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Topic Review
UV-Vis Absorption Spectroelectrochemistry
Ultraviolet-visible (UV-Vis) absorption spectroelectrochemistry (SEC) is a multiresponse technique that analyzes the evolution of the absorption spectra in UV-Vis regions during an electrode process. This technique provides information from an electrochemical and spectroscopic point of view. In this way, it enables a better perception about the chemical system of interest. On one hand, molecular information related to the electronic levels of the molecules is obtained from the evolution of the spectra. On the other hand, kinetic and thermodynamic information of the processes is obtained from the electrochemical signal. UV-Vis absorption SEC allows qualitative analysis, through the characterization of the different present compounds, and quantitative analysis, by determining the concentration of the analytes of interest. Furthermore, it helps to determine different electrochemical parameters such as absorptivity coefficients, standard potentials, diffusion coefficients, electronic transfer rate constants, etc. Throughout history, reversible processes have been studied with colored reagents or electrolysis products. Nowadays, it is possible to study all kinds of electrochemical processes in the entire UV-Vis spectral range, even in the near infrared (NIR).
  • 1.3K
  • 31 Oct 2022
Topic Review
Metastable Inner-Shell Molecular State
Metastable Innershell Molecular State (MIMS) is a class of ultra-high-energy short-lived molecules have the binding energy up to 1,000 times larger and bond length up to 100 times smaller than typical molecules. MIMS is formed by inner-shell electrons that are normally resistant to molecular formation. However, in stellar conditions, the inner-shell electrons become reactive to form molecular structures (MIMS) from combinations of all elements in the periodic table. MIMS upon dissociation can emit x-ray photons with energies up to 100 keV at extremely high conversion efficiencies from compression energy to photon energy. MIMS is predicted to exist and dominate radiation processes in extreme astrophysical environments, such as large planet cores, star interiors, and black hole and neutron star surroundings. There, MIMS is predicted to enable highly energy-efficient transformation of the stellar compression energy into the radiation energy. The right schematic illustration shows the proposed four stages of the K-shell MIMS (K-MIMS) formation and x-ray generation process. Stage I: Individual atoms are subjected to the stellar compression and ready for absorbing the compression energy. Stage II: The outer electron shells fuse together under increasing "stellar" pressure. Stage III: At the peak pressure, via pressure ionization K-shell orbits form the K-MIMS, which is vibrationally hot and encapsulated by a Rydberg-like pseudo-L-Shell structure. Stage IV: The K-MIMS cools down by ionizing ("boiling-off") a number of pseudo-L-shell electrons and subsequent optical decay by emitting an x-ray photon. The dissociated atoms return their original atoms states and are ready for absorbing the compression energy. MIMS also can be readily produced in laboratory and industrial environments, such as hypervelocity particle impact, laser fusion and z-machine. MIMS can be exploited for highly energy-efficient production of high intensity x-ray beams for a wide range of innovative applications, such as photolithography, x-ray lasers, and inertial fusion.
  • 1.3K
  • 18 Oct 2022
Topic Review
Shock Capturing Method
In computational fluid dynamics, shock-capturing methods are a class of techniques for computing inviscid flows with shock waves. The computation of flow containing shock waves is an extremely difficult task because such flows result in sharp, discontinuous changes in flow variables such as pressure, temperature, density, and velocity across the shock.
  • 1.2K
  • 25 Nov 2022
Biography
Neil Gershenfeld
Neil A. Gershenfeld (born 1959 or 1960)[1] is an United States professor at MIT and the director of MIT's Center for Bits and Atoms, a sister lab to the MIT Media Lab. His research studies are predominantly focused in interdisciplinary studies involving physics and computer science, in such fields as quantum computing, nanotechnology, and personal fabrication. Gershenfeld attended Swarthmore Col
  • 1.2K
  • 30 Nov 2022
Topic Review
Physical Aspects of Organogelation
The physics side of organogelation is broached through three main aspects, thermodynamics (formation and melting), structure (morphology and molecular organization), and rheology.  Organogelation is a system constituted of fibril-like entities. Gel formation occurs through first-order transitions, chiefly by homogeneous nucleation. 
  • 1.2K
  • 31 Aug 2021
Topic Review
Vibrational Spectroscopy of Linear Molecules
To determine the vibrational spectroscopy of linear molecules, the rotation and vibration of linear molecules are taken into account to predict which vibrational (normal) modes are active in the infrared spectrum and the Raman spectrum.
  • 1.2K
  • 11 Nov 2022
Topic Review
Cell-to-Cell Communication and Information Transfer
Crucial events are generated by criticality, namely by the processes of phase transition from disorder to correlated disorder, affecting key organismal network functions. There is, as suggested by, “a subtle connection between informational exchange within and between networks and the complexity (non-simplicity) of those networks”. West and Grigolini replaced the term complexity with non-simplicity and explain their reasoning by stating that in physics it is easier to understand how phenomena function by the properties or characteristics that are missing, rather than those that are present.
