Magic angle spinningIn solid-state NMR spectroscopy, magic-angle spinning (MAS) is a technique routinely used to produce better resolution NMR spectra. MAS NMR consists in spinning the sample (usually at a frequency of 1 to 130 kHz) at the magic angle θm (ca. 54.74°, where cos2θm=1/3) with respect to the direction of the magnetic field. Three main interactions responsible in solid state NMR (dipolar, chemical shift anisotropy, quadrupolar) often lead to very broad and featureless NMR lines.
Chemical shiftIn nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is the resonant frequency of an atomic nucleus relative to a standard in a magnetic field. Often the position and number of chemical shifts are diagnostic of the structure of a molecule. Chemical shifts are also used to describe signals in other forms of spectroscopy such as photoemission spectroscopy.
Gyromagnetic ratioIn physics, the gyromagnetic ratio (also sometimes known as the magnetogyric ratio in other disciplines) of a particle or system is the ratio of its magnetic moment to its angular momentum, and it is often denoted by the symbol γ, gamma. Its SI unit is the reciprocal second per tesla (s⋅T) or, equivalently, the coulomb per kilogram (C⋅kg).
Magnetic fieldIn magnetism and electromagnetism, magnetic field is a physical property of space that quantifies the magnetic influence at a given location. Magnetic fields deflect moving electric charges (including electric currents) apply torques on magnets to twist them in the direction of the magnetic field attract or repel magnets and magnetic material such as iron induce electric currents in electrically conducting material.
J-couplingIn nuclear chemistry and nuclear physics, J-couplings (also called spin-spin coupling or indirect dipole–dipole coupling) are mediated through chemical bonds connecting two spins. It is an indirect interaction between two nuclear spins that arises from hyperfine interactions between the nuclei and local electrons. In NMR spectroscopy, J-coupling contains information about relative bond distances and angles.
AnisotropyAnisotropy () is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical or mechanical properties when measured along different axes, e.g. absorbance, refractive index, conductivity, and tensile strength.
SpectroscopyStudy involving matter and electromagnetic radiationA prism separates white light by dispersing it into its component colors, which can then be studied using spectroscopy.Spectroscopy is the field of study that measures and interprets electromagnetic spectra as it interacts with matter. In narrower contexts, spectroscopy is the precise study of color as generalized from radiated visible light to all bands of the electromagnetic spectrum.Magnetic dipole–dipole interactionMagnetic dipole–dipole interaction, also called dipolar coupling or dipolar interaction, refers to the direct interaction between two magnetic dipoles. Roughly speaking, the magnetic field of a dipole goes as the inverse cube of the distance, and the force of its magnetic field on another dipole goes as the first derivative of the magnetic field. It follows that the dipole-dipole interaction goes as the inverse fourth power of the distance.QuadrupoleA quadrupole or quadrapole is one of a sequence of configurations of things like electric charge or current, magnetic fields, or gravitational mass that can exist in their ideal forms but are usually just part of a multipole expansion of a more complex structure reflecting various orders of complexity.
BiologyBiology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, origin, evolution, and distribution of life.
MedicineDiagnosis, treatment, and prevention of illnessThe Doctor by Sir Luke Fildes (1891)Medicine is the science and practice of caring for patients, managing the diagnosis, prognosis, prevention, treatment and palliation of their injury or disease, while promoting their health. Medicine encompasses a variety of health care practices which evolved to maintain and restore health through the prevention and treatment of illness and infection.*As an Amazon Associate I earn from qualifying purchases.