HOW NMR WORKS - Chemical Analysis, Life Sciences, NMR WORKS Nuclear magnetic resonance (NMR) is a...

HOW NMR WORKS - Chemical Analysis, Life Sciences, NMR WORKS Nuclear magnetic resonance (NMR) is a technique used by scientists in a broad range of disciplines—including synthetic
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Transcript of HOW NMR WORKS - Chemical Analysis, Life Sciences, NMR WORKS Nuclear magnetic resonance (NMR) is a...

  • MAGNETIC FIELD

    B1B0

    TRANSMITTER

    RECEIVER

    GRADIENTS

    SHIM POWER SUPPLY

    MAGNETIC FIELD

    B1B0

    MAGNETIC FIELD

    B1B0

    01

    03

    04

    02

    Liquid Nitrogen77 Kelvin

    Liquid Helium4.2 Kelvin

    Superconducting Magnet4.2 Kelvin

    Shim CoilsRoom Temperature

    ProbeRemovable

    Sample

    H NMR SPECTRUM OF ETHANOL (CH3CH2OH)

    5 4 3 2 1 0 (ppm)

    CH2OH

    CH3

    STEP

    STEP

    STEP

    STEP

    Liquid Helium4.2 Kelvin

    Liquid Nitrogen 77 Kelvin

    Superconducting Magnet4.2 Kelvin

    Shim CoilsRoom Temperature

    ProbeRemovable

    COMPUTER

    90 RF

    FID

    HOW NMR WORKS Nuclear magnetic resonance (NMR) is a technique used by scientists in a broad range of disciplinesincluding synthetic chemistry, drug discovery and development, life science research, process monitoring, food quality and safety, petroleum discovery and production, biochemistry, and materials scienceto understand molecular structure and molecular dynamics, quantify molecular species, and monitor chemical processes. Learn more at www.agilent.com/chem/nmr.

    Nuclear spins in a collection of ethanol molecules after a 90 RF pulse.

    Deliver the Radio Frequency (RF) pulses. Under the control of the host computer and VnmrJ software, the sophisticated electronics in the NMR console generate and receive RF pulses. The RF pulses are delivered to the sample via the RF coils in the NMR probe. These RF pulses generate an additional, temporary magnetic field, called B1 , which is orthogonal to the magnets primary B0 field. The magnetic component of the B1 field applies a torque to the nuclear spins, twisting them out of alignment with B0. Each RF pulse has a specific frequency, width, and shape, which modulates the B1 field to elicit different kinds of information from the sample.

    Fourier Transform is performed to convert the FID signal to a spectrum.

    Convert the FID into a spectrum. The signals detected by the probe are sent from the console to the host computer where they are converted from the time-domain into the frequency-domain through a process known as Fourier Transformation (FT). This process results in what users see as an NMR spectrum. The location, shape, and area of the signals in each spectrum provide spatial and connectivity information about the nuclei in the sample.

    Nuclear spins in a collection of ethanol molecules an intermediate time after B1 is off. Free induction decay

    (FID) occurs as the spins relax.

    Measure the Free Induction Decay (FID). The FID is the signal produced by the sample as the

    nuclear spins in the sample relax back to their original state of alignment with B0. This decay

    occurs within a few seconds and is captured as a function of signal intensity versus time.

    Nuclear spins at equilibrium in a collection of ethanol molecules in magnetic field B0.

    Place the sample in the magnet. The sample is inserted into the center of the magnet where the homogenous magnetic field B0 aligns the spins of the nuclei in the sample. The sample

    sits inside an NMR probe, and the NMR probe is surrounded by the superconducting magnet.

    For Research Use Only. Not for use in diagnostic procedures.This information is subject to change without notice.

    Agilent Technologies, Inc. 2013 Printed in the USA November 1, 2013

    5991-3206EN