Ultrafast Investigation Of Electronic And Structural Dynamics In Photomagnetic Molecular Solids
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Ultrafast Investigation Of Electronic And Structural Dynamics In Photomagnetic Molecular Solids
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Author : Andrea Marino
language : en
Publisher:
Release Date : 2015
Ultrafast Investigation Of Electronic And Structural Dynamics In Photomagnetic Molecular Solids written by Andrea Marino and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The ability to photo-switch physical/chemical properties of functional materials through photo induced phase transition opens fascinating perspectives for driving the material towards new state out of thermal equilibrium. However, it is fundamental to disentangle and understand all the dynamical phenomena, otherwise hidden in statistically averaged macroscopic transformations. Arguably, time-resolved studies are unique approach to access the necessary information on the multiple degrees of freedom and elementary processes involved during the macroscopic switching. As photo-reversible molecular switches, spin crossover (SCO) materials are of particular interest. These photomagnetic and photochromic prototype materials undergo metastable photoinduced phase transition between two states of different spin multiplicity, namely low-spin (LS) and high-spin (HS). In this PhD work it will be presented the ultrafast electronic and structural dynamics of SCO molecular solids emphasizing the importance of using complementary probes sensitive to different degrees of freedom. The photoinduced spin state switching concerns initially only an ultrafast, but localized, molecular response which through strong electron-phonon coupling activates coherent intra-molecular vibrations. An ultrafast energy transfer from the molecule to the lattice, via phonon-phonon coupling, allows an efficient trapping of the system in the new photoinduced state. However in molecular solids, the excess of energy released from the absorber molecule results in a complex multi-scale aspect involving several degrees of freedom at different time scales. In this contest, we investigated the multi-step out-of equilibrium dynamics of a SCO system undergoing symmetry breaking between the HS phase and the intermediate (IP) phase where a long range ordering of HS and LS molecules results in a spin state concentration wave (SSCW), analogous to charge or spin density waves. Combined time-resolved X-ray diffraction and optical spectroscopy studies provide a complete overview of the out-of-equilibrium thermodynamics of the SSCW, investigating how the two order parameters describing the system evolve in time.
Ultrafast Electronic And Structural Dynamics In Solids
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Author : Eli Nathan Glezer
language : en
Publisher:
Release Date : 1996
Ultrafast Electronic And Structural Dynamics In Solids written by Eli Nathan Glezer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Laser pulses, Ultrashort categories.
Chemistry In Action Making Molecular Movies With Ultrafast Electron Diffraction And Data Science
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Author : Lai Chung Liu
language : en
Publisher: Springer Nature
Release Date : 2020-09-10
Chemistry In Action Making Molecular Movies With Ultrafast Electron Diffraction And Data Science written by Lai Chung Liu and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-09-10 with Science categories.
The thesis provides the necessary experimental and analytical tools to unambiguously observe the atomically resolved chemical reactions. A great challenge of modern science has been to directly observe atomic motions during structural transitions, and while this was first achieved through a major advance in electron source brightness, the information content was still limited and new methods for image reconstruction using femtosecond electron diffraction methods were needed. One particular challenge lay in reconciling the innumerable possible nuclear configurations with the observation of chemical reaction mechanisms that reproducibly give the same kind of chemistry for large classes of molecules. The author shows that there is a simple solution that occurs during barrier crossing in which the highly anharmonic potential at that point in nuclear rearrangements couples high- and low-frequency vibrational modes to give highly localized nuclear motions, reducing hundreds of potential degrees of freedom to just a few key modes. Specific examples are given in this thesis, including two photoinduced phase transitions in an organic system, a ring closure reaction, and two direct observations of nuclear reorganization driven by spin transitions. The emerging field of structural dynamics promises to change the way we think about the physics of chemistry and this thesis provides tools to make it happen.
Ultrafast Phenomena Xvii
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Author : Majed Chergui
language : en
Publisher: OUP USA
Release Date : 2011-02-10
Ultrafast Phenomena Xvii written by Majed Chergui and has been published by OUP USA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-02-10 with Science categories.
Ultrafast Phenomena XVII presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. This book summarizes the results presented at the 17th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field.
