Laser-Induced Electron Diffraction in Chiral Molecules

Strong laser pulses enable probing molecules with their own electrons. The oscillating electric field tears electrons off a molecule, accelerates them, and drives them back toward their parent ion within a few femtoseconds. The electrons are then diffracted by the molecular potential, encoding its structure and dynamics with angstrom and attosecond resolutions. Using elliptically polarized laser pulses, we show that laser-induced electron diffraction is sensitive to the chirality of the target. The field selectively ionizes molecules of a given orientation and drives the electrons along different sets of trajectories, leading them to recollide from different directions. Depending on the handedness of the molecule, the electrons are preferentially diffracted forward or backward along the light propagation axis. This asymmetry, reaching several percent, can be reversed for electrons recolliding from two ends of the molecule. The chiral sensitivity of laser-induced electron diffraction opens a new path to resolve ultrafast chiral dynamics

Shaped liquid drops generate MeV temperature electron beams with millijoule class laser

MeV temperature electrons are typically generated at laser intensities of 1018 W cm−2. Their generation at non-relativistic intensities (~1016 W cm−2) with high repetition rate lasers is cardinal for the realization of compact, ultra-fast electron sources. Here we report a technique of dynamic target structuring of micro-droplets using a 1 kHz, 25 fs, millijoule class laser, that uses two collinear laser pulses; the first to create a concave surface in the liquid drop and the second, to dynamically-drive electrostatic plasma waves that accelerate electrons to MeV energies. The acceleration mechanism, identified as two plasmon decay instability, is shown to generate two beams of electrons with hot electron temperature components of 200 keV and 1 MeV, respectively, at an intensity of 4 × 1016 Wcm−2, only. The electron beams are demonstrated to be ideal for single shot high resolution (tens of μm) electron radiography

Laser structured micro-targets generate MeV electron temperature at 4 x10^16 W/cm^2

Relativistic temperature electrons higher than 0.5 MeV are generated typically with laser intensities of about 10^18 W/cm^2. Their generation with high repetition rate lasers that operate at non-relativistic intensities (~10^16W/cm^2) is cardinal for the realization of compact, ultra-short, bench-top electron sources. New strategies, capable of exploiting different aspects of laser-plasma interaction, are necessary for reducing the required intensity. We report here, a novel technique of dynamic target structuring of microdroplets, capable of generating 200 keV and 1 MeV electron temperatures at 1/100th of the intensity required by ponderomotive scaling(10^18 W/cm^2) to generate relativistic electron temperature. Combining the concepts of pre-plasma tailoring, optimized scale length and micro-optics, this method achieves two-plasmon decay boosted electron acceleration with "non-ideal" ultrashort (25 fs) pulses at 4 x10^16 W/cm^2 only. With shot repeatability at kHz, this precise in-situ targetry produces directed, imaging quality beam-like electron emission up to 6 MeV with milli-joule class lasers, that can be transformational for time-resolved, microscopic studies in all fields of science

Shaped liquid drops generate MeV temperature electron beams with millijoule class laser

MeV temperature electrons are typically generated at laser intensities of 1018 W cm−2. Their generation at non-relativistic intensities (~1016 W cm−2) with high repetition rate lasers is cardinal for the realization of compact, ultra-fast electron sources. Here we report a technique of dynamic target structuring of micro-droplets using a 1 kHz, 25 fs, millijoule class laser, that uses two collinear laser pulses; the first to create a concave surface in the liquid drop and the second, to dynamically-drive electrostatic plasma waves that accelerate electrons to MeV energies. The acceleration mechanism, identified as two plasmon decay instability, is shown to generate two beams of electrons with hot electron temperature components of 200 keV and 1 MeV, respectively, at an intensity of 4 × 1016 Wcm−2, only. The electron beams are demonstrated to be ideal for single shot high resolution (tens of μm) electron radiography

Mesure et contrôle de l'interaction lumière-matière chirale à l'échelle attoseconde.

