Download or read book Structure correlated Optical Properties of Monolayer protected Metal Clusters Studied Through Magneto optical and Time resolved Spectroscopies written by Patrick John Herbert and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Magneto-optical (MO) and femtosecond time-resolved spectroscopies have been employed to study the electronic structure and relaxation dynamics of atomically precise monolayer-protected clusters (MPCs). To begin, magnetic circular dichroism (MCD) spectroscopy was introduced and employed to characterize the excitation spectrum of the Au102(pMBA)44 and Au25(PET)18 clusters. It is demonstrated through variable-temperature variable-field (VTVH ) MCD analysis of the Au102(pMBA)44 cluster that: a) the optical properties of distinct structural motifs within MPCs are individually spectroscopically addressable; and b) MO spectroscopy provides the quantification of necessary electronic structure parameters to sufficiently characterize these systems. Electronic structure parameters determined through VTVH analysis, of note, are Land g-factors, fine structure splitting energies, and Faraday Term contributions to the optical magnetic response. From VTVH -MCD study of the Au102(pMBA)44 cluster, the long-contended mechanism for previously observed low temperature magnetism in nanoscale gold was addressed.Having demonstrated the usefulness of VTVH -MCD spectroscopy, the emission analogue, magnetic circular photoluminescence (MCPL) spectroscopy was developed. It was shown through study of the Au25(PET)18 cluster that VTVH -MCPL retains the fundamental formalism and information content of VTVH -MCD. The application of these electronic structure parameters to transient dynamics were utilized in determining the state-resolved mechanism for Au25(PET)18 PL. From this PL mechanism, state-resolved carrier relaxation pathways correlated to superatom-based emission and metal-to-ligand charge transfer emission were characterized. Incorporated into the PL mechanism for Au25(PET)18 were spectroscopic term symbols and fine structure splittings as quantified through VTVH -MCPL analysis. A relation between superatom-based emission to plasmon-mediated emission in larger Au systems was proposed. Next, the influence of structural modification of the Au25(PET)18 cluster on the emission-related carrier dynamics was studied through VTVH -MCPL and VT-PL spectroscopy. To begin, the effect of metal doping to the Au25(PET)18 icosahedral core was studied through analysis of the PdAu24(PET)18 cluster. The PdAu24(PET)18 cluster exhibited significantly lower superatom-based emission intensity, and resulting global PL yield, relative to the Au25(PET)18 cluster. Land g-factor determination and electronic-vibrational coupling analyses suggests that the observation of low emission yield was related to strong coupling to nonradiative channels due to emission from high angular momenta states. The increase in angular momenta was related to spin-orbit coupling interactions between the Pd dopant and surrounding Au icosahedron. Next, the carrier dynamics of the Au25(PET)18 cluster were compared to different sized clusters, namely Au20(PET)15 and Au38(SC12H25)24. Cluster-specific, temperature-dependent PL intensity behaviors were related to size-dependent fine structure energies. In particular, the observation of increased PL intensity for the Au20(PET)15 was related to fine structure resonant, vibrationally mediated energy transfer. The final portion of this thesis focuses on understanding electronic coupling dynamics in MPC dimers. Samples of Au20(PET)15 MPC dimers were formed utilizing a n-ethylene glygol dimethyl ether (n-glyme) molecular bridge. Femtosecond time-resolved transient absorption (fsTA) spectroscopy was utilized to probe the excited-state dynamics for Au20(PET)15-n-glyme-Au20(PET)15 dimers. Effective intercluster separation was controlled using variable length n-glyme, where n = di-, tri-, and tetra-, bridging molecules. A separation-dependent dimer-specific carrier relaxation channel was observed with time constants of 130 20, 60 8, and 36 6 ps for the n = di-, tri- and tetra- dimers, respectively. The increased relaxation time has been attributed to intercluster separation-dependent stabilization of dimer-specific relaxation states. This dimer-specific relaxation channel was further investigated using VTVH -MCPL spectroscopy. VTVH analysis of the dimer PL quantified primarily B-term contributions to the differential response indicating strong coupling between degenerate states. This assignment was in agreement with previous VTVH -MCD studies of polynuclear Au(I)-centered complexes. The results implicated coupling between degenerate Au(I) atoms located in the inorganic semiring units of each cluster as the primary source for emergent dimer carrier dynamics.

