Download or read book Molecular Modeling and Investigation of Ultrafast Dynamics in Nano systems written by Jung Khadga Karki and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this PhD thesis, the results of molecular dynamics simulation studies of structural properties of nano-aggregates and experimental time-resolved spectroscopy studies of exciton dynamics in nano-structures of chromophores are presented. The OPLS force field parameters of chlorophyll a, astaxanthin (a carotenoid) and phenyltrimethoxysilane molecules are developed to study their structural, physical and thermodynamic properties in solution using classical molecular dynamics simulations. Simulations of chlorophyll a in different solvents show formation of monomeric, dimeric and multimeric structures in methanol, benzene and water, respectively. The structures of the aggregates show that different functional groups present in the ring of the molecule, hydrophobicity of the phytol tail and the water molecules coordinated to the Mg of the chlorin ring play important role in aggregation. Simulations of astaxanthin in water and ethanol mixtures show formation of aggregates in the mixtures in which the water content is more than 50\%. The results show that hydrophobicity of the conjugated chain in astaxanthin plays a major role in aggregation. Apart from the natural systems like light-harvesting complexes, chlorophylls and carotenoids also aggregate on surfaces. In light-harvesting complexes, the aggregation is controlled by proteins in such a way that the aggregates efficiently collect sunlight, which the plants use for photosynthesis. Such a controlled aggregation is also necessary to develop nano-antennas of these chromophores for artificial photosynthesis or other photovoltaic systems. One of the ways to control their aggregation in surfaces is to change the hydrophobicity of the surface. For this reason, a molecular model of the phenyltrimethoxysilane has been parameterized to model hydrophobic phenyl-functionalized inorganic surfaces like silica surface. Functioning of nano-assemblies of chromophores for photovoltaic application relies on formation of excitons, their motion, energy dissipation, charge separation, etc. that follow the absorption of photons. The processes like formation of excitons and charge separation are desirable while energy dissipation by vibrational relaxation are undesirable. In order to control aggregation such that the desirable functions are maximized, the different processes occurring in the nano-aggregates need to investigated. These processes, which occur in femto-second to pico-second timescales, can be studied using different techniques of time-resolved spectroscopy. However, the widely used techniques in time-resolved spectroscopy do not have spatial resolution high enough to study dynamics in individual nano-structures or nano-meter or sub-nanometer thin layers of chromophores. The experimental work presented here present the development and implementation of two techniques: near-field pump-probe technique to study the ultra-fast processes in nano-structures with 100 nm spatial resolution, and transient grating technique to study ultra-fast processes in few to sub-nanometer thin films of chromophores. Results of the investigation of exciton dynamics using the two techniques on 3,4,9,10 Perylenetetracarboxylic dianhydride show ultra-fast exciton annihilation and self-trapping of excitons at high exciton densities. The results also show that the pump-probe spectroscopy using the near field technique allows one to quantify the annihilation rate and diffusion constant of the excitons in nano-crystals. These techniques can also be used to investigate ultra-fast processes in the nano-structures of chlorophylls, carotenoids and their derivatives on functionalized surfaces.
