The COSY 45 pulse sequence
Fig. 29 : Saccharine molecule
The example is given for the saccharine (Fig. 29).
The second impulsion is of 45°.
The drawback of this second pulse is to diminish the signal to noise ratio (Fig 17).
However it allows a more easy attribution of the signals of the spectrum in the cases of strong AB type coupling. In fact, the correlations spots near the diagonal are no more susceptible to be hidden by the auto correlation peaks (Spectrum 4).
Spectrum 4 : COSY 45°. We observe a strong diminution of the autocorrelation peaks.
Fig. 17 : Comparison of the COSY spectrum (upper part) and COSY 45 of an AMX type system