Only one spectrum can be displayed per window, however, several windows can be opened at once. Start by opening an NMR method. Save the file frequently so that your changes are not lost. The shim is saved along with the sample. Shimming Since NMR is based on exposing the nuclei of a sample to magnetic fields, it is important to create highly homogenized field strengths in the solenoid prior to taking a spectrum.
Homogeneity provides for the greatest resolution, sensitivity, and reproducibility.
These small currents cause small magnetic fields that adjust inhomogeneities in the primary magnetic field created by the solenoid. The goal in shimming is to get the lock signal as high as possible. The lock sweep is seen on the console monitor. Any shim adjustment that raises the signal is good but each shim variable is affected by the others. It is important not to select shim values that would alter the sweep so much that the magnet will be so far out of shim that the lock is lost.