Download or read book Molecular Modeling and Investigation of Ultrafast Dynamics in Nano systems written by Jung Khadga Karki and published by . This book was released on 2011 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this PhD thesis, the results of molecular dynamics simulation studies of structural properties of nano-aggregates and experimental time-resolved spectroscopy studies of exciton dynamics in nano-structures of chromophores are presented. The OPLS force field parameters of chlorophyll a, astaxanthin (a carotenoid) and phenyltrimethoxysilane molecules are developed to study their structural, physical and thermodynamic properties in solution using classical molecular dynamics simulations. Simulations of chlorophyll a in different solvents show formation of monomeric, dimeric and multimeric structures in methanol, benzene and water, respectively. The structures of the aggregates show that different functional groups present in the ring of the molecule, hydrophobicity of the phytol tail and the water molecules coordinated to the Mg of the chlorin ring play important role in aggregation. Simulations of astaxanthin in water and ethanol mixtures show formation of aggregates in the mixtures in which the water content is more than 50\%. The results show that hydrophobicity of the conjugated chain in astaxanthin plays a major role in aggregation. Apart from the natural systems like light-harvesting complexes, chlorophylls and carotenoids also aggregate on surfaces. In light-harvesting complexes, the aggregation is controlled by proteins in such a way that the aggregates efficiently collect sunlight, which the plants use for photosynthesis. Such a controlled aggregation is also necessary to develop nano-antennas of these chromophores for artificial photosynthesis or other photovoltaic systems. One of the ways to control their aggregation in surfaces is to change the hydrophobicity of the surface. For this reason, a molecular model of the phenyltrimethoxysilane has been parameterized to model hydrophobic phenyl-functionalized inorganic surfaces like silica surface. Functioning of nano-assemblies of chromophores for photovoltaic application relies on formation of excitons, their motion, energy dissipation, charge separation, etc. that follow the absorption of photons. The processes like formation of excitons and charge separation are desirable while energy dissipation by vibrational relaxation are undesirable. In order to control aggregation such that the desirable functions are maximized, the different processes occurring in the nano-aggregates need to investigated. These processes, which occur in femto-second to pico-second timescales, can be studied using different techniques of time-resolved spectroscopy. However, the widely used techniques in time-resolved spectroscopy do not have spatial resolution high enough to study dynamics in individual nano-structures or nano-meter or sub-nanometer thin layers of chromophores. The experimental work presented here present the development and implementation of two techniques: near-field pump-probe technique to study the ultra-fast processes in nano-structures with 100 nm spatial resolution, and transient grating technique to study ultra-fast processes in few to sub-nanometer thin films of chromophores. Results of the investigation of exciton dynamics using the two techniques on 3,4,9,10 Perylenetetracarboxylic dianhydride show ultra-fast exciton annihilation and self-trapping of excitons at high exciton densities. The results also show that the pump-probe spectroscopy using the near field technique allows one to quantify the annihilation rate and diffusion constant of the excitons in nano-crystals. These techniques can also be used to investigate ultra-fast processes in the nano-structures of chlorophylls, carotenoids and their derivatives on functionalized surfaces.
Download or read book Ultrafast Dynamics at the Nanoscale written by Stefan Haacke and published by CRC Press. This book was released on 2017-01-06 with total page 529 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrafast Dynamics at the Nanoscale provides a combined experimental and theoretical insight into the molecular-level investigation of light-induced quantum processes in biological systems and nanostructured (bio)assemblies. Topics include DNA photostability and repair, photoactive proteins, biological and artificial light-harvesting systems, plasmonic nanostructures, and organic photovoltaic materials, whose common denominator is the key importance of ultrafast quantum effects at the border between the molecular scale and the nanoscale. The functionality and control of these systems have been under intense investigation in recent years in view of developing a detailed understanding of ultrafast nanoscale energy and charge transfer, as well as fostering novel technologies based on sustainable energy resources. Both experiment and theory have made big strides toward meeting the challenge of these truly complex systems. This book, thus, introduces the reader to cutting-edge developments in ultrafast nonlinear optical spectroscopies and the quantum dynamical simulation of the observed dynamics, including direct simulations of two-dimensional optical experiments. Taken together, these techniques attempt to elucidate whether the quantum coherent nature of ultrafast events enhances the efficiency of the relevant processes and where the quantum–classical boundary sets in, in these high-dimensional biological and material systems. The chapters contain well-illustrated accounts of the authors’ research work, including didactic introductory material, and address a multidisciplinary audience from chemistry, physics, biology, and materials sciences. The book is, therefore, a must-have for graduate- and postgraduate-level researchers who wish to learn about molecular nanoscience from a combined spectroscopic and theoretical viewpoint.
Download or read book Ultrafast Dynamics In Molecules Nanostructures And Interfaces Selected Lectures Presented At Symposium On Ultrafast Dynamics Of The 7th International Conference On Materials For Advanced Technologies written by Guglielmo Lanzani and published by World Scientific. This book was released on 2014-01-22 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Primary events in natural systems or devices occur on extremely short time scales, and yet determine in many cases the final performance or output. For this reason research in ultrafast science is of primary importance and impact in both fundamental research as well as its applications. This book reviews the advances in the field, addressing timely and open questions such as the role of quantum coherence in biology, the role of excess energy in electron injection at photovoltaic interfaces or the dynamics in quantum confined structures (e.g. multi carrier generation). The approach is that of a monograph, with a broad tutorial introduction and an overview of the recent results. This volume includes selected lectures presented at Symposium on Ultrafast Dynamics of the 7th International Conference on Materials for Advanced Technologies.
