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Ultrafast Quantum Dynamics Of Doped Superfluid Helium Nanodroplets
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Book Synopsis Ultrafast quantum dynamics of doped superfluid helium nanodroplets by : François M. G. J. Coppens
Download or read book Ultrafast quantum dynamics of doped superfluid helium nanodroplets written by François M. G. J. Coppens and published by . This book was released on 2018 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dans cette thèse, nous étudions deux aspects de la dynamique d'impuretés atomiques interagissant avec des nanogouttes d'hélium superfluide (He) : la photo-excitation d'alcalins sur une nanogoutte et le dopage de nanogouttes contenant des tourbillons (vortex) quantiques avec des atomes de gaz rares. Nous utilisons la théorie de la fonctionnelle de la densité d'hélium ainsi que sa version dépendante du temps pour en faire la description théorique. Le premier aspect a été effectué dans le cadre d'une collaboration avec des expérimentateurs sur la photo-excitation du rubidium (Rb). Les alcalins sont une sonde très intéressante des gouttelettes d'hélium car ils résident dans leur zone de surface, où il a été prédit qu'un taux de condensation de Bose-Einstein de 100% était possible en raison d'une densité inférieure à celle de l'hélium superfluide. Nos simulations montrent que les états excités 5p et 6p désorbent à des échelles de temps très différentes, séparées par 2 ordres de grandeur (~100 ps et ~1 ps pour 5p et 6p respectivement). Ces résultats sont en accord avec ceux de l'expérience pompe-sonde à l'échelle femtoseconde qui a étudié la photodesorption d'atomes de Rb. Cependant, dans nos simulations, l'excitation vers 5pPi_{3/2} aboutit à un exciplexe RbHe lié à la surface, contrairement à l'expérience où RbHe est éjecté. L'introduction de la relaxation de spin de Pi_{3/2} à Pi_{1/2} nous a permis de résoudre ce désaccord, l'exciplexe RbHe ayant alors assez d'énergie pour désorber. Le deuxième aspect concerne une investigation purement théorique inspirée par les travaux récents de Gomez et Vilesov et al., où les tourbillons quantiques étaient visualisés en dopant les nanogouttes d'hélium avec des atomes d'argent, puis en les faisant atterrir en douceur (soft landing) sur un écran de carbone. Les images au microscope électronique montrent de longs filaments d'agrégats d'atomes d'argent qui s'étaient accumulés le long des coeurs des vortex. La formation de réseaux de tourbillons quantiques à l'intérieur de nanogoutelettes dopées par du xénon est également mise en évidence par diffraction de rayons X qui montrent des pics de Bragg caractéristiques d'agrégats de xénon piégés dans les coeurs des vortex. Nous avons d'abord étudié des collisions frontales entre un atome de xénon, héliophile, et une nanogoutte de 1000 héliums, et comparé les résultats à ceux d'une étude précédente sur le même processus avec le césium (Cs), qui est héliophobe. Dans le cas de Xe une «boule de neige» se forme autour de lui quand il entre dans la nanogoutte, et il lui faut beaucoup plus d'énergie qu'au Cs pour qu'il puisse en ressortir. Quand il le fait, il emporte des héliums avec lui, contrairement au Cs. Nous avons ensuite simulé des collisions entre Ar/Xe et des nanogouttes d'hélium superfluides pour différentes vitesses initiales et paramètres d'impact afin de déterminer leur section efficace de capture. Ces simulations ont ensuite été répétées pour des gouttelettes hébergeant un vortex quantique. On observe que l'impact des impuretés induit de grandes déformations de flexion et de torsion de la ligne de vortex, allant jusqu'à la génération d'ondes de Kelvin hélicoïdales qui se propagent le long du coeur du vortex. Ar/Xe est bien finalement capturé par le vortex, mais pas dans son coeur. Nous avons également découvert que l'existence d'un réseau de 6 lignes de vortex dont les noyaux sont remplis d'atomes d'Ar donne une rigidité accrue à la nanogoutte qui permet de stabiliser le système nano-goutte + vortex même à de faibles vitesses angulaires. Nos simulations impliquant des nanogouttes d'hélium comportant des tourbillons quantiques ouvrent la voie à d'autres investigations sur des nanogouttes hébergeant un ensemble de vortex, en collision avec de multiples impuretés.