Ultrafast Structural Dynamics In Combustion Relevant Model Systems
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Author :
language : en
Publisher:
Release Date : 2014
Ultrafast Structural Dynamics In Combustion Relevant Model Systems written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The research project explored the time resolved structural dynamics of important model reaction system using an array of novel methods that were developed specifically for this purpose. They include time resolved electron diffraction, time resolved relativistic electron diffraction, and time resolved Rydberg fingerprint spectroscopy. Toward the end of the funding period, we also developed time-resolved x-ray diffraction, which uses ultrafast x-ray pulses at LCLS. Those experiments are just now blossoming, as the funding period expired. In the following, the time resolved Rydberg Fingerprint Spectroscopy is discussed in some detail, as it has been a very productive method. The binding energy of an electron in a Rydberg state, that is, the energy difference between the Rydberg level and the ground state of the molecular ion, has been found to be a uniquely powerful tool to characterize the molecular structure. To rationalize the structure sensitivity we invoke a picture from electron diffraction: when it passes the molecular ion core, the Rydberg electron experiences a phase shift compared to an electron in a hydrogen atom. This phase shift requires an adjustment of the binding energy of the electron, which is measurable. As in electron diffraction, the phase shift depends on the molecular, geometrical structure, so that a measurement of the electron binding energy can be interpreted as a measurement of the molecule's structure. Building on this insight, we have developed a structurally sensitive spectroscopy: the molecule is first elevated to the Rydberg state, and the binding energy is then measured using photoelectron spectroscopy. The molecule's structure is read out as the binding energy spectrum. Since the photoionization can be done with ultrafast laser pulses, the technique is inherently capable of a time resolution in the femtosecond regime. For the purpose of identifying the structures of molecules during chemical reactions, and for the analysis of molecular species in the hot environments of combustion processes, there are several features that make the Rydberg ionization spectroscopy uniquely useful. First, the Rydberg electron's orbit is quite large and covers the entire molecule for most molecular structures of combustion interest. Secondly, the ionization does not change vibrational quantum numbers, so that even complicated and large molecules can be observed with fairly well resolved spectra. In fact, the spectroscopy is blind to vibrational excitation of the molecule. This has the interesting consequence for the study of chemical dynamics, where the molecules are invariably very energetic, that the molecular structures are observed unobstructed by the vibrational congestion that dominates other spectroscopies. This implies also that, as a tool to probe the time-dependent structural dynamics of chemically interesting molecules, Rydberg spectroscopy may well be better suited than electron or x-ray diffraction. With recent progress in calculating Rydberg binding energy spectra, we are approaching the point where the method can be evolved into a structure determination method. To implement the Rydberg ionization spectroscopy we use a molecular beam based, time-resolved pump-probe multi-photon ionization/photoelectron scheme in which a first laser pulse excites the molecule to a Rydberg state, and a probe pulse ionizes the molecule. A time-of-flight detector measures the kinetic energy spectrum of the photoelectrons. The photoelectron spectrum directly provides the binding energy of the electron, and thereby reveals the molecule's time-dependent structural fingerprint. Only the duration of the laser pulses limits the time resolution. With a new laser system, we have now reached time resolutions better than 100 fs, although very deep UV wavelengths (down to 190 nm) have slightly longer instrument functions. The structural dynamics of molecules in Rydberg-excited states is obtained by delaying the probe ionization p ...
Synthesis And Applications Of New Spin Crossover Compounds
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Author : Takafumi Kitazawa
language : en
Publisher: MDPI
Release Date : 2019-10-11
Synthesis And Applications Of New Spin Crossover Compounds written by Takafumi Kitazawa and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-10-11 with Science categories.
The crystal chemistry of spin crossover (SCO) behavior in coordination compounds can potentially be in association with smart materials—promising materials for applications as components of memory devices, displays, sensors and mechanical devices and, especially, actuators, such as artificial muscles. This Special Issue is devoted to various aspects of SCO and related research, comprising 18 interesting original papers on valuable and important SCO topics. Significant and fundamental scientific attention has been focused on the SCO phenomena in a wide research range of fields of fundamental chemical and physical and related sciences, containing the interdisciplinary regions of chemical and physical sciences related to the SCO phenomena. Coordination materials with bistable systems between the LS and the HS states are usually triggered by external stimuli, such as temperature, light, pressure, guest molecule inclusion, soft X-ray, and nuclear decay. Since the first Hofmann-like spin crossover (SCO) behavior in {Fe(py)2[Ni(CN)4]}n (py = pyridine) was demonstrated, this crystal chemistry motif has been frequently used to design Fe(II) SCO materials to enable determination of the correlations between structural features and magnetic properties.