Download or read book Molecular Dynamics written by Daniel E. Garcia and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular dynamics (MD) is a computer simulation of physical movements of atoms and molecules. The atoms and molecules are allowed to interact for a period of time, giving a view of the motion of the atoms. This book presents current research on the theory, kinetics and implementation of molecular dynamics. Topics discussed in this compilation include the molecular dynamics of proteins; molecular dynamics simulations on the extraction of fluid transport properties at the nanoscale; investigation of structural properties of drug-metabolising enzymes using molecular dynamics simulation; double-pulse laser control of ultrafast optical Kerr effect in liquid; ZnO nano-structures for biosensing; and molecular dynamics simulations of liquid and ionic solvation of carbon tetrachloride.
Download or read book Computational Studies Of New Materials Ii From Ultrafast Processes And Nanostructures To Optoelectronics Energy Storage And Nanomedicine written by Thomas F George and published by World Scientific. This book was released on 2011-01-07 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Studies of New Materials was published by World Scientific in 1999 and edited by Daniel Jelski and Thomas F George. Much has happened during the past decade. Advances have been made on the same materials discussed in the 1999 book, including fullerenes, polymers and nonlinear optical processes in materials, which are presented in this 2010 book. In addition, different materials and topics are comprehensively covered, including nanomedicine, hydrogen storage materials, ultrafast laser processes, magnetization and light-emitting diodes.
Download or read book Ultrafast Dynamics at the Nanoscale written by Stefan Haacke and published by CRC Press. This book was released on 2017-01-06 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrafast Dynamics at the Nanoscale provides a combined experimental and theoretical insight into the molecular-level investigation of light-induced quantum processes in biological systems and nanostructured (bio)assemblies. Topics include DNA photostability and repair, photoactive proteins, biological and artificial light-harvesting systems, plasmonic nanostructures, and organic photovoltaic materials, whose common denominator is the key importance of ultrafast quantum effects at the border between the molecular scale and the nanoscale. The functionality and control of these systems have been under intense investigation in recent years in view of developing a detailed understanding of ultrafast nanoscale energy and charge transfer, as well as fostering novel technologies based on sustainable energy resources. Both experiment and theory have made big strides toward meeting the challenge of these truly complex systems. This book, thus, introduces the reader to cutting-edge developments in ultrafast nonlinear optical spectroscopies and the quantum dynamical simulation of the observed dynamics, including direct simulations of two-dimensional optical experiments. Taken together, these techniques attempt to elucidate whether the quantum coherent nature of ultrafast events enhances the efficiency of the relevant processes and where the quantum–classical boundary sets in, in these high-dimensional biological and material systems. The chapters contain well-illustrated accounts of the authors’ research work, including didactic introductory material, and address a multidisciplinary audience from chemistry, physics, biology, and materials sciences. The book is, therefore, a must-have for graduate- and postgraduate-level researchers who wish to learn about molecular nanoscience from a combined spectroscopic and theoretical viewpoint.