Download or read book Annual Review written by Bunshi Kagaku Kenkyūjo and published by . This book was released on 2003 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2566 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical Properties of Size selected Supported Metal Clusters Measured by Cavity Ring down Spectroscopy written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Supported size-selected metal clusters have attracted considerable interest due to their special catalytic properties. Optical spectroscopy is a powerful method to characterise the electronic and geometrical properties of such systems. However, observing the optical properties of these small clusters is not trivial and highly sensitive techniques such as cavity ring-down spectroscopy (CRDS), a method previously used to study gas phase samples, are required. An experimental apparatus capable of studying the optical properties of support size-selected metal clusters is presented here for the first time. The metal clusters were prepared using a state-of-the-art laser ablation source, and size selected prior to deposition onto an optically transparent support material. CRDS was adapted for the study of solid samples over an extended wavelength range and used to investigate the size dependent optical properties of supported metal clusters.

Download or read book Correlations as Causation written by Alexander Anthony Schafgans and published by . This book was released on 2011 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents infrared and magneto-optical spectroscopy experiments that probe emergent phenomena in various correlated and complex electronic materials. By examining the frequency dependent optical constants as a function of temperature, magnetic field, and chemical doping, we draw conclusions about the nature of the physical processes that govern the materials. We predominately explore the vast phase-space of the two currently known families of high-critical temperature superconductors, the cuprates and the pnictides, before turning to a magneto-optical study of Landau levels in a newly discovered three dimensional topological insulator. We present detailed magneto-optical results in the superconducting state of La2-xSrxCuO4 and demonstrate that in-plane magnetic order, present only in the underdoped samples, quenches interplane Josephson coupling. We then generalize these results and show that, for spin ordered cuprates, the universal Josephson relation breaks down. Turning to the 122-family of pnictides, we demonstrate that electronic correlations in BaFe2-xCoxAs2 are doping independent and lead to spectral weight transfer as a function of temperature over an energy scale defined by Hund's rule coupling. By closely monitoring the infrared-active phonon modes across the structural phase transition, we show how Hund's coupling is evident in another observable: the low-temperature phonon oscillator strength enhancement. This previously anomalous phonon behavior results from reduced electronic screening driven by anisotropic in-plane conductivity as a consequence of the Pauli exclusion principle.

Download or read book Magnetic and Magneto Optical Properties and Domain Structure of Co Pd Multilayers written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The domain structure of Co/Pd(1.6/6.3 A)xN multilayers and its relation to the bulk magnetic properties of the samples were studied. The Co/Pd multilayers were deposited by rf and dc magnetron sputtering onto different substrates. It was found that magnetic and magnetooptical properties and domain structure of the multilayers were affected by total film thickness and substrate condition. Magnetization, coercivity, and anisotropy of the films decreased significantly as the film thickness dropped below 100 A. However, Kerr rotation angle had a maximum at the same thickness. The width of the domain structure increased with the decrease of the film thickness attaining the single domain state at N = 10. The initial curves in Co/Pd multilayers were found to depend on demagnetization process. The samples demagnetized by inplane field showed the largest difference between initial curves and the corresponding parts of the loops. Different domain structures were observed in the samples demagnetized by perpendicular and in-plane magnetic fields. Gadetsky, S. and Wu, Teho and Suzuki, T. and Mansuripur, M. Unspecified Center ...

Download or read book Nanocatalysis written by Ulrich Heiz and published by Springer Science & Business Media. This book was released on 2007-01-10 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocatalysis, a subdiscipline of nanoscience, seeks to control chemical reactions by changing the size, dimensionality, chemical composition, and morphology of the reaction center and by changing the kinetics using nanopatterning of the reaction center. This book offers a detailed pedagogical and methodological overview of the field. Readers discover many examples of current research, helping them explore new and emerging applications.

Download or read book Atomically Precise Nanochemistry written by Rongchao Jin and published by John Wiley & Sons. This book was released on 2023-06-12 with total page 533 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explore recent progress and developments in atomically precise nanochemistry Chemists have long been motivated to create atomically precise nanoclusters, not only for addressing some fundamental issues that were not possible to tackle with imprecise nanoparticles, but also to provide new opportunities for applications such as catalysis, optics, and biomedicine. In Atomically Precise Nanochemistry, a team of distinguished researchers delivers a state-of-the-art reference for researchers and industry professionals working in the fields of nanoscience and cluster science, in disciplines ranging from chemistry to physics, biology, materials science, and engineering. A variety of different nanoclusters are covered, including metal nanoclusters, semiconductor nanoclusters, metal-oxo systems, large-sized organometallic nano-architectures, carbon clusters, and supramolecular architectures. The book contains not only experimental contributions, but also theoretical insights into the atomic and electronic structures, as well as the catalytic mechanisms. The authors explore synthesis, structure, geometry, bonding, and applications of each type of nanocluster. Perfect for researchers working in nanoscience, nanotechnology, and materials chemistry, Atomically Precise Nanochemistry will also benefit industry professionals in these sectors seeking a practical and up-to-date resource.