  • 1.2K
  • 22 Sep 2021
Topic Review
Virgo Interferometer
The Virgo interferometer is a large interferometer designed to detect gravitational waves predicted by the general theory of relativity. Virgo is a Michelson interferometer that is isolated from external disturbances: its mirrors and instrumentation are suspended and its laser beam operates in a vacuum. The instrument's two arms are three kilometres long and located near Pisa, Italy. Virgo is part of a scientific collaboration of laboratories from six countries: Italy and France (the two countries behind the project), the Netherlands, Poland, Hungary and Spain. Other interferometers similar to Virgo have the same goal of detecting gravitational waves, including the two LIGO interferometers in the United States (at the Hanford Site and in Livingston, Louisiana). Since 2007, Virgo and LIGO have agreed to share and jointly analyze the data recorded by their detectors and to jointly publish their results. Because the interferometric detectors are not directional (they survey the whole sky) and they are looking for signals which are weak, infrequent, one-time events, simultaneous detection of a gravitational wave in multiple instruments is necessary to confirm the signal validity and to deduce the angular direction of its source. The interferometer is named for the Virgo Cluster of about 1,500 galaxies in the Virgo constellation, about 50 million light-years from Earth. As no terrestrial source of gravitational wave is powerful enough to produce a detectable signal, Virgo must observe the Universe. The more sensitive the detector, the further it can see gravitational waves, which then increases the number of potential sources. This is relevant as the violent phenomena Virgo is potentially sensitive to (coalescence of a compact binary system, neutron stars or black holes; supernova explosion; etc.) are rare: the more galaxies Virgo is surveying, the larger the probability of a detection.
  • 1.2K
  • 18 Nov 2022
Biography
Gino Claudio Segrè
Gino Claudio Segrè (born October 4, 1938) is a Professor of Physics, Emeritus, at the University of Pennsylvania. He is the author of several books on the history of science, particularly on atomic physics. Segrè’s Faust in Copenhagen was a finalist in the Los Angeles Times Book Fair[1] and winner of the American Institute of Physics Science Writing Award.[2] Gino Segrè was born in Flore
  • 1.2K
  • 30 Nov 2022
Topic Review
X-ray Absorption Near Edge Structure
X-ray absorption near edge structure (XANES), also known as near edge X-ray absorption fine structure (NEXAFS), is a type of absorption spectroscopy that indicates the features in the X-ray absorption spectra (XAS) of condensed matter due to the photoabsorption cross section for electronic transitions from an atomic core level to final states in the energy region of 50–100 eV above the selected atomic core level ionization energy, where the wavelength of the photoelectron is larger than the interatomic distance between the absorbing atom and its first neighbour atoms.
  • 1.1K
  • 18 Oct 2022
Topic Review
Spectroelectrochemistry
Spectroelectrochemistry (SEC) is a set of multi-response analytical techniques in which complementary chemical information (electrochemical and spectroscopic) is obtained in a single experiment. Spectroelectrochemistry provides a whole vision of the phenomena that take place in the electrode process. The first spectroelectrochemical experiment was carried out by Theodore Kuwana, PhD, in 1964. The main objective of spectroelectrochemical experiments is to obtain simultaneous, time-resolved and in-situ electrochemical and spectroscopic information on reactions taking place on the electrode surface. The base of the technique consist in studying the interaction of a beam of electromagnetic radiation with the compounds involved in these reactions. The changes of the optical and electrical signal allow us to understand the evolution of the electrode process. The techniques on which the spectroelectrochemistry is based are: Spectroelectrochemistry provides molecular, thermodynamic and kinetic information of reagents, products and/or intermediates involved in the electron transfer process.
  • 1.1K
  • 11 Nov 2022
Topic Review
Compact Fusion Reactor
The Lockheed Martin Compact Fusion Reactor (CFR) is a proposed nuclear fusion reactor project at Lockheed Martin’s Skunk Works. Its high-beta configuration, which implies that the ratio of plasma pressure to magnetic pressure is greater than or equal to 1 (compared to tokamak designs' 0.05), allows a compact fusion reactor (CFR) design and expedited development. The CFR chief designer and technical team lead, Thomas McGuire studied fusion as a source of space propulsion in response to a NASA desire to improve travel times to Mars.
  • 1.1K
  • 21 Nov 2022
Topic Review
Spectrochemistry
Spectrochemistry is the application of spectroscopy in several fields of chemistry. It includes analysis of spectra in chemical terms, and use of spectra to derive the structure of chemical compounds, and also to qualitatively and quantitively analyze their presence in the sample. It is a method of chemical analysis that relies on the measurement of wavelengths and intensity of electromagnetic radiation.
  • 1.1K
  • 30 Oct 2022
Topic Review
ATOM Program System
The ATOM computer system is designed to study the structure of atoms and the physical processes occurring with their participation. 