Atomistic Spin Dynamics
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Author : Olle Eriksson
language : en
Publisher: Oxford University Press
Release Date : 2017
Atomistic Spin Dynamics written by Olle Eriksson and has been published by Oxford University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Science categories.
The purpose of this book is to provide a theoretical foundation and an understanding of atomistic spin-dynamics (ASD), and to give examples of where the atomistic Landau-Lifshitz-Gilbert equation can and should be used. As argued in the text, a description of magnetism in an atomistic way is very natural and allows for an interpretation of experimental results in a clear and deep way. This description also allows for calculations, from first principles, of all parameters needed to perform the spin-dynamics simulations, without using experimental results as input to the simulations. As shown in the book, we are now at a very exciting situation, where it is possible to perform accurate and efficient atomistic simulations on a length- and time-scale which is balancing on the edge of what is experimentally possible. In this way, ASD simulations can both validate and be validated by state-of-the art experiments, and ASD simulations also have the possibility to act as a predictive tool that is able to explain the magnetization dynamics in experimentally inaccessible situations. The purpose of this book has been to communicate technically relevant concepts. An even larger motivation is to communicate an inspiration to magnetism and magnetization dynamics, and the emerging technological fields that one may foresee, e.g. in magnonics, solitonics and skyrmionics.
Handbook Of Spintronics
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Author : Yongbing Xu
language : en
Publisher: Springer
Release Date : 2015-10-14
Handbook Of Spintronics written by Yongbing Xu and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-10-14 with Science categories.
Over two volumes and 1500 pages, the Handbook of Spintronics will cover all aspects of spintronics science and technology, including fundamental physics, materials properties and processing, established and emerging device technology and applications. Comprising 60 chapters from a large international team of leading researchers across academia and industry, the Handbook provides readers with an up-to-date and comprehensive review of this dynamic field of research. The opening chapters focus on the fundamental physical principles of spintronics in metals and semiconductors, including an introduction to spin quantum computing. Materials systems are then considered, with sections on metallic thin films and multilayers, magnetic tunnelling structures, hybrids, magnetic semiconductors and molecular spintronic materials. A separate section reviews the various characterisation methods appropriate to spintronics materials, including STM, spin-polarised photoemission, x-ray diffraction techniques and spin-polarised SEM. The third part of the Handbook contains chapters on the state of the art in device technology and applications, including spin valves, GMR and MTJ devices, MRAM technology, spin transistors and spin logic devices, spin torque devices, spin pumping and spin dynamics and other topics such as spin caloritronics. Each chapter considers the challenges faced by researchers in that area and contains some indications of the direction that future work in the field is likely to take. This reference work will be an essential and long-standing resource for the spintronics community.
Physics Of And Science With X Ray Free Electron Lasers
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Author : J. Hastings
language : en
Publisher: IOS Press
Release Date : 2020-12-18
Physics Of And Science With X Ray Free Electron Lasers written by J. Hastings and has been published by IOS Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-12-18 with Science categories.
Many X-Ray Free-Electron Lasers (X-FELs) have been designed, built and commissioned since the first lasing of the Linac Coherent Light Source in the hard and soft X-ray regions, and great progress has been made in improving their performance and extending their capabilities. Meanwhile, experimental techniques to exploit the unique properties of X-FELs to explore atomic and molecular systems of interest to physics, chemistry, biology and the material sciences have also been developed. As a result, our knowledge of atomic and molecular science has been greatly extended. Nevertheless, there is still much to be accomplished, and the potential for discovery with X-FELs is still largely unexplored. The next generation of scientists will need to be well versed in both particle beams/FEL physics and X-ray photon science. This book presents material from the Enrico Fermi summer school: Physics of and Science with X-Ray Free-Electron Lasers, held at the Enrico Fermi International School of Physics in Varenna, Italy, from 26 June - 1 July 2017. The lectures presented at the school were aimed at introducing graduate students and young scientists to this fast growing and exciting scientific area, and subjects covered include basic accelerator and FEL physics, as well as an introduction to the main research topics in X-FEL-based biology, atomic molecular optical science, material sciences, high-energy density physics and chemistry. Bridging the gap between accelerator/FEL physicists and scientists from other disciplines, the book will be of interest to all those working in the field.
Physics Briefs
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Author :
language : en
Publisher:
Release Date : 1993
Physics Briefs written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Physics categories.