Download or read book Book of Abstracts written by and published by . This book was released on 2000 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical Properties of Size selected Supported Metal Clusters Measured by Cavity Ring down Spectroscopy written by Aras Kartouzian and published by . This book was released on 2010 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Atomically Precise Metal Nanoclusters written by Zhikun Wu and published by Morgan & Claypool Publishers. This book was released on 2020-11-06 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomically precise metal nanocluster research has emerged as a new frontier. This book serves as an introduction to metal nanoclusters protected by ligands. The authors have summarized the synthesis principles and methods, the characterization methods and new physicochemical properties, and some potential applications. By pursuing atomic precision, such nanocluster materials provide unprecedented opportunities for establishing precise relationships between the atomic-level structures and the properties. The book should be accessible to senior undergraduate and graduate students, researchers in various fields (e.g., chemistry, physics, materials, biomedicine, and engineering), R&D scientists, and science policy makers.

Download or read book Physics Briefs written by and published by . This book was released on 1991 with total page 1114 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Visualizing Chemistry written by National Research Council and published by National Academies Press. This book was released on 2006-06-01 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.

Download or read book Journal written by American Chemical Society and published by . This book was released on 2003 with total page 990 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nano written by T. Pradeep and published by McGraw Hill Professional. This book was released on 2008-03-16 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master the Fundamentals of Nanotechnology to Prepare for Nano-Related Career Opportunities If you want to move into the fast-growing field of nanotechnology, you can't afford to miss Nano--The Essentials. This career-building resource offers a rigorous, technological introduction to the fundamentals of nanotechnology, providing everything you need to enter this burgeoning discipline and prepare for nano-related jobs. Packed with over 100 detailed illustrations and lots of practical work-related advice, the book covers the experimental tools of nanotechnology, the basics of nanomaterials, and key applications in fields such as nanosensors, nanobiology, nanomedicine, and nanomachines. This on-target guide takes readers step-by-step through the manipulation of materials in the nanoscale ...fullerenes...carbon nanotubes...self-assembled nanolayers... gas-phase clusters...monolayer-protected metal nanoparticles...core-shell nanoparticles...and much more. Comprehensive and easy-to-understand, Nano--The Essentials features: A solid introduction to the fundamentals of nanomaterials Full details on the experimental tools used in nanotechnology The latest advances in nanobiology and nanomedicine Breakthroughs in the development of nanosensors Cutting-edge innovations in molecular nanomachines Inside this Expert Introduction to the Basics of Nanotechnology • Introduction • Manipulating Materials in the Nanoscale • Fullerenes • Carbon Nanotubes • Self-Assembled Nanolayers • Gas-Phase Clusters • Semiconductor Quantum Dots • Monolayer-Protected Metal Nanoparticles • Core-Shell Nanoparticles • Nanoshells • Nanobiology • Nanosensors • Nanomedicines • Molecular Nanomachines • Nanotribology • Societal Implications

Download or read book Optical Properties of Semiconductor Nanostructures written by Marcin L. Sadowski and published by Springer Science & Business Media. This book was released on 2000-06-30 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical methods for investigating semiconductors and the theoretical description of optical processes have always been an important part of semiconductor physics. Only the emphasis placed on different materials changes with time. Here, a large number of papers are devoted to quantum dots, presenting the theory, spectroscopic investigation and methods of producing such structures. Another major part of the book reflects the growing interest in diluted semiconductors and II-IV nanosystems in general. There are also discussions of the fascinating field of photonic crystals. `Classical' low dimensional systems, such as GsAs/GaAlAs quantum wells and heterostructures, still make up a significant part of the results presented, and they also serve as model systems for new phenomena. New materials are being sought, and new experimental techniques are coming on stream, in particular the combination of different spectroscopic modalities.

Download or read book Supramolecular Gold Chemistry written by Rodolphe Antoine and published by MDPI. This book was released on 2020-06-23 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is about supramolecular gold chemistry. This book provides a unique international forum aimed at covering a broad description of results involving the supramolecular chemistry of gold with a special focus on the gold–sulfur interface leading to hybrid materials ranging from gold–thiolate complexes to thiolate-protected gold nanoclusters and gold–thiolate supramolecular assemblies or nanoparticles. The role of thiolates on the structure and optical features of gold nanohybrid systems (ranging from plasmonic gold nanoparticles and fluorescent gold nanoclusters to self-assembled Au-containing thiolated coordination polymers) is highlighted in the 12 papers presented in this book.