Processing Data with VnmrJ

Typical Procedure

  • Select AcquireTab / AcquisitionPage and make note of number of points in F3 and increments in F1/F2
  • Select ProcessTab and “in t2” for 2D OR “in t3” for 3D experiment.
  • Apply window function by pressing “Gaussian” button.
  • Adjust phase as necessary using only left mouse number. (Note: rp should equal 0).
  • Now select “in t1” page (and/or “in t2” if 3D experiment)
  • From “AutoSetWeighting) popup select window function (i.e., Gaussian).
  • If you want to do linear prediction, check the checkbox and press “AutoLP x2” button.
  • You may set the transform sizes to 2x the number of points in that dimension, but the default may be OK.
  • Then under “Transforms” select Weighted -> “F2 x F1 2D” (or “F3 x F1 2D, etc.)
  • You may repeat for the 3rd dimension.

Other VNMR Processing Options

Solvent Subtraction
  • use as small a bandwidth as necessary (100 to 500)
  • coefs value from 100 to 200
  • don't bother trying polynomial function
  • offset only needed if tof not adjusted properly
Left Shift in frequence F1
  • can be used to apply a cicular shift on data collected with a small spectral width
Linear Predict 1st Point and extend data set
  • setlp2(desired ni2, acquired ni2, #fixed)
  • desired ni2 is the final extended data size
  • aquired ni2 is total # of increments used as a basis
  • # fixed is the # of initial points in t2 to be predicted (usually 1 to 4)
  • try with different # fixed to find best values
Baseline Correction in 2D
  • dc2d('f2') to correct for DC offsets along f2
  • applied after processing data
Baseline Correction in 3D
  • specdc3d is a string variable usually set to 'nnn'
  • set a character to 'y' to activate DC offset correction along a particular dimension
  • 1st character is for 1st dimension, etc
  • set before doing the 3D transform