2D ROESY When the correlation time is close to te=/00. then no 0.5 modification of the NoESY experiment with a different 025,pc OE noe effects will be observable. However. there is dependence of the NOE on ootc 00 In the roesy( Rotating frame NOESY)experiment, the NOE (or better, the rOe)is always positiv, i.e., the 6/b0 ROE croSs-peaks have the opposite sign as the diagonal peaks. And it never becomes zero log (oot) The pulse sequence for the ROESY experiment is relatively simple: it is identical to the TOCSY sequence! After the first 90 pulse and the ti time, a spin-lock sequence follows during which the ROE builds up, exactly as the noe during the mixing time tm of the Noesy t1 spIn-lock In the rOESY experiment, relaxation does not occur in the static Bo field along the z axis, but in the transverse field generated by the r.f. irradiation: the non-equilibrium transverse component(e.g, IIx) relaxes with TIp while"frozen"in the spin-lock field, thereby generating a transverse component I2xin neighbouring spins by cross-relaxation With the exception of the different dependence on correlation time, everything else works like for the NOE: again, the initial ROe build-up rate shows a r dependence, but with longer mixing(=spin- k)times, the build-up becomes non-linear, and indirect ROEs start to occur. And, like in the NOESY, dispersive antiphase peaks can occur that are not caused by roe, but by scalar coupling However, while the NOESY experiment is rather straightforward to evaluate, there are several dditional problems to be considered with the roeSy offset dependence of the roe and interference between NOE and roe TOCSY contributions in the roesy spectrum103 2D ROESY When the correlation time is close to tc = 1 /w0 , then no NOE effects will be observable. However, there is a modification of the NOESY experiment with a different dependence of the NOE on w0tc : In the ROESY (=Rotating frame NOESY) experiment, the NOE (or better, the ROE) is always positiv, i.e., the ROE cross-peaks have the opposite sign as the diagonal peaks. And it never becomes zero! The pulse sequence for the ROESY experiment is relatively simple: it is identical to the TOCSY sequence! After the first 90° pulse and the t1 time, a spin-lock sequence follows during which the ROE builds up, exactly as the NOE during the mixing time tm of the NOESY. In the ROESY experiment, relaxation does not occur in the static B0 field along the z axis, but in the transverse field generated by the r.f. irradiation: the non-equilibrium transverse component (e.g., I1x) relaxes with T1r while "frozen" in the spin-lock field, thereby generating a transverse component I2x in neighbouring spins by cross-relaxation. With the exception of the different dependence on correlation time, everything else works like for the NOE: again, the initial ROE build-up rate shows a r -6 dependence, but with longer mixing (=spin￾lock) times, the build-up becomes non-linear, and indirect ROEs start to occur. And, like in the NOESY, dispersive antiphase peaks can occur that are not caused by ROE, but by scalar coupling. However, while the NOESY experiment is rather straightforward to evaluate, there are several additional problems to be considered with the ROESY: - offset dependence of the ROE and interference between NOE and ROE, - TOCSY contributions in the ROESY spectrum