Radical anions of polysilane derivatives studied by pulse radiolysis

The electronic structure of polysilane charged radicals has been studied by transient absorption spectroscopy using nano-second pulse radiolysis techn ique. Radical anions of polysilanes with symmetric alkyl, and asymmetric al kyl, and phenyl substituents displayed a near-UV absorption band with a 0-0 .5 eV red shift from absorptions ascribed to exciton states. A near-IR tran sient absorption was also observed with the same kinetics as: the UV band. Electron transfer from polysilane radical anions to pyrene was observed wit h rate constants from 4.5 x 10(9) to 7.3 x 10(9) M(-1)s(-1) Extinction coef ficients (epsilon(.-)) of the radical anions were determined to be 8.5 x 10 (4) 1.6 x 10(5) M(-1)cm(-1). The value of E(.-) and band width of the trans ient absorption depended on the substitution of the Si main chains. The deg ree of electron delocalization was estimated based on the 1-D polaron model , and showed a clear relationship M with the extinction coefficient epsilon Of the band-gap transition and the viscosity index a of the polymers. (C) 2001 Elsevier Science Ltd. All rights reserved.