Book Synopsis Molecules in Superfluid Helium Nanodroplets by : Alkwin Slenczka
Download or read book Molecules in Superfluid Helium Nanodroplets written by Alkwin Slenczka and published by Springer Nature. This book was released on 2022-05-28 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book covers recent advances in experiments using the ultra-cold, very weakly perturbing superfluid environment provided by helium nanodroplets for high resolution spectroscopic, structural and dynamic studies of molecules and synthetic clusters. The recent infra-red, UV-Vis studies of radicals, molecules, clusters, ions and biomolecules, as well as laser dynamical and laser orientational studies, are reviewed. The Coulomb explosion studies of the uniquely quantum structures of small helium clusters, X-ray imaging of large droplets and electron diffraction of embedded molecules are also described. Particular emphasis is given to the synthesis and detection of new species by mass spectrometry and deposition electron microscopy.
Book Synopsis Ultrafast dynamics in helium nanodroplets probed by XUV spectroscopy and x-ray imaging by : Camila Bacellar C Silveira
Download or read book Ultrafast dynamics in helium nanodroplets probed by XUV spectroscopy and x-ray imaging written by Camila Bacellar C Silveira and published by . This book was released on 2005 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Helium nanodroplets are the smallest known objects exhibiting superfluidity, and they provide a unique cryogenic matrix for high-resolution spectroscopy and ultracold chemistry applications. The relatively simple electronic structure of helium atoms and the homogeneity of the quantum fluid clusters make them excellent model systems for the study of electronic structures and dynamics in complex systems and the emergence of collective phenomena. Coupled electronic-nuclear dynamics in laser-excited helium nanodroplets are studied in the time-domain in two distinctly different excitation regimes following either single XUV-photon excitation or strong-field ionization by a near-infrared (NIR) laser pulse. Femtosecond time- resolved XUV photoelectron spectroscopy and femtosecond time-resolved X-ray coherent diffractive imaging are employed to monitor electronic relaxation dynamics in neutral droplets and the emergence and evolution of a nanoplasma in strong-field ionized droplets, respectively. Electronically excited pure and doped He droplets are prepared using femtosecond XUV pump pulses produced by high-order harmonic generation. The excited states and subsequent relaxation dynamics are probed by ionization of transient species with a femtosecond UV probe- pulse. Pump-probe time delay-dependent photoelectron kinetic energy distributions are measured using velocity map imaging. In pure droplets excited with 23.7 eV, three dynamic pathways are identified: interband relaxation from the initially excited 1s3p,1s4p manifold to the 1s2p band, further relaxation within the 1s2p Rydberg band and rapid atomic reconfiguration involving formation of Rydberg-excited (Hen)* cores within the droplet. Ongoing efforts towards understanding energy- and charge-transfer mechanisms between the host droplets and dopant atoms are discussed. New high-harmonic generation schemes were implemented in order to directly access the lower 1s2p droplet resonances. Droplets doped with a small amounts of Kr and Ne atoms (ndopant/ndroplet
Book Synopsis Theoretical Reaction and Relaxation Dynamics in Superfluid Helium Nanodroplets by : Miquel Blancafort Jorquera
Download or read book Theoretical Reaction and Relaxation Dynamics in Superfluid Helium Nanodroplets written by Miquel Blancafort Jorquera and published by . This book was released on 2019 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of superfluid helium has been carried out mainly by physicists. In recent years, taking advantage of the potentialities presented by superfluid helium nanodroplets (HeNDs) as inert matrices at very low temperatures (0.37 K), the chemical community became involved in its application to high-resolution spectroscopy. More recently (early 2000s), this community began to be involved in research using HeNDs to investigate chemical reactivity in this quantum solvent. As for the theoretical studies on the dynamics of physicochemical processes in HeNDs, they have been possible about five years ago and the number of theoretical dynamics studies, despite their interest, is very scarce. The main objective of this thesis is to contribute to the development of the research in this area.To introduce the reader into the topic, Chapter 1 is divided into four sections: the first one describes the properties of helium, the second one considers the history of the discovery and research carried out on the superfluidity phenomenon, the third one outlines the properties of superfluid helium nanodroplets, and the last one gives an overview of the applications and fields of study implying HeNDs.The theoretical and numerical methods used to describe superfluid liquid helium are detailed in Chapter 2. In the first section attention has been paid on the density functional theory (DFT) and its time dependent extension for real-time simulations (TDDFT). The second section describes the main density functionals used and the third section is aimed to present the numerical methods employed to perform the TDDFT calculations.The following four chapters contain the original studies carried out in this thesis. The investigation of the capture process of