Mesoscale spatial distribution of electron spins studied by time-resolved small-angle and ultrasmall-angle neutron scattering with dynamic nuclear polarization; A Case of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) doped in high-density polyethylene

Kumada, Takayuki   ; Noda, Yohei; Koizumi, Satoshi; Hashimoto, Takeji

We carried out time-resolved small-angle neutron scattering studies of dynamically polarized high-density polyethylene (HDPE) doped with 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) persistent free radicals. We observed an enhancement of the scattering intensity by a factor of 100 in maximum after switching a microwave frequency. The enhancement was found to be due to concentration fluctuation of TEMPO, which generates heterogeneity of polarization with the length-scale of about 100 nm and scattering due to the heterogeneity. The length scale of the heterogeneity indicates that the TEMPO free radicals are localized more in non-fibrils but less in fibrils of HDPE.