Oscillator strength is a dimensionless quantity used in spectroscopy to quantify the probability of absorption or emission of electromagnetic radiation by an atom or molecule during a transition between energy levels. It is particularly important in the study of electronic transitions in atoms and molecules.

An optode is a device used to measure chemical parameters, primarily dissolved oxygen and other analytes in various environments, including water bodies and biological systems. It combines optical technologies with a sensing element that responds to specific chemical reactions. Optodes typically consist of: 1. **Sensing Layer:** This layer contains fluorescent dyes that change their properties in response to the presence of specific analytes.

Optically Detected Magnetic Resonance (ODMR) is a diagnostic technique used primarily in materials science and quantum computing to investigate the properties of materials at the atomic or molecular level, particularly those containing paramagnetic centers (atoms or ions with unpaired electrons). The method combines optical techniques with magnetic resonance to obtain information about the electronic and structural properties of these materials.

Operando spectroscopy refers to a set of analytical techniques that allow for the study of materials and chemical processes in real-time under their actual operating conditions. This approach is particularly valuable in fields like catalysis, battery research, and material science, where understanding the behavior of a system during its operation is crucial for optimizing performance and developing better materials.

The Nicolson–Ross–Weir (NRW) method is a numerical technique used primarily in computational fluid dynamics and heat transfer to solve the unsteady-state heat conduction equations, particularly within a finite difference framework. It is a finite difference method that is particularly suited for solving parabolic partial differential equations. **Key Features of the Nicolson–Ross–Weir Method:** 1.

Neutron spectroscopy is a technique used in condensed matter physics and materials science to study the dynamics and structure of materials at the atomic and molecular levels. It utilizes neutrons, which are neutral particles found in atomic nuclei, to probe the properties of various materials.

The Nephelauxetic effect refers to the phenomenon where the presence of certain ligands in coordination complexes reduces the bond strength and the energy separation between the d-orbitals of a metal ion. This effect is commonly observed in transition metal complexes. Specifically, when a metal ion is coordinated to ligands, the electrostatic repulsion between the electron clouds of the ligands and the d-electrons of the metal is lessened.

Spectral bands refer to specific ranges of wavelengths within the electromagnetic spectrum where light or other forms of electromagnetic radiation can be analyzed or measured. These bands are utilized in various fields, including remote sensing, telecommunications, astronomy, and more.

Multivariate optical computing (MOC) is an advanced computing paradigm that uses optical systems to perform computations, leveraging the unique properties of light. It involves the simultaneous processing of multiple variables or data dimensions, making it particularly well-suited for tasks that require handling complex, multidimensional data sets. ### Key Features of Multivariate Optical Computing: 1. **Optical Processing**: MOC uses light (usually lasers) to manipulate data.

Multipass spectroscopic absorption cells, also known as multipass cells or multipass absorbers, are optical devices used in spectroscopy to enhance the measurement of absorbance by increasing the path length of light passing through a sample medium. This is particularly useful in applications where the concentration of the absorbing species is very low, making detection challenging.

Multiangle light scattering (MALS) is a technique used to characterize the size, shape, and molecular weight of macromolecules in solution, such as proteins, polymers, and nanoparticles. This method is based on the scattering of light at multiple angles as it interacts with particles suspended in a liquid.

Shape resonance is a phenomenon that occurs in quantum mechanics, particularly in the study of scattering processes. It refers to a temporary trapping of wave function density in a potential well created by the shape of a potential barrier. When particles (such as electrons or nuclei) interact with this potential, certain conditions can lead to an increased likelihood of scattering at specific energies. In a more detailed context, shape resonance happens when the incoming quantum particle has an energy that allows it to temporarily occupy a quasi-bound state.

Molecular vibration refers to the oscillatory motion of atoms within a molecule around their equilibrium positions. This phenomenon occurs because molecular bonds can be thought of as springs that can stretch and compress, allowing the atoms to move closer together or further apart. During vibration, different types of motions can occur, including: 1. **Stretching**: This can be further divided into: - **Symmetric stretching**: Both bonds are elongated or shortened simultaneously.

Molecular term symbols are a notation used in molecular spectroscopy and quantum chemistry to describe the electronic states of molecules. These symbols provide important information about the energy levels and symmetries of molecular states which are pivotal in understanding electronic transitions, bonding characteristics, and other physical properties of molecules. A molecular term symbol generally follows the notation of: \[ ^{2S+1}L_J \] where: - **S** is the total spin angular momentum quantum number.

Molecular electronic transition refers to a process in which a molecule absorbs or emits energy, resulting in a change in its electronic energy state. This typically occurs when electrons in certain molecular orbitals move from a lower energy state (such as a ground state) to a higher energy state (an excited state) or vice versa. These transitions are fundamental to understanding various phenomena in chemistry and physics, including spectroscopy, photochemistry, and the behavior of materials when exposed to light.

"Discoveries" by Guillaume Le Gentil is a comprehensive work that is often associated with his role as an astronomer and explorer in the 18th century. Le Gentil is best known for his observations of the transit of Venus, which he attempted to record from various locations around the world. His work contributed to improvements in the understanding of the solar system, particularly in determining the distance between the Earth and the Sun.

Multi-parametric surface plasmon resonance (MP-SPR) is an advanced technique used to study biomolecular interactions and physical properties at interfaces with high sensitivity and specificity. It is an extension of traditional surface plasmon resonance (SPR) technology, which measures changes in refractive index near metal surfaces caused by biomolecular binding events.

Motional narrowing is a phenomenon observed in nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy. It refers to the reduction in the linewidth of spectral peaks when the motion of the molecules or particles under investigation occurs at a rate that is fast compared to the interaction timescale associated with the magnetic environment.

Micro-spectrophotometry is an analytical technique used to measure the absorbance, transmittance, or reflectance of very small samples, often at the microscopic scale. This method utilizes the principles of UV-Vis (ultraviolet-visible) spectroscopy, allowing scientists to study the optical properties of materials or biological samples with minimal sample consumption.

Belevitch's theorem is a result in the field of control theory and systems engineering, particularly related to the study of linear time-invariant (LTI) systems. The theorem provides a characterization of linear systems in terms of their input-output behavior, specifically concerning the transfer function representation of these systems.