Table of Contents
What Is NMR Spectrum?
Nuclear magnetic resonance (NMR) is a powerful tool for studying the absorption of radio-frequency radiation by atomic nuclei. In a strong magnetic field, the nuclei and electronic energy of certain elements are magnetic, so the nucleus will undergo energy level splitting. When absorbing external electromagnetic radiation, it will split into two or more quantized energy levels. When electromagnetic radiation of appropriate frequency is absorbed, a transition can occur between the generated magnetically induced energy levels, resulting in a NMR phenomenon. In a magnetic field, a nuclear magnetic molecule or nucleus absorbs the energy of the transition from a low energy state to a high energy state will produce a resonance spectrum, which can be used to determine the number, type and relative position of certain atoms in the molecule. According to the object to be measured, NMR spectrum can be classified into the following: 1H-NMR spectrum, 13C-NMR spectrum, fluorine spectrum, phosphorus spectrum, nitrogen spectrum, etc. 1H-NMR and 13C-NMR spectrum are commonly applied in the study of material structure and performance since organic compounds and polymer materials are mainly composed of hydrocarbons.
Figure 1. DFT analysis of the 125Te NMR Knight shifts in Bi2Te3 nanoplatelets. (Papawassiliou, W.; et al. 2020)
Application of NMR Spectrum
Identification of the structure of organic compounds
Identify groups according to chemical shift, determine the way groups are connected by the number of coupling splitting peaks and coupling constant, determine the proton ratio of each group according to the integral area of the peak of each H atom.
NMR imaging technology of polymer materials
NMR technology has been successfully used to detect defects or damages in materials. Scientists use it to study the pore size distribution in extruded or foamed materials, adhesives, and porous materials. NMR technology can be applied to improve processing conditions and product quality.
Multi-component material analysis
NMR technology can be used to measure the relaxation time of polymer blends, determine their compatibility, and investigate the structural stability and performance of materials.
Study polymerization reaction mechanism, polymer sequence structure, qualitative identification of unknown polymers, mechanical and physical properties analysis, etc.