by fast T2(or T1) relaxation, leaving the antiphase signal not enough time to evolve into detectable magnetizatOn This phenomenon can also be explained in the frequency dimension: short acquisition times or fast relaxation leads to broad lines, which results in mutual partial cancelation of the multiplet lines in the case of an antiphase signal The simulation(next page) shows the dublet appearances for different ratios between coupling constant J and linewidth(LW). The linewidths were set constant to 2 Hz(at half-height), so that the different intensities of the dublet signal are only due to different J values Obviously, the apparent splitting in the spectrum can differ from the real coupling constant, if the two dublet lines are not baseline separated: for in-phase dublets, the apparent splitting becomes smaller, for antiphase dublets it is large than the true J value Ratio j/: 10 True J value hz 20.0 6.0 2.0 0.7 -phase sp litter 20.0 6.0 1.8 Antiphase splitting 20.0 6.0 2.2 1.3 In the basic COsY experiment the diagonal signals are in-phase and the cross-peaks antiphase, so that signals with small J couplings and broad lines(due to short AQ or fast relaxation) will show huge diagonal signals, but only very small or vanishing In the DQF-COSY, both types of signals stem from antiphase terms, so that both the cross-and diagonal peak intensity depends on the size of the coupling constants47 by fast T2 (or T1) relaxation, leaving the antiphase signal not enough time to evolve into detectable magnetization. This phenomenon can also be explained in the frequency dimension: short acquisition times or fast relaxation leads to broad lines, which results in mutual partial cancelation of the multiplet lines in the case of an antiphase signal. The simulation (next page) shows the dublet appearances for different ratios between coupling constant J and linewidth (LW). The linewidths were set constant to 2 Hz (at half-height), so that the different intensities of the dublet signal are only due to different J values. Obviously, the apparent splitting in the spectrum can differ from the real coupling constant, if the two dublet lines are not baseline separated: for in-phase dublets, the apparent splitting becomes smaller, for antiphase dublets it is large than the true J value. Ratio J/L: 10 3 1 1 /3 True J value [Hz} 20.0 6.0 2.0 0.7 In-phase splitting 20.0 6.0 1.8 n/a Antiphase splitting 20.0 6.0 2.2 1.3 In the basic COSY experiment the diagonal signals are in-phase and the cross-peaks antiphase, so that signals with small J couplings and broad lines (due to short AQ or fast relaxation) will show huge diagonal signals, but only very small or vanishing cross-peaks. In the DQF-COSY, both types of signals stem from antiphase terms, so that both the cross- and diagonal peak intensity depends on the size of the coupling constants