ZZthe result will be a torqueof the magnetic moment-MzM from Z to Y with a 011angley1yB11MyB11111IZending the Bl application will result in arelaxationprocessXthe nuclei return to the equilibriumyrestoring the initial distributionthisrelaxationisdetectedandproduce theNMR signalIIREEA-NanjingAgricultural University/April 2008
y x z Mz the result will be a torque of the magnetic moment M from Z to Y with a θ angle ending the B1 application will result in a relaxation process the nuclei return to the equilibrium restoring the initial distribution y x z B1 y x z My θ B1 this relaxation is detected this relaxation is detected and produce the NMR produce the NMR signal IREEA-Nanjing Agricultural University/ April 2008
the relaxation is characterized by energy emission and a loss of phasecoherenceboth processes are detected and produce the NMR signaleach nucleus will relax with a circular pathZthereby producing a sinuoisodal FID (freeinductiondecay)XthisissignalInt.bycharacterizedIntensityversusTime domain-Timethemathematical FourierTransformation will convertthe FID in a classical NMRsignalIntensityversusfrequenciesFrequency domainIREEA-NanjingAgriculturalUniversity/April2008
the relaxation is characterized by energy emission and a loss of phase coherence both processes are detected and produce the NMR signal y x z each nucleus will relax with a circular path thereby producing a sinuoisodal FID (freeinductiondecay) this signal is characterized by Intensity versus Time domain Int. Time the mathematical Fourier Transformation will convert the FID in a classical NMR signal Intensity versus Frequency domain IREEA-Nanjing Agricultural University/ April 2008 frequencies
the intensity of radiofrequency Bl (MHz) is related to the intensity ofBO field (Tesla)B0=9.4 Tesla B1= 400 MHzB0=14.1 Tesla B1= 600 MHzthis affects the amplitude of resonance frequencies that willchange in different instrumentsB1=300Mhz signal=450HzB1=60Mhz2 signal=90Hzin order to compare the response of different instruments thefrequency resonances are divided for the applied B1 fieldHz/MHzthereby expressing the resonances of the nuclei inPpm (part per million)90Hz/60MHz x 106 1.5 ppm450Hz/300MHzx1061.5ppmIREEA-Nanjing Agricultural University/ April 2008
the intensity of radiofrequency B1 (MHz) is related to the intensity of B0 field (Tesla) this affects the amplitude of resonance frequencies that will change in different instruments B0=9.4 Tesla B1= 400 MHz B0=14.1 Tesla B1= 600 MHz in order to compare the response of different instruments the frequency resonances are divided for the applied B1 field Hz/MHz thereby expressing the resonances of the nuclei in Ppm (part per million) B1=60Mhz signal= 90Hz B1=300Mhz signal= 450Hz 90Hz/60MHz x 106 1.5 ppm 450Hz/300MHz x 106 1.5 ppm IREEA-Nanjing Agricultural University/ April 2008
?the electronic environment of each atom (for instance chemicalbond) will affects its magnetic properties (shielding effect) therebymodifying the frequency resonance of different atoms (chemicalshift)·this property allows to distinguish the different nuclei in theorganic molecule (aromatic. phenolic, aliphatic etc.)FID of 2-hydroxy-butyric acidOHO=C-CH-CH2-CH3OHIREEA-NanjingAgriculturalUniversity/April2008
•the electronic environment of each atom (for instance chemical bond) will affects its magnetic properties (shielding effect) thereby modifying the frequency resonance of different atoms (chemical shift) •this property allows to distinguish the different nuclei in the organic molecule (aromatic, phenolic, aliphatic etc.) FID of 2-hydroxy-butyric acid OH O=C-CH-CH2-CH3 OH IREEA-Nanjing Agricultural University/ April 2008
The NMR in solid state is characterized by the following drawbacksChemical Shift Anysotropy (CSA):depends on the orientation of the chemical bond respect to externalmagnetic field BO that will increase the range of chemical shift effectin liquid state the molecules are free to move (tumbling)each chemical bond will assume each possibleB0orientation respect to BO thereby averaging toBzero the CSA effectSignal Amplitude < 1Hzin solid state the chemical bonds have fixed6=0orientation respect to B0HOOHthe electronic environments will produce a largeB0R-C=OCSA effect?10Signal Amplitude > 100 HzR
each chemical bond will assume each possible orientation respect to B0 thereby averaging to zero the CSA effect Signal Amplitude < 1Hz The NMR in solid state is characterized by the following drawbacks: Chemical Shift Anysotropy (CSA): depends on the orientation of the chemical bond respect to external magnetic field B0 that will increase the range of chemical shift effect B0 R-C=O OH R-C=O OH R C- =O OH R C- =O OH B0 OH R C- =O R - C = O O H R C- =O OH in solid state the chemical bonds have fixed orientation respect to B0 the electronic environments will produce a large CSA effect Signal Amplitude > 100 Hz in liquid state the molecules are free to move (tumbling)