Ring-flip motion of poly p-phenylene vinylene

1 Ring-flip motion of poly(p-phenylene vinylene) 

Quadrupole echo lineshapes for the phenylene ring-flip motion (or any jump model) are simulated with an n-site exchange calculation one must also include the exchange-caused relaxation between the pulses (echo distor- 

Spectra can be simulated with a superposition of ring-flip spectra whose rates, fc, are defined by a log-Gaussian distribution, P(log(/c))  

Each spectrum yields two parameters, a median jump rate, /cq and a log-Gaussian width Alog(fco). An activation energy, can be obtained from an Arrhenius plot of the jump rate. Typically, the distribution of jump rates is attributed to a distribution of activation energies and 

Notably, a small distribution of activation energies can cause a large distribution of rates. 

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