I am continuing my explorations on board of my new multiplet simulator. It has been easy to simulate an asymmetric doublet. Here the asymmetry is only apparent and is due to the limited digitization.
As explained yesterday, the black line belongs to an experimental 2-D spectrum (today I have chosen a TOCSY), the red line is a theoretical doublet acquired and processed under the same conditions.
My simulator allows me to change the frequency by dragging the blue label at the bottom.
In this way the coupling remains constant. It turns out that my spectrum was a middle-range case. With a slight increase of the chemical shift I can obtain a symmetric doublet, or even a singlet!