a Ne atom by a HeND can be found in Chapter 3. Here, the atom is treated using classical mechanics and the influence of energy and angular momentum is examined for a wide set of initial conditions. The microscopic mechanism, energy and angular momentum exchanges and vortex formation have been extensively analysed. The present contribution corresponds to the first systematic analysis of the influence of angular momentum in the capture process and vortex formation.Chapter 4 represents a natural evolution from Chapter 3 and describes the formation of a neon dimer or neon adduct inside a superfluid helium nanodroplet, treating both atoms classically. Analogously as in the previous chapter, angular momentum has also been taken into consideration and the mechanism, energy an angular momentum exchanges and vortex formation are analysed. These two chapters complement and extend two previous investigations of our group where the Ne atoms were treated using standard quantum mechanics at zero angular momentum. The contents of Chapter 4 correspond to the second theoretical investigation on bimolecular reaction dynamics in HeNDs.The following two chapters use a full quantum hybrid approach to explore rotational and vibrational energy relaxation dynamics. Chapter 5 corresponds to the first theoretical study reported so far on the rotational energy relaxation dynamics of molecules in HeNDs. This process has been studied using several isotopes of the H2 molecule (fast rotors) and considering a set of initial excitations and nanodroplet sizes.The last investigation (Chapter 6) is centred on the study of the vibrational energy relaxation in HeNDs. Thus, the influence of the energy gap between the vibrational levels, molecule-helium interaction energy and nanodroplet size on the vibrational relaxation dynamics has been analysed, taking as a reference the I2@(4He)100 doped nanodroplet which was recently studied in our group. To the best of our knowledge it is the first time that the influence of these key factors has been examined.Finally, in Chapters 7 and 8 the main conclusions and a summary in Catalan are presented.
Download or read book Nanodroplets written by Zhiming M. Wang and published by Springer Science & Business Media. This book was released on 2014-01-08 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanodroplets, the basis of complex and advanced nanostructures such as quantum rings, quantum dots and quantum dot clusters for future electronic and optoelectronic materials and devices, have attracted the interdisciplinary interest of chemists, physicists and engineers. This book combines experimental and theoretical analyses of nanosized droplets which reveal many attractive properties. Coverage includes nanodroplet synthesis, structure, unique behaviors and their nanofabrication, including chapters on focused ion beam, atomic force microscopy, molecular beam epitaxy and the "vapor-liquid- solid" route. Particular emphasis is given to the behavior of metallic nanodroplets, water nanodroplets and nanodroplets in polymer and metamaterial nanocomposites. The contributions of leading scientists and their research groups will provide readers with deeper insight into the chemical and physical mechanisms, properties, and potential applications of various nanodroplets.
Book Synopsis Ultrafast Dynamics in Helium Nanodroplets Probed by Femtosecond Time-resolved EUV Photoelectron Imaging by :
Download or read book Ultrafast Dynamics in Helium Nanodroplets Probed by Femtosecond Time-resolved EUV Photoelectron Imaging written by and published by . This book was released on 2010 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of electronically excited helium nanodroplets are studied by femtosecond time-resolved photoelectron imaging. EUV excitation into a broad absorption band centered around 23.8 eV leads to an indirect photoemission process that generates ultraslow photoelectrons. A 1.58 eV probe pulse transiently depletes the indirect photoemission signal for pump-probe time delays
Download or read book Superfluids written by Fritz London and published by . This book was released on 1961 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Imaging the Shapes and Dynamics of Superfluid Helium Nanodroplets by : Bruno Langbehn
Download or read book Imaging the Shapes and Dynamics of Superfluid Helium Nanodroplets written by Bruno Langbehn and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantum Dynamics of Ultrafast Chemical Processes by : Raffaele Borrelli
Download or read book Quantum Dynamics of Ultrafast Chemical Processes written by Raffaele Borrelli and published by . This book was released on 2003 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ultrafast Electronic Dynamics in Unipolar N-doped InGaAs/GaAs Self-Assembled Quantum Dots by : Zong-Kwei J. Wu
Download or read book Ultrafast Electronic Dynamics in Unipolar N-doped InGaAs/GaAs Self-Assembled Quantum Dots written by Zong-Kwei J. Wu and published by . This book was released on 2006 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: We presented a comprehensive picture of electron dynamics in the unipolar quantum dot structure. Although the phonon bottleneck is circumvented with high doped electron density, relaxation processes in unipolar quantum dots have been measured with time scales longer than that of bipolar systems. The results explain the operation principles of the quantum dot infrared photodetector on a microscopic level and provide basic understanding for future applications and designs.
