Resolving Structural Changes In Photoinduced Reactions In Solution With X Rays And Electrons

The need for efficient, low-cost solar energy capture has driven interest in mechanistic understanding of light-induced chemical reactions in solution, for instance, natural and artificial photosynthesis. Resolving the structural changes of a molecule during a photoinduced reaction in solution can be challenging, however, with many interdependent intra- and inter-molecular degrees of freedom. This thesis reports experiments using three techniques that can be used to disentangle structural changes during photoinduced reactions: x-ray absorption spectroscopy, valence-to-core x-ray emission spectroscopy, and ultrafast electron diffraction.

This book explores novel computational strategies for simulating excess energy dissipation alongside transient structural changes in photoexcited molecules, and accompanying solvent rearrangements. It also demonstrates in detail the synergy between theoretical modelling and ultrafast experiments in unravelling various aspects of the reaction dynamics of solvated photocatalytic metal complexes. Transition metal complexes play an important role as photocatalysts in solar energy conversion, and the rational design of metal-based photocatalytic systems with improved efficiency hinges on the fundamental understanding of the mechanisms behind light-induced chemical reactions in solution. Theory and atomistic modelling hold the key to uncovering these ultrafast processes. Linking atomistic simulations and modern X-ray scattering experiments with femtosecond time resolution, the book highlights previously unexplored dynamical changes in molecules, and discusses the development of theoretical and computational frameworks capable of interpreting the underlying ultrafast phenomena.

Edited by pioneers in this exciting field, and featuring contributions from leading researchers, this book discusses the principles and applications of XFELs.

The availability of the photosynthetic reaction center's structure at an atomic resolution of less than three angstroms has revolutionized research. This protein is the first integral membrane protein whose structure has been determined with such precision. Each volume of the Photosynthetic Reaction Center contains original research, methods, and reviews. Together, these volumes cover our current understanding of how photosynthesis converts light energy into stored chemical energy. Volume II details the electron transfer process; it is oriented to the physical aspects of photosynthesis. It thus primarily discusses bacterial photosynthesis and model compounds. Volume II features the very complex and rapidly evolving issues associated with the theory of electron transfer in the bacterial reaction center, and explores picosecond and femtosecond spectroscopy. This volume also covers holeburning spectroscopy; primary events of bacterial photosynthesis with emphasis on the application of large, external electric fields designed to manipulate and probe mechanisms of the initial chemistry; the role of accessory carotenoid pigments; the techniques of infrared spectroscopy and magnetic resonance as applied to photosynthesis; and the interplay between natural and artificial photosynthesis.

Lasers and electro-optics is a field of research leading to constant breakthroughs. Indeed, tremendous advances have occurred in optical components and systems since the invention of laser in the late 50s, with applications in almost every imaginable field of science including control, astronomy, medicine, communications, measurements, etc. If we focus on lasers, for example, we find applications in quite different areas. We find lasers, for instance, in industry, emitting power level of several tens of kilowatts for welding and cutting; in medical applications, emitting power levels from few milliwatt to tens of Watt for various types of surgeries; and in optical fibre telecommunication systems, emitting power levels of the order of one milliwatt. This book is divided in four sections. The book presents several physical effects and properties of materials used in lasers and electro-optics in the first chapter and, in the three remaining chapters, applications of lasers and electro-optics in three different areas are presented

This open access book, edited and authored by a team of world-leading researchers, provides a broad overview of advanced photonic methods for nanoscale visualization, as well as describing a range of fascinating in-depth studies. Introductory chapters cover the most relevant physics and basic methods that young researchers need to master in order to work effectively in the field of nanoscale photonic imaging, from physical first principles, to instrumentation, to mathematical foundations of imaging and data analysis. Subsequent chapters demonstrate how these cutting edge methods are applied to a variety of systems, including complex fluids and biomolecular systems, for visualizing their structure and dynamics, in space and on timescales extending over many orders of magnitude down to the femtosecond range. Progress in nanoscale photonic imaging in Göttingen has been the sum total of more than a decade of work by a wide range of scientists and mathematicians across disciplines, working together in a vibrant collaboration of a kind rarely matched. This volume presents the highlights of their research achievements and serves as a record of the unique and remarkable constellation of contributors, as well as looking ahead at the future prospects in this field. It will serve not only as a useful reference for experienced researchers but also as a valuable point of entry for newcomers.

We report the first time-resolved soft x-ray measurements of solvated transition-metal complexes. L-edge spectroscopy directly probes dynamic changes in ligand-field splitting of 3d orbitals associated with the spin transition, and mediated by changes in ligand-bonding. We report the first time-resolved soft x-ray spectroscopy of solution-phase molecular dynamics. Changes in ligand-field splitting and spin-state populations in 3d orbitals of the Fe{sup II} complex are directly probed via transient absorption changes of the Fe L2 and L3 edges following photo-induced metal-to-ligand charge transfer. With the emergence of high-flux ultrafast soft x-ray sources, details on interplay between atomic structure, electronic states, and spin contributions will be revealed. Our experimental approach opens the door to femtosecond soft x-ray investigations of liquid phase chemistry that have previously been inaccessible.

During the last two decades, remarkable and often spectacular progress has been made in the methodological and instrumental aspects of x–ray absorption and emission spectroscopy. This progress includes considerable technological improvements in the design and production of detectors especially with the development and expansion of large-scale synchrotron reactors All this has resulted in improved analytical performance and new applications, as well as in the perspective of a dramatic enhancement in the potential of x–ray based analysis techniques for the near future. This comprehensive two-volume treatise features articles that explain the phenomena and describe examples of X–ray absorption and emission applications in several fields, including chemistry, biochemistry, catalysis, amorphous and liquid systems, synchrotron radiation, and surface phenomena. Contributors explain the underlying theory, how to set up X–ray absorption experiments, and how to analyze the details of the resulting spectra. X-Ray Absorption and X-ray Emission Spectroscopy: Theory and Applications: Combines the theory, instrumentation and applications of x-ray absorption and emission spectroscopies which offer unique diagnostics to study almost any object in the Universe. Is the go-to reference book in the subject for all researchers across multi-disciplines since intense beams from modern sources have revolutionized x-ray science in recent years Is relevant to students, postdocurates and researchers working on x-rays and related synchrotron sources and applications in materials, physics, medicine, environment/geology, and biomedical materials

The behavior of nanoscale materials can change rapidly with time either because the environment changes rapidly or because the influence of the environment propagates quickly across the intrinsically small dimensions of nanoscale materials. Extremely fast time resolution studies using X-rays, electrons and neutrons are of very high interest to many researchers and is a fast-evolving and interesting field for the study of dynamic processes. Therefore, in situ structural characterization and measurements of structure-property relationships covering several decades of length and time scales (from atoms to millimeters and femtoseconds to hours) with high spatial and temporal resolutions are crucially important to understand the synthesis and behavior of multidimensional materials. The techniques described in this book will permit access to the real-time dynamics of materials, surface processes and chemical and biological reactions at various time scales. This book provides an interdisciplinary reference for research using in situ techniques to capture the real-time structural and property responses of materials to surrounding fields using electron, optical and x-ray microscopies (e.g. scanning, transmission and low-energy electron microscopy and scanning probe microscopy) or in the scattering realm with x-ray, neutron and electron diffraction.