PATROS - A new MAS exchange method using sideband separation: Application to poly(n-butylmethacrylate)

The tr-ODESSA method (Reichert et al., J. Magn, Reson, 125, 245 (1997)), wh ich is a 1D MAS experiment designed to monitor spin exchange involving both equivalent and inequivalent sites, is extended to situations where the spe ctrum consists of several spinning side band (ssb) manifolds with small che mical shift anisotropies, To increase the spectral resolution in such situa tions, the tr-ODESSA sequence is combined with that of PASS to a single exp eriment, which we term PATROS, In this hybrid experiment, magnetization tra nsfer is monitored by the tr-ODESSA part, while the increase in resolution is provided by the separation of the ssb according to their order, during t he PASS part. We demonstrate the feasibility of the method on a standard so lid dimethylsulfone (DMS) sample and then apply it to monitor separately th e ultraslow motions of the main- and side-chains in the polymer poly(n-buty lmethacrylate). Theoretical expressions for the ssb intensities in PATROS e xperiments are derived and the merits and limitations of the method are dis cussed. (C) 2000 Academic Press.