This book focuses on complex shaped micro- and nanostructures for future biomedical and sensing applications that were investigated by both theory and experiments. The first part of the book explores rotation-translation coupling of artificial microswimmers at low Reynolds numbers. Usually corkscrew shapes, i.e chiral shapes, are considered in such experiments, due to their inspiration from nature. However, the analysis of the relevant symmetries shows that achiral objects can also be propulsive, which is experimentally demonstrated for the first time. In the second part, a new single-particle spectroscopy technique was developed and the role of symmetry in such measurements is carefully examined. Spectra stemming from one individual nanoparticle that is moving freely in bulk solution, away from a surface, and only due to Brownian motion, are presented. On that basis, the rotationally averaged chiroptical spectrum of a single nanoparticle is measured - a novel observable that has not been accessible before.

Symmetry is one of the most general concepts in physics. Symmetry arguments are used to explain and predict observations at all length scales, from elementary particles to cosmology. The generality of symmetry arguments, combined with their simplicity, makes them a powerful tool for both fundamental and applied investigations. In electrodynamics, one of the symmetries is the invariance of the equations under exchange of electric and magnetic quantities. The continuous version of this symmetry is most commonly known as electromagnetic duality symmetry. This concept has been accepted for more than a century, and, throughout this time, has influenced other areas of physics, like high energy physics and gravitation. This Special Issue is devoted to electromagnetic duality symmetry and other vareities of dualities in physics. It contains four Articles, one Review and one Perspective. The context of the contributions ranges from string theory to applied nanophotonics, which, as anticipated, shows that duality symmetries in general and electromagnetic duality symmetry in particular are useful in a wide variety of physics fields, both theoretical and applied. Moreover, a number of the contributions show how the use of symmetry arguments and the quantification of symmetry breaking can successfully guide our theoretical understanding and provide us with guidelines for system design.

This book discusses theoretical and experimental advances in metamaterial structures, which are of fundamental importance to many applications in microwave and optical-wave physics and materials science. Metamaterial structures exhibit time-reversal and space-inversion symmetry breaking due to the effects of magnetism and chirality. The book addresses the characteristic properties of various symmetry breaking processes by studying field-matter interaction with use of conventional electromagnetic waves and novel types of engineered fields: twisted-photon fields, toroidal fields, and magnetoelectric fields. In a system with a combined effect of simultaneous breaking of space and time inversion symmetries, one observes the magnetochiral effect. Another similar phenomenon featuring space-time inversion symmetries is related to use of magnetoelectric materials. Cross-coupling of the electric and magnetic components in these material structures, leading to the appearance of new magnetic modes with an electric excitation channel – electromagnons and skyrmions – has resulted in a wealth of strong optical effects such as directional dichroism, magnetochiral dichroism, and rotatory power of the fields. This book contains multifaceted contributions from international leading experts and covers the essential aspects of symmetry-breaking effects, including theory, modeling and design, proven and potential applications in practical devices, fabrication, characterization and measurement. It is ideally suited as an introduction and basic reference work for researchers and graduate students entering this field.

Thorough and up-to-date, this book presents recent developments in this exciting research field. To begin with, the text covers the fabrication of chiral nanomaterials via various synthesis methods, including electron beam lithography, ion beam etching, chemical synthesis and biological DNA directed assembly. This is followed by the relevant theory and reaction mechanisms, with a discussion of the characterization of chiral nanomaterials according to the optical properties of metal nanoparticles, semiconductor nanocrystals, and nanoclusters. The whole is rounded off by a summary of applications in the field of catalysis, sensors, and biomedicine. With its comprehensive yet concise coverage of the whole spectrum of research, this is invaluable reading for senior researchers and entrants to the field of nanoscience and materials science.

This book collects research and review articles covering some recent trends in nonrelativistic quantum electrodynamics, specifically the interaction of atoms or molecules within the quantum electromagnetic radiation field and the related physical effects. Specific topics covered are: two- and three-body dispersion interactions between atoms and molecules, both in the nonretarded van der Waals and the retarded Casimir–Polder regime; vacuum field fluctuations of the electromagnetic field and their effect in atomic systems; dispersion interactions between uniformly accelerating atoms and relation with the Fulling–Davies–Unruh effect; dynamics of atomic systems under strong electromagnetic fields; symmetries in quantum electrodynamics; and open quantum systems.

The field of nanoscience has undergone tremendous growth in the past decade as the number of applications of nanoparticles and nanostructured materials have proliferated. Metal nanoparticles have attracted particular interest due to their potential for applications in areas as diverse as catalysis, medicine and opto-electronics. The chemical and physical properties of metal nanoparticles can vary smoothly or discontinuously with nanoparticle size, depending on the size regime and the property. In the case of bi- or multimetallic nanoparticles ("nanoalloys"), these properties also depend on the elemental composition and the chemical ordering - how the metals are distributed in the nanoparticles.It is this tunability of behavior that makes metal nanoparticles and nanoalloys so versatile and appealing. This book begins with a tutorial introducing the theoretical ideas and models that have been developed to understand metal nanoparticles. It gives an overview of experimental methods for generating and characterizing metal nanoparticles and nanoalloys and of their properties and applications, providing an introduction to material covered in more depth in subsequent chapters. A major theme of all the chapters is the effect of nanoparticle size, shape and surface chemistry on their properties - especially optical and catalytic properties. A unified discussion of the inter-relations between modelling, synthesis and physical properties of nanoparticles and nanoalloys A discussion of the most promising new catalytic and photocatalytic applications of nanoparticles and the approaches used to achieve these goals A tutorial introduction which provides a basis for understanding the subsequent specialized chapters

This book details chiroptical spectroscopic methods: electronic circular dichroism (ECD), optical rotatory dispersion (ORD), vibrational circular dichroism (VCD), and vibrational Raman optical activity (VROA). For each technique, the text presents experimental methods for measurements and theoretical methods for analyzing the experimental data. It also includes a set of experiments that can be adopted for undergraduate teaching laboratories. Each chapter is written in an easy-to-follow format for novice readers, with necessary theoretical formalism in appendices for advanced readers.

Textbook introducing engineers to quantum mechanics and nanostructures, covering the fundamentals and applications to nanoscale materials and nanodevices.

Group theoretical concepts elucidate fundamental physical phenomena, including excitation spectra of quantum systems and complex geometrical structures such as molecules and crystals. These concepts are extensively covered in numerous textbooks. The aim of the present monograph is to illuminate more subtle aspects featuring group theory for quantum mechanics, that is, the concept of dynamical symmetry. Dynamical symmetry groups complement the conventional groups: their elements induce transitions between states belonging to different representations of the symmetry group of the Hamiltonian. Dynamical symmetry appears as a hidden symmetry in the hydrogen atom and quantum rotator problem, but its main role is manifested in nano and meso systems. Such systems include atomic clusters, large molecules, quantum dots attached to metallic electrodes, etc. They are expected to be the building blocks of future quantum electronic devices and information transmitting algorithms. Elucidation of the electronic properties of such systems is greatly facilitated by applying concepts of dynamical group theory.