Spin probe dynamics in relation to free volume in crystalline organics from ESR and PALS: N-tridecane

A joint external probe ESR and PALS study on n-tridecane (n-TRD) using stable free radical 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) or ortho-positronium (o-Ps), respectively, is presented. In contrast to n-hexadecane (n-HXD) [Physica B 430, 99 (2013)], five crossovers in the spin probe TEMPO mobility coinciding with those in the o-Ps   probe annihilation parameters at the characteristic ESR and PALS temperatures in the solid phase were revealed: 1) acceleration within the slow regime at TX1slow in accordance with the changes in both o-Ps lifetime, τ3, and relative o-Ps intensity, I3, at Tb1cr* in the rigid crystalline solid are related to very local end methyl group dynamics, 2) slow to fast regime transition at T50G<