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NMR Spectroscopy

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NMR Spectroscopy Prepared by: Joy Lapinig Karen Mae Laid Rhea Villacampa Introduction There are two general types of NMR instrument; continuous wave and Fourier ... – PowerPoint PPT presentation

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Title: NMR Spectroscopy


1
NMR Spectroscopy
  • Prepared by
  • Joy Lapinig
  • Karen Mae Laid
  • Rhea Villacampa

2
Introduction
  • There are two general types of NMR instrument
    continuous wave and Fourier transform. Early
    experiments were conducted with continuous wave
    (C.W.) instruments, and in 1970 the first Fourier
    transform (F.T.) instruments became available.
    This type now dominates the market.

3
Continuous Wave NMR Instruments
Continuous wave NMR spectrometers are similar in
principle to optical spectrometers. The sample is
held in a strong magnetic field, and the
frequency of the source is slowly scanned (in
some instruments, the source frequency is held
constant, and the field is scanned).
4
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5
Fourier transform NMR Instruments
  • The magnitude of the energy changes involved in
    NMR spectroscopy are small. This means that
    sensitivity is a major limitation. One way to
    increase sensitivity would be to record many
    spectra, and then add them together because
    noise is random, it adds as the square root of
    the number of spectra recorded. For example, if
    one hundred spectra of a compound were recorded
    and summed, then the noise would increase by a
    factor of ten, but the signal would increase in
    magnitude by a factor of one hundred - giving a
    large increase in sensitivity. However, if this
    is done using a continuous wave instrument, the
    time needed to collect the spectra is very large
    (one scan takes two to eight minutes).
  • In FT-NMR, all frequencies in a spectrum are
    irradiated simultaneously with a radio frequency
    pulse. Following the pulse, the nuclei return to
    thermal equilibrium. A time domain emission
    signal is recorded by the instrument as the
    nuclei relax. A frequency domain spectrum is
    obtained by Fourier transformation.

6
HISTORY
  • Felix Bloch and Edward Mills Purcell(1946)
    -1st to described independently the
    nuclear magnetic resonance (NMR).
  • -nobel price in physics in 1952
  • -then the NMR develop as a technique of
    analytical chemistry and biochemistry.
  • Richard R. Ernst(1991)
  • -Ft-NMR works by irradiating the sample,held
    in static external magnetic field .

7
Richard R.Ernst and Kurt Wuthrich(2002)
-developed 2 dimensional and multidimensional FT-N
MR into a powerful technique. Raymond Andrew
-pioneer the development of high resolution
solid state NMR. Alex Pines and John
Waugh Revolutionized the area w/ the introduction
of the cross polarization technique
8
Uses of Nuclear Magnetic Resonance
  • Magnetic resonance imaging for medical diagnoses
    and used in chemical studies, notably in NMR
    spectroscopy.
  • Extremely useful for analyzing sample
    nondestructively.
  • Used as data acquisition in the petroleum
    industry for petroleum and natural gas
    exploration and recovery.

9
Parts of the Magnet
  • Reflective Myler
  • Vacuum
  • N2 Reservoir
  • He Reservoir
  • Super conducting Solenoid

10
HOW NMR WORKS
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12
Steps in Preparing Samples
  1. Use the Correct Quantity of Material
  2. Remove all solid particles
  3. Make samples to the Correct Depth
  4. Use Deuterated Solvents
  5. Use clean Tubes and Caps
  6. Label Your Samples
  7. Use an Internal reference
  8. Degassing Samples

13
THANK YOU AND GOD BLESS YOU ALL!
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