Hi, I was asked to study polyethylene degradated by gamma and Xrays. I planed to measure relaxations rates, but which one is the most relevant to highlight chain degradation? T1, T2, but on 1H or 13C? By reading some articles, I feel T2 is not very interesting, right? T1rho experiments seems to give good results, I have found 2 sequences in Bruker's library, T1rhoX (CP step then variable length spin lock pulse on 13C channel) and T1rhoH (CP step then variable length spin lock pulse on 1H channel), and there is also the more classical variable contact time experiment, I don't know which one to use... Is there a more relevant relaxation rate to measure or should I try all of them and see which one gives good results ? I was also asked to study wood degradation in the same way. I have started to look for bibliography, but if anyone can suggest interesting articles... Thanks Anne