Chiral molecules exist as two mirror forms, so-called enantiomers, which haveessentially the same physical and chemical properties and can only be distinguished via theirinteraction with a chiral system, such as circularly polarized light. Many biological processesare chiral-sensitive and unraveling the dynamical aspects of chirality is of prime importancefor chemistry, biology and pharmacology. Studying the ultrafast electron dynamics of chiralprocesses requires characterization techniques at the attosecond timescale. The thesis aimsat developing new approaches to measure and manipulate chiral lightmatter interaction usingthe three pillars of attosecond science: high-order harmonic generation, photoionization, andtransient absorption.Les molécules chirales existent sous deux formes images mirroir, appelées énantiomères, qui ont les mêmes propriétés physiques et chimiques et ne peuvent être distinguées que via leur interaction avec un autre système chirale, comme de la lumière polarisée circulairement. De nombreux processus biologiques sont chiro-sensibles, et élucider les aspects dynamiques de la chiralité est d’importance primordiale pour la chimie, la biologie et la pharmacologie. L’étude des processus chiraux ultrarapides nécessite de nouvelles techniques expérimentales à l’échelle attoseconde. L’objectif de cette thèse sera de développer de nouvelles approches pour mesurer et contrôler l’interaction lumière-matière chirale en utilisant les trois pilliers de la science attoseconde: la génération d’harmoniques d’ordre élevé, la photoionisation, et l’absorption transitoire

Measuring and manipulating chiral light-matter interaction on the attosecond timescale

Les molécules chirales existent sous deux formes images mirroir, appelées énantiomères, qui ont les mêmes propriétés physiques et chimiques et ne peuvent être distinguées que via leur interaction avec un autre système chirale, comme de la lumière polarisée circulairement. De nombreux processus biologiques sont chiro-sensibles, et élucider les aspects dynamiques de la chiralité est d’importance primordiale pour la chimie, la biologie et la pharmacologie. L’étude des processus chiraux ultrarapides nécessite de nouvelles techniques expérimentales à l’échelle attoseconde. L’objectif de cette thèse sera de développer de nouvelles approches pour mesurer et contrôler l’interaction lumière-matière chirale en utilisant les trois pilliers de la science attoseconde: la génération d’harmoniques d’ordre élevé, la photoionisation, et l’absorption transitoire.Chiral molecules exist as two mirror forms, so-called enantiomers, which haveessentially the same physical and chemical properties and can only be distinguished via theirinteraction with a chiral system, such as circularly polarized light. Many biological processesare chiral-sensitive and unraveling the dynamical aspects of chirality is of prime importancefor chemistry, biology and pharmacology. Studying the ultrafast electron dynamics of chiralprocesses requires characterization techniques at the attosecond timescale. The thesis aimsat developing new approaches to measure and manipulate chiral lightmatter interaction usingthe three pillars of attosecond science: high-order harmonic generation, photoionization, andtransient absorption

Mesure et contrôle de l'interaction lumière-matière chirale à l'échelle attoseconde.

Chiral molecules exist as two mirror forms, so-called enantiomers, which haveessentially the same physical and chemical properties and can only be distinguished via theirinteraction with a chiral system, such as circularly polarized light. Many biological processesare chiral-sensitive and unraveling the dynamical aspects of chirality is of prime importancefor chemistry, biology and pharmacology. Studying the ultrafast electron dynamics of chiralprocesses requires characterization techniques at the attosecond timescale. The thesis aimsat developing new approaches to measure and manipulate chiral lightmatter interaction usingthe three pillars of attosecond science: high-order harmonic generation, photoionization, andtransient absorption.Les molécules chirales existent sous deux formes images mirroir, appelées énantiomères, qui ont les mêmes propriétés physiques et chimiques et ne peuvent être distinguées que via leur interaction avec un autre système chirale, comme de la lumière polarisée circulairement. De nombreux processus biologiques sont chiro-sensibles, et élucider les aspects dynamiques de la chiralité est d’importance primordiale pour la chimie, la biologie et la pharmacologie. L’étude des processus chiraux ultrarapides nécessite de nouvelles techniques expérimentales à l’échelle attoseconde. L’objectif de cette thèse sera de développer de nouvelles approches pour mesurer et contrôler l’interaction lumière-matière chirale en utilisant les trois pilliers de la science attoseconde: la génération d’harmoniques d’ordre élevé, la photoionisation, et l’absorption transitoire

