105 ROEe= roeex sin 0. sin e For all these offset corrections one needs to know just the spin-lock field strength used in the ROESY experiment, then the correction can be calculated automatically for each cross-peak individually Interference of noe and roe For ootc x 1, where there is no significant noe, this is all the correction that we need However, if that is not true, then we will simultaneously get NOE contributions from the z components of the locked magnetization(off-resonance, where the spin-lock axis tilts away from the transverse plane). So, the result of cross-relaxation during the spin-lock mixing time will be a combination of ROE and noe O:=ROE; sin 0 sin 0. NOE cos 0: cos 0 (in addition, all this is also multiplied with another sin 0, sin e for the projection onto the spin-lock axis and back) This is a severe complication because it depends not only on the easily calculated individual offsets in Fl and F2 (via the 0 values), but also on the ratio between NOE and roe, which depends on the exact correlation time t of the molecule Only for the extreme cases this correction is still relatively easy Note>> I NOE: ROE= 1 NOE. ROE=-2 For the sake of simplicity, ROESY spectra should only be quantitatively evaluated when there is no significant noe observed under the same conditions! TOCSY contributions yet another complication in ROESY spectra! The pulse sequences for ROESY and TOCSY are virtually identical, therefore it is obvious that toCsY transfer will also be observed in a ROESY experiment. This will, of course, only affect protons which have a mutual sclar coupling105 ROEtrue ROE ij ij i j = exp. sin sin 1 q q For all these offset corrections one needs to know just the spin-lock field strength used in the ROESY experiment, then the correction can be calculated automatically for each cross-peak individually! Interference of NOE and ROE For w0tc » 1, where there is no significant NOE, this is all the correction that we need. However, if that is not true, then we will simultaneously get NOE contributions from the z components of the spinlocked magnetization (off-resonance, where the spin-lock axis tilts away from the transverse plane). So, the result of cross-relaxation during the spin-lock mixing time will be a combination of ROE and NOE: sij = ROEij sin qi sin qj + NOE cos qi cos qj (in addition, all this is also multiplied with another sin qi sin qj for the projection onto the spin-lock axis and back). This is a severe complication because it depends not only on the easily calculated individual offsets in F1 and F2 (via the q values), but also on the ratio between NOE and ROE, which depends on the exact correlation time tc of the molecule. Only for the extreme cases this correction is still relatively easy: w0tc >> 1 : NOE : ROE = 1 w0tc << 1 : NOE : ROE = -2 For the sake of simplicity, ROESY spectra should only be quantitatively evaluated when there is no significant NOE observed under the same conditions! TOCSY contributions ... yet another complication in ROESY spectra! The pulse sequences for ROESY and TOCSY are virtually identical, therefore it is obvious that TOCSY transfer will also be observed in a ROESY experiment. This will, of course, only affect protons which have a mutual sclar coupling!