Nuclear magnetic resonance spectroscopy operating frequency

Radio and TV broadcasts use radio frequency radiation. In addition, nuclear magnetic resonance spectroscopy, which causes transitions between nuclear spin states, uses radiation from this region. One typical NMR spectrometer operates at 2 X 108 Hz or 200 MHz (1.9 X 10 5 kcal/mol or 8 X 10 s kJ/mol). NMR spectroscopy is discussed in Chapter 14... 

Nuclear magnetic resonance spectroscopy is a complex technique that is used to determine the constituents of foods. This method makes use of the fact that some compounds contain certain atomic nuclei which can be identified from a nuclear magnetic resonance spectrum, which measures variations in frequency of electromagnetic radiation absorbed. It provides more specific and detailed information of the conformational structure of compoimds than, for example, NIRS but is more costly and requires more time and skUl on the part of the operator. For these reasons, it is more suited to research work and for cases in which the results from simpler spectroscopy techniques require further investigation. Nuclear magnetic resonance spectroscopy has been useful in the investigation of the soluble and structural components of forages. 

The microstructure of PP and propylene-based copolymers were determined via infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. The NMR spectra of 5% copolymer solutions in o-dichlo-robenzene were measured at 120°C on a Bruker DPX-2500 instrument operating at a frequency of 162.895 MHz. 

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