Download or read book Nanoscale Coherent Control Ultrafast Dynamics of Single Molecules Individual Light Harvesting Complexes and Discrete Nanoantennas at Room Temperature written by Daan Brinks and published by . This book was released on 2013 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrafast pulses allow observation of molecular dynamics with femtosecond time resolution through pump probe experiments. However, averaging over an ensemble of molecules tends to wash out phase sensitive information, necessary to probe quantum effects, due to the intrinsic inhomogeneity in molecular conformations, orientations and interactions that lead to unique potential energy landscapes for each molecule. It is therefore important to go beyond the ensemble average when looking at quantum dynamics of organic systems at room temperature, and resolve the behaviour of specific molecules on an individual basis. In this thesis, we show the creation, manipulation and observation of ultrafast coherent effects in single molecules at room temperature, and resolve a certain measure of environmental influence on the specific dynamics of each molecule. Moreover, we apply this insight to investigate a functional light harvesting biosystem, and lay the basis for a technique that has the time and space resolution required to observe these systems in vivo. In chapter 1, we introduce the concepts and techniques the research in this thesis is built on. In chapter 2, we treat the possibility of controlling ultrafast pulses at the high-NA diffraction limit, and come to conclusions about the procedure to follow there that hold for all pulse-shaping experiments. We show in proof of principle experiments that we can control the ultrafast characteristics of optical pulses in nanometric excitation volumes. In chapters 3 and 4 we report the creation, detection and control of ultrafast quantum dynamics in single organic molecules at room temperature. We show that manipulation of superposition states is possible in these systems within a coherence dephasing time of ̃50 fs. This leads to the first observation of rabi-oscillations in room temperature single molecules, to ultrafast operation of an organic qubit, and to the creation of non-stationary superposition states (vibrational wavepackets). We probe the influence of the local environment on the composition and dynamics of these wavepackets and show we can optimize the state preparation protocol for each individual molecule in its own nanoenvironment, leading to high fidelity coherent control. In these chapters we lay out the proof of principle work of detecting the quantumdynamics of a complex system in interaction with its environment at room temperature. In chapter 5 we discuss application of these techniques to the investigation of long lived coherence in photosynthetic systems. We show that electronic coherence between different rings of the LH2 system persists to time scales of 100s of femtoseconds at room temperature. Moreover we show that the energy transfer pathways in LH2 adapt to environmentally induced changes in the molecule and that the nature of the transfer remains coherent for each pathway, providing strong evidence that coherent energy transfer is the optimum process for energy transfer in photosynthesis. Finally, in chapter 6 we take the technical development one step further and report on the creation of a framework based on plasmonic antennas that allows for control of the amplitude-phase characteristics in nanometric sized hotspot fields. We show for the first time that the ultrafast characteristics of plasmonic hotspots can directly be engineered through design of the plasmonic system and experimentally demonstrate two much-anticipated examples: a sub-diffraction resolution phase shaper and an ultrafast plasmonic switch for pump probe experiments. The results presented in this thesis form the first creation and observation of ultrafast coherent dynamics in individual molecular systems at room temperature. This is a necessary step to be able to do true quantum tomography in complex systems, resolve the influence of the environment on molecular dynamics, and investigate the physics that determines evolutionary optimization and functionality in biomolecules.
Download or read book Femtochemistry And Femtobiology Ultrafast Dynamics In Molecular Science written by Abderrazzak Douhal and published by World Scientific. This book was released on 2002-05-30 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains important contributions from top international scientists on the-state-of-the-art of femtochemistry and femtobiology at the beginning of the new millennium. It consists of reviews and papers on ultrafast dynamics in molecular science.The coverage of topics highlights several important features of molecular science from the viewpoint of structure (space domain) and dynamics (time domain). First of all, the book presents the latest developments, such as experimental techniques for understanding ultrafast processes in gas, condensed and complex systems, including biological molecules, surfaces and nanostructures. At the same time it stresses the different ways to control the rates and pathways of reactive events in chemistry and biology. Particular emphasis is given to biological processes as an area where femtodynamics is becoming very useful for resolving the structural dynamics from techniques such as electron diffraction, and X-ray and IR spectroscopy. Finally, the latest developments in quantum control (in both theory and experiment) and the experimental pulse-shaping techniques are described.
Download or read book Kinetics and Dynamics written by Piotr Paneth and published by Springer Science & Business Media. This book was released on 2010-08-03 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Kinetics and Dynamics" on molecular modeling of dynamic processes opens with an introductory overview before discussing approaches to reactivity of small systems in the gas phase. Then it examines studies of systems of increasing complexity up to the dynamics of DNA. This title has interdisciplinary character presenting wherever possible an interplay between the theory and the experiment. It provides basic information as well as the details of theory and examples of its application to experimentalists and theoreticians interested in modeling of dynamic processes in chemical and biochemical systems. All contributing authors are renowned experts in their fields and topics covered in this volume represent the forefront of today’s science.