  • 1.0K
  • 07 Jun 2022
Topic Review
Surface-Extended X-Ray Absorption Fine Structure
Surface-extended X-ray absorption fine structure (SEXAFS) is the surface-sensitive equivalent of the EXAFS technique. This technique involves the illumination of the sample by high-intensity X-ray beams from a synchrotron and monitoring their photoabsorption by detecting in the intensity of Auger electrons as a function of the incident photon energy. Surface sensitivity is achieved by the interpretation of data depending on the intensity of the Auger electrons (which have an escape depth of ~1–2 nm) instead of looking at the relative absorption of the X-rays as in the parent method, EXAFS. The photon energies are tuned through the characteristic energy for the onset of core level excitation for surface atoms. The core holes thus created can then be filled by nonradiative decay of a higher-lying electron and communication of energy to yet another electron, which can then escape from the surface (Auger emission). The photoabsorption can therefore be monitored by direct detection of these Auger electrons to the total photoelectron yield. The absorption coefficient versus incident photon energy contains oscillations which are due to the interference of the backscattered Auger electrons with the outward propagating waves. The period of this oscillations depends on the type of the backscattering atom and its distance from the central atom. Thus, this technique enables the investigation of interatomic distances for adsorbates and their coordination chemistry. This technique benefits from long range order not being required, which sometimes becomes a limitation in the other conventional techniques like LEED (about 10 nm). This method also largely eliminates the background from the signal. It also benefits because it can probe different species in the sample by just tuning the X-ray photon energy to the absorption edge of that species. Joachim Stöhr played a major role in the initial development of this technique.
  • 977
  • 24 Oct 2022
Topic Review
Quantum-Optical Spectroscopy
Quantum-optical spectroscopy is a quantum-optical generalization of laser spectroscopy where matter is excited and probed with a sequence of laser pulses. Classically, such pulses are defined by their spectral and temporal shape as well as phase and amplitude of the electromagnetic field. Besides these properties of light, the phase-amplitude aspects have intrinsic quantum fluctuations that are of central interest in quantum optics. In ordinary laser spectroscopy, one utilizes only the classical aspects of laser pulses propagating through matter such as atoms or semiconductors. In quantum-optical spectroscopy, one additionally utilizes the quantum-optical fluctuations of light to enhance the spectroscopic capabilities by directly shaping and/or detecting the quantum fluctuations of light. Quantum-optical spectroscopy has applications in controlling and characterizing quantum dynamics of many-body states because one can directly access a large set of many-body states, which is not possible in classical spectroscopy.
  • 955
  • 17 Nov 2022
Topic Review
Terahertz Spectroscopy and Technology
Terahertz spectroscopy detects and controls properties of matter with electromagnetic fields that are in the frequency range between a few hundred gigahertz and several terahertz (abbreviated as THz). In many-body systems, several of the relevant states have an energy difference that matches with the energy of a THz photon. Therefore, THz spectroscopy provides a particularly powerful method in resolving and controlling individual transitions between different many-body states. By doing this, one gains new insights about many-body quantum kinetics and how that can be utilized in developing new technologies that are optimized up to the elementary quantum level. Different electronic excitations within semiconductors are already widely used in lasers, electronic components and computers. At the same time, they constitute an interesting many-body system whose quantum properties can be modified, e.g., via a nanostructure design. Consequently, THz spectroscopy on semiconductors is relevant in revealing both new technological potentials of nanostructures as well as in exploring the fundamental properties of many-body systems in a controlled fashion.
  • 942
  • 25 Oct 2022
Topic Review
Two-Dimensional Nanostructures as Surface-Enhanced Raman Scattering Substrates
Two-dimensional nanostructures (2DNS) attract tremendous interest and have emerged as potential materials for a variety of applications, including biomolecule sensing, due to their high surface-to-volume ratio, tuneable optical and electronic properties. Advancements in the engineering of 2DNS and associated technologies have opened up new opportunities. Surface-enhanced Raman scattering (SERS) is a rapid, highly sensitive, non-destructive analytical technique with exceptional signal amplification potential. Several structurally and chemically engineered 2DNS with added advantages (e.g., π–π* interaction), over plasmonic SERS substrates, have been developed specifically towards biomolecule sensing in a complex matrix, such as biological fluids. 
  • 939
  • 11 Jan 2023
Topic Review
Baltimore–Washington Superconducting Maglev Project
The Baltimore–Washington Superconducting Maglev Project (SCMAGLEV) is a proposed project connecting the United States cities of Baltimore, Maryland, and Washington, D.C., with a 40 mi (64 km) maglev train system between their respective central business districts. It is the first segment of the planned Washington-New York Northeast Maglev project. The maglev proposal is not related to the Baltimore–Washington hyperloop proposed by the Boring Company.
  • 937
  • 18 Oct 2022
Topic Review
Phthalocyanine Single-Molecule Magnets
Single-molecule magnets (SMMs) have attracted much attention due to their potential applications in molecular spintronic devices. Rare earth SMMs are considered to be the most promising for application owing to their large magnetic moment and strong magnetic anisotropy.  Phthalocyanines (Pcs) are large rings with 18π electron conjugation and have a wide range of applications in spintronics. 
  • 837
  • 26 May 2023
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