires d'ozone et d'aérosols simultanément. De même, grâce à la propagation fortement non-linéaire du faisceau qui permet de transporter des hautes intensités sur de longue distance, nous avons pu détecter et identifier, à distance, des aérosols biologiques et des cibles solides (LIBS) en induisant in situ des effets non-linéaires. Enfin, nous avons montré que le déclenchement et le guidage de décharges de haute tension par une impulsion laser femtoseconde sous la pluie reste possible avec une efficacité comparable à l'atmosphère sèche. D'autre part, une configuration à double impulsion laser augmente l'efficacité de déclenchement des décharges. Ces résultats nous rapprochent de la perspective de déclenchement et guidage de foudre par laser.

The aerosols are an essential component of the urban pollution and of physico-chemistry of the atmosphere. It's of the first interest to dispose of three-dimensions concentration maps with lidar method. An original method, with one wavelength, has been developed. It's based on the impacting and study of filters and their composition. In particular, the distribution is bimodal with one mode at 20 nm and the other one around 1 μm. With our lidar, we have measured the aerosol concentration, the evolution and the stratification of the boundary layer. But, this method is heavy because of the filters study, and use as a strong hypothesis that the atmsophere is homogeneous vertically.To distinguish between the modes of the distribution and obtain an “all-optical” diagnostic, we have extend in the infrared, more sensitive to micrometer sized aerosols, the existing UV lidar system, more sensitive to the small sizes.This extension is based on optical parametric oscillators (OPO). The different crystals, capable of producing efficiently mid-infrared wavelengths, have been tested. These crystals are the KTiOPO4 (KTP), the KTiAsO4 (KTA) and the KNbO3. After that, one of these OPO has been implemented in our lidar system. Preliminary infrared lidar concentration measurements have been obtained for water droplets during a haze episode.Concurrently to the preceding linear lidar systems, a non-linear lidar project (Teramobile project) is born. A white light source, due to generated filaments in the air during terawatt laser beam propagation, is used to do multispectral aerosol lidar. With this source, from UV to mid-IR, aerosol concentration measurements will be possible without any a priori hypothesis, contrary to the preceding methods., Les aérosols sont une composante essentielle de la pollution urbaine et de la physico-chimie de l'atmosphère. Il est primordial de disposer de cartographies 3D de leur concentration par méthode lidar.Une méthode originale, à une longueur d'onde, a été développée. Elle est basée sur l'impaction et l'étude de filtres permettant d'obtenir des informations complémentaires sur la distribution de taille des aérosols et sur leur composition. Les résultats, obtenus dans l'UV montrent que la distribution a un mode pour les petites tailles (~100 nm) et un mode pour les particules plus grosses (~1 μm). Notre lidar a aussi permis de mesurer la concentration en aérosols, l'évolution et la stratification de la couche limite. Mais cette méthode reste lourde à cause de l'étude des filtres et utilise comme hypothèse forte que l'atmosphère est homogène verticalement.Pour distinguer entre les modes des particules et obtenir un diagnostique « tout-optique », nous avons étendu dans l'IR, plus sensible aux aérosols de la taille du micron, le système lidar UV existant, plus sensible aux petites tailles.Cette extension est basée sur des oscillateurs paramétriques optiques (OPO). Les différents cristaux susceptibles de produire efficacement de l'IR moyen ont été testés. Ces cristaux sont le KTiOPO4, le KTiAsO4 et le KNbO3. Puis, un de ces OPO a été implanté dans notre système lidar. Les mesures lidar préliminaires de concentration dans l'IR, ont été obtenues pour des gouttelettes d'eau lors d'un épisode de brume. Parallèlement aux systèmes lidar linéaires précédents, un projet de lidar non-linéaire (projet Teramobile), a vu le jour. Une source de lumière blanche provenant des filaments, générés dans l'air lors de la propagation d'un faisceau laser térawatt, est utilisée pour faire du lidar aérosols multispectral. Avec cette source allant de l'UV à l'IR moyen, des mesures de concentration en aérosols seront possibles sans aucune hypothèse a priori contrairement aux méthodes précédentes.

The aerosols are an essential component of the urban pollution and of physico-chemistry of the atmosphere. It's of the first interest to dispose of three-dimensions concentration maps with lidar method. An original method, with one wavelength, has been developed. It's based on the impacting and study of filters and their composition. In particular, the distribution is bimodal with one mode at 20 nm and the other one around 1 μm. With our lidar, we have measured the aerosol concentration, the evolution and the stratification of the boundary layer. But, this method is heavy because of the filters study, and use as a strong hypothesis that the atmsophere is homogeneous vertically.To distinguish between the modes of the distribution and obtain an “all-optical” diagnostic, we have extend in the infrared, more sensitive to micrometer sized aerosols, the existing UV lidar system, more sensitive to the small sizes.This extension is based on optical parametric oscillators (OPO). The different crystals, capable of producing efficiently mid-infrared wavelengths, have been tested. These crystals are the KTiOPO4 (KTP), the KTiAsO4 (KTA) and the KNbO3. After that, one of these OPO has been implemented in our lidar system. Preliminary infrared lidar concentration measurements have been obtained for water droplets during a haze episode.Concurrently to the preceding linear lidar systems, a non-linear lidar project (Teramobile project) is born. A white light source, due to generated filaments in the air during terawatt laser beam propagation, is used to do multispectral aerosol lidar. With this source, from UV to mid-IR, aerosol concentration measurements will be possible without any a priori hypothesis, contrary to the preceding methods.; Les aérosols sont une composante essentielle de la pollution urbaine et de la physico-chimie de l'atmosphère. Il est primordial de disposer de cartographies 3D de leur concentration par méthode lidar.Une méthode originale, à une longueur d'onde, a été développée. Elle est basée sur l'impaction et l'étude de filtres permettant d'obtenir des informations complémentaires sur la distribution de taille des aérosols et sur leur composition. Les résultats, obtenus dans l'UV montrent que la distribution a un mode pour les petites tailles (~100 nm) et un mode pour les particules plus grosses (~1 μm). Notre lidar a aussi permis de mesurer la concentration en aérosols, l'évolution et la stratification de la couche limite. Mais cette méthode reste lourde à cause de l'étude des filtres et utilise comme hypothèse forte que l'atmosphère est homogène verticalement.Pour distinguer entre les modes des particules et obtenir un diagnostique « tout-optique », nous avons étendu dans l'IR, plus sensible aux aérosols de la taille du micron, le système lidar UV existant, plus sensible aux petites tailles.Cette extension est basée sur des oscillateurs paramétriques optiques (OPO). Les différents cristaux susceptibles de produire efficacement de l'IR moyen ont été testés. Ces cristaux sont le KTiOPO4, le KTiAsO4 et le KNbO3. Puis, un de ces OPO a été implanté dans notre système lidar. Les mesures lidar préliminaires de concentration dans l'IR, ont été obtenues pour des gouttelettes d'eau lors d'un épisode de brume. Parallèlement aux systèmes lidar linéaires précédents, un projet de lidar non-linéaire (projet Teramobile), a vu le jour. Une source de lumière blanche provenant des filaments, générés dans l'air lors de la propagation d'un faisceau laser térawatt, est utilisée pour faire du lidar aérosols multispectral. Avec cette source allant de l'UV à l'IR moyen, des mesures de concentration en aérosols seront possibles sans aucune hypothèse a priori contrairement aux méthodes précédentes.