Book Synopsis Quantum Collisions and Confinement of Atomic and Molecular Species, and Photons by : P. C. Deshmukh
Download or read book Quantum Collisions and Confinement of Atomic and Molecular Species, and Photons written by P. C. Deshmukh and published by Springer Nature. This book was released on 2019-09-28 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises selected peer-reviewed papers presented at the 7th Topical Conference of the Indian Society of Atomic and Molecular Physics, jointly held at IISER Tirupati and IIT Tirupati, India. The contributions address current topics of interest in atomic and molecular physics, both from the theoretical and experimental perspective. The major focus areas include quantum collisions, spectroscopy of atomic and molecular clusters, photoionization, Wigner time delay in collisions, laser cooling, Bose-Einstein condensates, atomic clocks, quantum computing, and trapping and manipulation of quantum systems. The book also discusses emerging topics such as ultrafast quantum processes including those at the attosecond time-scale. This book will prove to be a valuable reference for students and researchers working in the field of atomic and molecular physics.
Book Synopsis Handbook of Nanophysics by : Klaus D. Sattler
Download or read book Handbook of Nanophysics written by Klaus D. Sattler and published by CRC Press. This book was released on 2016-04-19 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the 1990s, nanoparticles and quantum dots began to be used in optical, electronic, and biological applications. Now they are being studied for use in solid-state quantum computation, tumor imaging, and photovoltaics. Handbook of Nanophysics: Nanoparticles and Quantum Dots focuses on the fundamental physics of these nanoscale materials and struct
Book Synopsis Low Temperatures and Cold Molecules by : Ian W. M. Smith
Download or read book Low Temperatures and Cold Molecules written by Ian W. M. Smith and published by Imperial College Press. This book was released on 2008 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together, for the first time, the results of recent research in areas ranging from the chemistry of cold interstellar clouds (10-20 K), through laboratory studies of the spectroscopy and kinetics of ions, radicals and molecules, to studies of molecules in liquid helium droplets, to attempts to create molecular (as distinct from atomic) Bose-Einstein condensates.
Book Synopsis Molecular Spectroscopy and Quantum Dynamics by : Roberto Marquardt
Download or read book Molecular Spectroscopy and Quantum Dynamics written by Roberto Marquardt and published by Elsevier. This book was released on 2020-09-18 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Spectroscopy and Quantum Dynamics, an exciting new work edited by Professors Martin Quack and Roberto Marquardt, contains comprehensive information on the current state-of-the-art experimental and theoretical methods and techniques used to unravel ultra-fast phenomena in atoms, molecules and condensed matter, along with future perspectives on the field. Contains new insights into the quantum dynamics and spectroscopy of electronic and nuclear motion Presents the most recent developments in the detection and interpretation of ultra-fast phenomena Includes a discussion of the importance of these phenomena for the understanding of chemical reaction dynamics and kinetics in relation to molecular spectra and structure
Download or read book Cold Chemistry written by Olivier Dulieu and published by Royal Society of Chemistry. This book was released on 2017-12-06 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent years have seen tremendous progress in research on cold and controlled molecular collisions, both in theory and in experiment. The advent of techniques to prepare cold and ultracold molecules and ions, to store them in optical lattices or in charged quasicristalline structures, and to use them in crossed or merged beam experiments have opened many new possibilities to study the most fundamental aspects of molecular interactions. At the same time, theoretical work has made progress in tackling these problems and accurately describing quantum effects in complex systems, and in proposing viable options to control chemical reactions at ultralow energies. Through tutorials on both the theoretical and experimental aspects of research in cold and ultracold molecular collisions, this book provides advanced undergraduate students, graduate students and researchers with the foundations needed to understand this exciting field.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Academies of Sciences, Engineering, and Medicine Publisher :National Academies Press ISBN 13 :0309499542 Total Pages :315 pages Book Rating :4.3/5 (94 download)
Book Synopsis Manipulating Quantum Systems by : National Academies of Sciences, Engineering, and Medicine
Download or read book Manipulating Quantum Systems written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2020-09-14 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of atomic, molecular, and optical (AMO) science underpins many technologies and continues to progress at an exciting pace for both scientific discoveries and technological innovations. AMO physics studies the fundamental building blocks of functioning matter to help advance the understanding of the universe. It is a foundational discipline within the physical sciences, relating to atoms and their constituents, to molecules, and to light at the quantum level. AMO physics combines fundamental research with practical application, coupling fundamental scientific discovery to rapidly evolving technological advances, innovation and commercialization. Due to the wide-reaching intellectual, societal, and economical impact of AMO, it is important to review recent advances and future opportunities in AMO physics. Manipulating Quantum Systems: An Assessment of Atomic, Molecular, and Optical Physics in the United States assesses opportunities in AMO science and technology over the coming decade. Key topics in this report include tools made of light; emerging phenomena from few- to many-body systems; the foundations of quantum information science and technologies; quantum dynamics in the time and frequency domains; precision and the nature of the universe, and the broader impact of AMO science.
