Repetition rate Ernst angle

In the basic ATP sequence the combination of 90° excitation pulse and high repetition rates leads to intensity loss due to the incomplete relaxation. Therefore before discussing specific extensions to the APT sequence it is of interest to consider replacing the 90° excitation pulse with a pulse adapted to the Ernst angle condition in a similar manner as for one-pulse experiments. However simply replacing the 90° pulse by an Ernst pulse angle fails because the spin echo is based on a complete transfer of the z-magnetization into x- or y-coherence. Consequently it is necessary to append a second... 

---