Heteronuclear J spectroscopy

In a study of heteronuclear J NMR spectroscopy, the radio frequency phase of the initial 90 Deg pulse was shifted together with the phase of the refocusing pulse. In heteronuclear spectra, the phase cycling method shifts all resonances by DF1 = (4Dt-1)-1 corresponding to 1/2 of the spectral width in the F1 frequency domain. Thus the proton transmitter can be set in the middle of the proton spectrum without introducing aliasing problems, and the technique does not interfere with ordinary quadrature detection, which is routinely used in the F-2 or P dimension. The phase-cycling scheme represents a simple alternative to the quadrupole phase detection proposed by R. R Ernst et al. (1978) since it does not require addnl. software for a hypercomplex Fourier transform. To eliminate the unmodulated component in the P spectra, the phase of the last 90 Deg proton pulse is alternated while the P free-induction decays are added and subtracted in alternate transients. Results are presented for Me3PO4 and 2'-guanosine monophosphate. [on SciFinder (R)]