Measuring and manipulating chiral light-matter interaction on the attosecond timescale

Les molécules chirales existent sous deux formes images mirroir, appelées énantiomères, qui ont les mêmes propriétés physiques et chimiques et ne peuvent être distinguées que via leur interaction avec un autre système chirale, comme de la lumière polarisée circulairement. De nombreux processus biologiques sont chiro-sensibles, et élucider les aspects dynamiques de la chiralité est d’importance primordiale pour la chimie, la biologie et la pharmacologie. L’étude des processus chiraux ultrarapides nécessite de nouvelles techniques expérimentales à l’échelle attoseconde. L’objectif de cette thèse sera de développer de nouvelles approches pour mesurer et contrôler l’interaction lumière-matière chirale en utilisant les trois pilliers de la science attoseconde: la génération d’harmoniques d’ordre élevé, la photoionisation, et l’absorption transitoire.Chiral molecules exist as two mirror forms, so-called enantiomers, which haveessentially the same physical and chemical properties and can only be distinguished via theirinteraction with a chiral system, such as circularly polarized light. Many biological processesare chiral-sensitive and unraveling the dynamical aspects of chirality is of prime importancefor chemistry, biology and pharmacology. Studying the ultrafast electron dynamics of chiralprocesses requires characterization techniques at the attosecond timescale. The thesis aimsat developing new approaches to measure and manipulate chiral lightmatter interaction usingthe three pillars of attosecond science: high-order harmonic generation, photoionization, andtransient absorption

Constructing New Asymptotically de-Sitter Cosmological Solutions in (2+1)-Dimensions

In this work we find novel warped Kerr-de Sitter cosmological solution to the Einsteins field equa- tions in ( 2 + 1 ) − dimensions, modified by a Chern-Simons term. To start with we review the exact solutions of Einsteins field equations including the Penrose diagrams for highly symmetric space- times like that of Minkowski, de Sitter, anti-de Sitter and FLRW spacetimes. Next we review BTZ Black hole and their geometry for both rotating and non-rotating black holes. Balasubramanian and et. al. had found topologically non-trivial de Sitter (dS) solutions in (2 + 1)- dimensions, which are dubbed Kerr de Sitter and singular de Sitter quotients with Big bang/big crunch type singularities are also reviewed. Gravity in ( 2 + 1 ) − dimensions is reviewed as a simpler warm up problem to the ( 3 + 1 ) − dimensional case. In ( 2 + 1 ) − dimensions an additional Chern-Simon term is added to the Einstein-Hilbert action, this produces new interesting solutions. The introduction of the Chern-Simons term results in the non-zero mass of the graviton, thus giving us topologically massive gravity solutions. The warped AdS 3 and warped dS 3 spaces are also reviewed together with spacelike stretched warped AdS 3 black holes. Finally we write down the\ud war ped Kerr − dS 3 solutions to the topological massive gravity(TMG) equation of motion

Interaction of Tungsten tips with Laguerre-Gaussian beams

Interaction of femtosecond laser pulses with metallic tips have been studied extensively and they have proved to be a very good source of ultrashort electron pulses. We present our study of interaction of Laguerre-Gaussian (LG) laser modes with Tungsten tips. We report a change in the order of the interaction for LG beams and the difference in the order of interaction is attributed to ponderomotive shifts in the energy levels corresponding to the enhanced near field intensity supported by numerical simulations