Application of NMR techniques in studying the dynamics of some
... Assuming a multi-exponential decay, the NMR signal was Laplace inverted using the well known UPEN algorithm5. The resulted transverse relaxation time distributions can give us complex information related to the polymer chain motions. We have found out that a common effect of all aging factors is to ...
... Assuming a multi-exponential decay, the NMR signal was Laplace inverted using the well known UPEN algorithm5. The resulted transverse relaxation time distributions can give us complex information related to the polymer chain motions. We have found out that a common effect of all aging factors is to ...
Lecture 34: NMR spectroscopy
... Chemical applications: J coupling Just as the electronic environment affects local magnetic environment of a given nucleus, it can also be affected by neighboring nuclei. Recall, each nucleus acts like a tiny magnet. Depending on the orientation of nuclear spin, the magnetic field felt by a given n ...
... Chemical applications: J coupling Just as the electronic environment affects local magnetic environment of a given nucleus, it can also be affected by neighboring nuclei. Recall, each nucleus acts like a tiny magnet. Depending on the orientation of nuclear spin, the magnetic field felt by a given n ...
Nuclear Magnetic Resonance
... detecting nuclear magnetic resonance absorption in bulk matter. – The energy absorption was observed by irradiating the sample with radiofrequency field and varying the strength of the magnetic field (continue wave). – 1952 Nobel prize in physics. ...
... detecting nuclear magnetic resonance absorption in bulk matter. – The energy absorption was observed by irradiating the sample with radiofrequency field and varying the strength of the magnetic field (continue wave). – 1952 Nobel prize in physics. ...
rangus-prezentacija
... Direct dipole coupling Indirect dipole coupling or J-coupling Quadrupolar interaction ...
... Direct dipole coupling Indirect dipole coupling or J-coupling Quadrupolar interaction ...
PhD Position: Dynamic Nuclear Polarization using Electron-Nuclear Double Resonance
... molecules to working human brains. However, many NMR experiments are limited by the small fraction of nuclei which are spin polarized. Electrons are more easily polarized but electron paramagnetic resonance (EPR) is only useful for studying materials with unpaired electron spins. We are developing t ...
... molecules to working human brains. However, many NMR experiments are limited by the small fraction of nuclei which are spin polarized. Electrons are more easily polarized but electron paramagnetic resonance (EPR) is only useful for studying materials with unpaired electron spins. We are developing t ...
Nuclear magnetic resonance
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a magnetic field absorb and re-emit electromagnetic radiation. This energy is at a specific resonance frequency which depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms; in practical applications, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz).NMR allows the observation of specific quantum mechanical magnetic properties of the atomic nucleus. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals, and non-crystalline materials through NMR spectroscopy. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI).All isotopes that contain an odd number of protons and/or of neutrons (see Isotope) have an intrinsic magnetic moment and angular momentum, in other words a nonzero spin, while all nuclides with even numbers of both have a total spin of zero. The most commonly studied nuclei are 1H and 13C, although nuclei from isotopes of many other elements (e.g. 2H, 6Li, 10B, 11B, 14N, 15N, 17O, 19F, 23Na, 29Si, 31P, 35Cl, 113Cd, 129Xe, 195Pt) have been studied by high-field NMR spectroscopy as well.A key feature of NMR is that the resonance frequency of a particular substance is directly proportional to the strength of the applied magnetic field. It is this feature that is exploited in imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance frequencies of the sample's nuclei depend on where in the field they are located. Since the resolution of the imaging technique depends on the magnitude of magnetic field gradient, many efforts are made to develop increased field strength, often using superconductors. The effectiveness of NMR can also be improved using hyperpolarization, and/or using two-dimensional, three-dimensional and higher-dimensional multi-frequency techniques.The principle of NMR usually involves two sequential steps:The alignment (polarization) of the magnetic nuclear spins in an applied, constant magnetic field B0.The perturbation of this alignment of the nuclear spins by employing an electro-magnetic, usually radio frequency (RF) pulse. The required perturbing frequency is dependent upon the static magnetic field (H0) and the nuclei of observation.The two fields are usually chosen to be perpendicular to each other as this maximizes the NMR signal strength. The resulting response by the total magnetization (M) of the nuclear spins is the phenomenon that is exploited in NMR spectroscopy and magnetic resonance imaging. Both use intense applied magnetic fields (H0) in order to achieve dispersion and very high stability to deliver spectral resolution, the details of which are described by chemical shifts, the Zeeman effect, and Knight shifts (in metals).NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), and in several types of magnetometers.