Mirror symmetric broadband homodecoupled perfect echo spectroscopy

A new experiment for recording phase sensitive ω₁-broadband homodecoupled TOCSY spectra is presented. The method is an extension of the already existing perfect echo (PE) filter, proposed to sample t₁ chemical shift under sustained homodecoupling. The modification is made by attaching a time reversed perfect echo filter to a regular perfect echo scheme. Thus it becomes possible to acquire for longer t₁ acquisition times without compromising the quality of homodecoupling. The mirror symmetric double perfect echo is implemented into the evolution period of a TOCSY experiment. A spin lock pulse purges undesired dispersive antiphase components at the end of the central t₁ evolution period. Pure absorptive lineshapes with reduced proton spin multiplicities are obtained. The approach can be used in conjunction with real or constant time chemical shift evolution. In case of compounds with reduced T₂ relaxation time, the real time approach is advisable, where the echo delays are an extension of the t₁ evolution period. In this way, an unnecessary loss due to T₂ relaxation is avoided. Using the pulse sequence in constant time mode at high t_1max values gives ω₁-homodecoupled TOCSY spectra without a significant dependence of the transfer amplitude on J. All experiments were carried out using non uniform sampling to decrease the measurement time. Experimental setup, advantages and limitations are discussed.