Download or read book Theoretical Investigation on Light driven Ultrafast Dynamics in Nanoscale written by Adrian Domínguez Castro and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this doctoral thesis, the three pillars of theoretical modeling such as interpretation, confirmation and prediction, have underlined the importance of simulations techniques in femtochemistry on the analysis and understanding of experimental data and the vaticination of photoinduced charge transfer. The significance and novelty of the studies presented is that due to the several challenges on the accurate description of the charge transfer processes involving the systems of interest, the benefits of the DFT and DFTB based calculations are highlighted. From the ground state description, the computation of X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) and the excited states studies applying the real-time Ehrenfest approach in the TDDFTB framework. This last method is a valuable tool for the study of large systems for new materials design with applications in photochemistry and nanophotonics. This work could be useful for the investigation on this topic in the near future.
Download or read book Molecular Modeling of Geochemical Reactions written by James D. Kubicki and published by John Wiley & Sons. This book was released on 2016-07-12 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular processes in nature affect human health, the availability of resources and the Earth’s climate. Molecular modelling is a powerful and versatile toolbox that complements experimental data and provides insights where direct observation is not currently possible. Molecular Modeling of Geochemical Reactions: An Introduction applies computational chemistry to geochemical problems. Chapters focus on geochemical applications in aqueous, petroleum, organic, environmental, bio- and isotope geochemistry, covering the fundamental theory, practical guidance on applying techniques, and extensive literature reviews in numerous geochemical sub-disciplines. Topics covered include: • Theory and Methods of Computational Chemistry • Force Field Application and Development • Computational Spectroscopy • Thermodynamics • Structure Determination • Geochemical Kinetics This book will be of interest to graduate students and researchers looking to understand geochemical processes on a molecular level. Novice practitioners of molecular modelling, experienced computational chemists, and experimentalists seeking to understand this field will all find information and knowledge of use in their research.
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.
Download or read book Attosecond Nanophysics written by Peter Hommelhoff and published by John Wiley & Sons. This book was released on 2015-01-30 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first broad and in-depth overview of current research in attosecond nanophysics, covering the field of active plasmonics via attosecond science in metals and dielectrics to novel imaging techniques with the highest spatial and temporal resolution. The authors are pioneers in the field and present here new developments and potential novel applications for ultra-fast data communication and processing, discussing the investigation of the natural timescale of electron dynamics in nanoscale solid state systems. Both an introduction for starting graduate students, as well as a look at the current state of the art in this hot and emerging field.
Download or read book Molecular Dynamics written by Lichang Wang and published by BoD – Books on Demand. This book was released on 2012-04-05 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Dynamics is a two-volume compendium of the ever-growing applications of molecular dynamics simulations to solve a wider range of scientific and engineering challenges. The contents illustrate the rapid progress on molecular dynamics simulations in many fields of science and technology, such as nanotechnology, energy research, and biology, due to the advances of new dynamics theories and the extraordinary power of today's computers. This first book begins with a general description of underlying theories of molecular dynamics simulations and provides extensive coverage of molecular dynamics simulations in nanotechnology and energy. Coverage of this book includes: Recent advances of molecular dynamics theory Formation and evolution of nanoparticles of up to 106 atoms Diffusion and dissociation of gas and liquid molecules on silicon, metal, or metal organic frameworks Conductivity of ionic species in solid oxides Ion solvation in liquid mixtures Nuclear structures
Download or read book Ion and Molecule Transport in Membrane Systems written by Victor Nikonenko and published by MDPI. This book was released on 2021-08-10 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Membranes play an enormous role in our life. Biological cell membranes control the fluxes of substances in and out of cells. Artificial membranes are widely used in numerous applications including “green” separation processes in chemistry, agroindustry, biology, medicine; they are used as well in energy generation from renewable sources. They largely mimic the structure and functions of biological membranes. The similarity in the structure leads to the similarity in the properties and the approaches to study the laws governing the behavior of both biological and artificial membranes. In this book, some physico-chemical and chemico-physical aspects of the structure and behavior of biological and artificial membranes are investigated.
Download or read book Annual Review of Nano Research written by Guozhong Cao and published by World Scientific. This book was released on 2008 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second volume of the Annual Review of Nano Research focuses mainly on nanofabrication, nanomaterials and nanostructures, and energy application of nanomaterials. All of the review chapters are contributed by well-published scientists and bring the most recent advancements in selected topics to the readers. This review volume will perfectly serve dual purposes: either as an excellent introduction to scientists whose expertise lies in different fields but who are interested in learning about nanotechnology, or as a quick reference for experts active in the field of nanotechnology and nanoscience.
