Excitonic And Vibrational Dynamics In Nanotechnology

The book investigates QDs and SWCNTs using quantum-chemical calculations that describe intricate details of excited-state phenomena and provides information about the mechanisms that occur on the atomic level and that are extremely difficult, if not impossible, to probe experimentally. It delivers, consistently and coherently, a novel approach to nanomaterials which is promising for today's technologies as well as their future. This approach elegantly overcomes computational difficulties known in the field and shares ways to reach top performance in the description of combined quantum effects of molecular vibrations and exciton formation on realistic-size numerical models. The reader will acquire an understanding of the pioneering methodolo

Excitonic and Vibrational Dynamics in Nanotechnology By Svetlana Kilina

From artificial surfaces to living cells, Molecular Nano Dynamics, Vol. I and Vol. II explores more than 40 important methods for dynamic observation of the nanoscale. Edited by absolute science greats from Japan, this two-volume set covers all important aspects of this topic: nanoscale spectroscopy and characterization tools, nanostructure dynamics, single living cell dynamics, active surfaces, and single crystals. Destined to be the definitive reference work on nanoscale molecular dynamics and their observation for years to come, this is a must-have reference for chemists, physicists, physical chemists, theoretical chemists, and materials scientists.

This is the first book to specifically focus on semiconductor nanocrystals, and address their synthesis and assembly, optical properties and spectroscopy, and potential areas of nanocrystal-based devices. The enormous potential of nanoscience to impact on industrial output is now clear. Over the next two decades, much of the science will transfer into new products and processes. One emerging area where this challenge will be very successfully met is the field of semiconductor nanocrystals. Also known as colloidal quantum dots, their unique properties have attracted much attention in the last twenty years.

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.

From the Introduction: Nanotechnology and its underpinning sciences are progressing with unprecedented rapidity. With technical advances in a variety of nanoscale fabrication and manipulation technologies, the whole topical area is maturing into a vibrant field that is generating new scientific research and a burgeoning range of commercial applications, with an annual market already at the trillion dollar threshold. The means of fabricating and controlling matter on the nanoscale afford striking and unprecedented opportunities to exploit a variety of exotic phenomena such as quantum, nanophotonic and nanoelectromechanical effects. Moreover, researchers are elucidating new perspectives on the electronic and optical properties of matter because of the way that nanoscale materials bridge the disparate theories describing molecules and bulk matter. Surface phenomena also gain a greatly increased significance; even the well-known link between chemical reactivity and surface-to-volume ratio becomes a major determinant of physical properties, when it operates over nanoscale dimensions. Against this background, this comprehensive work is designed to address the need for a dynamic, authoritative and readily accessible source of information, capturing the full breadth of the subject. Its six volumes, covering a broad spectrum of disciplines including material sciences, chemistry, physics and life sciences, have been written and edited by an outstanding team of international experts. Addressing an extensive, cross-disciplinary audience, each chapter aims to cover key developments in a scholarly, readable and critical style, providing an indispensible first point of entry to the literature for scientists and technologists from interdisciplinary fields. The work focuses on the major classes of nanomaterials in terms of their synthesis, structure and applications, reviewing nanomaterials and their respective technologies in well-structured and comprehensive articles with extensive cross-references. It has been a constant surprise and delight to have found, amongst the rapidly escalating number who work in nanoscience and technology, so many highly esteemed authors willing to contribute. Sharing our anticipation of a major addition to the literature, they have also captured the excitement of the field itself in each carefully crafted chapter. Along with our painstaking and meticulous volume editors, full credit for the success of this enterprise must go to these individuals, together with our thanks for (largely) adhering to the given deadlines. Lastly, we record our sincere thanks and appreciation for the skills and professionalism of the numerous Elsevier staff who have been involved in this project, notably Fiona Geraghty, Megan Palmer and Greg Harris, and especially Donna De Weerd-Wilson who has steered it through from its inception. We have greatly enjoyed working with them all, as we have with each other.

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.

The subject of semiconductor physics today includes not only many of the aspects that constitute solid state physics, but also much more. It includes what happens at the nanoscale and at surfaces and interfaces, behavior with few interaction events and few carriers —- electrons and their quasi-particle holes —- in the valence bands, the exchange of energies in various forms, the coupling of energetic events over short and long length scales, quantum reversibility tied to macroscale linearity and eventually to nonlinearities, the thermodynamic and statistical consequences of fluctuation-dissipation, and others. This text brings together traditional solid-state approaches from the 20th century with developments of the early part of the 21st century, to reach an understanding of semiconductor physics in its multifaceted forms. It reveals how an understanding of what happens within the material can lead to insights into what happens in its use. The collection of four textbooks in the Electroscience series culminates in a comprehensive understanding of nanoscale devices — electronic, magnetic, mechanical and optical — in the 4th volume. The series builds up to this last subject with volumes devoted to underlying semiconductor and solid-state physics.

This open access book provides a unique and state-of-the-art view on DNA nanotechnology with an eye toward future developments. Intended as a tribute to Nadrian C. Seeman, who founded the field of DNA nanotechnology, the content is an exciting mixture of technical and non-technical material, reviews, tutorials, perspectives, new findings, and open questions. The book aims to inspire current researchers to sit back and think about the big picture, while also enticing new researchers to enter the field. Most of all, the book captures voices from a unique moment in time: 40 years after the publication of the first paper that envisioned DNA nanotechnology. From this vantage point, what are the untold stories, the unspoken concerns, the underlying fundamental issues, the overlooked opportunities, and the unifying grand challenges? What will help us see more clearly, see more creatively, or see farther? What is transpiring right now that could pave the way for the future? To address these questions, leading researchers have contributed 22 chapters, grouped into five sections: perspectives, chemistry and physics, structures, biochemical circuits, and spatial systems. This book will be an important reference point in the field of DNA nanotechnology, both for established researchers looking to take stock of the field and its future, and for newcomers such as graduate students and researchers in other fields who are beginning to appreciate the power and applicability of its methods.