Enter
jexp(1)
Obtain a normal proton spectrum
Place the cursor on the peak to be irradiated and enter
sd
This sets the decoupler at the frequency of the cursor. Write down the dof value. Repeat the same process, this time placing the cursor way downfield of your most downfield peak to obtain an off-resonance frequency. Write this frequency down as well.
Enter the following:
presat
dn='H1'
dps
satdly=10 (set this value to 7 times the longest T₁ if known, see Spin Lattice Relaxation Time (T₁) Determination for T₁ measurement directions)
d1=value of satdly-last # in the graphical pulse sequence
satpwr=-5 (or a value that results in approximately 80% reduction in the intensity of the irradiated peak, this can be found by trying different satpwr values and observing the % reduction in irradiated peak intensity.
ss=0
array='satfrq'
satfrq=most upfield freq, most downfield freq
dof=0
nt=16
gain?
gain=numeric value displayed after last command
bs=4
il='y'
go
This runs the NOE experiment.
To work the spectrum up and get a difference spectrum, do the following:
Enter
clradd
wft aph
adjust the spectrum phase if necessary
Enter
vs=3000 (this is an appox. value and varies depending on
intensities, DO NOT CHANGE THIS VALUE WITH
THE MOUSE OR OTHERWISE AFTER YOU SET IT HERE!!!)
ai
ds(1)
spadd
ds(2)
addi
CLICK ON "subtract"
CLICK ON "save"
jexp5
ds
You are now looking at the NOE difference spectrum and can use the usual peak picking and plotting commands to print out your difference spectrum and the intensities for each line. Remember not to change the vertical scale (vs) once it's set since the intensities depend on this value. The percent NOE is obtained by dividing the intensities of a given peak for the difference spectrum and the off-resonance irradiated spectrum. To get peak intensities in the off-resonance irradiated spectrum enter
jexp1
ds(2)
and use the usual peak picking, display and plotting commands.
Note that one can set up a NOE experiment which contains multiple peak irradiations. One finds all the desired irradiation positions and adds them to the satfrq array. When processing the data ds(1) and ds(2) in the above instructions need to be replaced by the appropriate array values for the on and off resonance irradiated spectra. Replace (1) and (2) with the indexes of the spectrum where the peak of interest was irradiated and the off-resonance spectrum, respectively. For example, assume 11 irradiations were done, the first 10 are on-resonance irradiations, the 11th is the reference (irradiated where there is no peak) and we are interested in the 5th spectrum. Complete the NOE workup as above but replace ds(1) and ds(2) with ds(5) and ds(11). Also note that the cyclenoe experiment (see Varian User Guide:Liquids NMR) can directly yield NOE difference spectra.
The above procedures can be used to measure spin saturation transfer also known as chemical exchange.