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Nitrogen-15 nuclear magnetic resonance spectroscopy (nitrogen-15 NMR spectroscopy, or just simply 15 N NMR) is a version of nuclear magnetic resonance spectroscopy that examines samples containing the 15 N nucleus. [1] [2] 15 N NMR differs in several ways from the more common 13 C and 1 H NMR.
A portion of this database is still available in a three volume print version from Aldrich. The full electronic version includes a supplement of spectra not included in the paper version. In all, this database includes more than 15,000 compounds with the associated 300 MHz 1 H and 75 MHz 13 C spectra. The product includes the software necessary ...
In traditional MRI RF excitation, an RF pulse, B 1, is applied with a frequency that is resonant with the Larmor precession frequency of the spins of interest. In the frame rotating at the Larmor frequency, the effective field experienced by the spins is in the transverse plane.
An MRI pulse sequence in magnetic resonance imaging (MRI) is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance. [1] A multiparametric MRI is a combination of two or more sequences, and/or including other specialized MRI configurations such as spectroscopy. [2] [3]
Two-Dimensional Nuclear Magnetic Resonance (2D NMR) is an advanced spectroscopic technique that builds upon the capabilities of one-dimensional (1D) NMR by incorporating an additional frequency dimension. This extension allows for a more comprehensive analysis of molecular structures. [1]
The Rabi frequency is a semiclassical concept since it treats the atom as an object with quantized energy levels and the electromagnetic field as a continuous wave. In the context of a nuclear magnetic resonance experiment, the Rabi frequency is the nutation frequency of a sample's net nuclear magnetization vector about a radio-frequency field.
Chemical shift δ is usually expressed in parts per million (ppm) by frequency, because it is calculated from [5] =, where ν sample is the absolute resonance frequency of the sample, and ν ref is the absolute resonance frequency of a standard reference compound, measured in the same applied magnetic field B 0.
The first generation of NMR spectrometers used large Electromagnets weighing hundreds of kilograms or more. Slightly smaller permanent magnet systems were developed in the 1960s-70s at proton resonance frequencies of 60 and 90 MHz and were widely used for chemical analysis using continuous wave methods, but these permanent magnets still weighed hundreds of kilograms and could not be placed on ...