Abstract The UV photolysis of teh permethylated linear polysilanes Me (Me 2 Si) n Me (I), with n= 4 to 8, in cyclohexane at, or al little above, room temperature has been found to proceed simultaneously by two different routes, one of these involves contraction of the chain with loss of dimethylsilylene species to produce octamethyltrisilane which was usually very resistant to the photolysis), while the other comprises homolytic scission of the silicon ...