Lineshape

The lineshape refers to the symmetry and roundedness of an NMR peak. Most resonances arising from solutions have an intrinsic lineshape called a Lorentzian, which is symmetric, with fairly steep sides and a slow approach to the baseline. However, some experimental problems can also lead to changes in lineshape. Asymmetric lineshapes can arise from the presence of an unresolved peak, from poor sample preparation (particularly the inclusion of undissolved material or concentration gradients), or from poor shimming.