Photoluminescence study of photodegradation of polysilanes

Photodegradation in poly(methylphenylsilane) (PMPS) and poly(di-n-hexylsila ne) (PDHS) films was studied by absorption and luminescence spectroscopy at T=295 and 5 K as function of wavelength, lambda (irr), and duration of UV- irradiation, t(irr). It was shown that irradiation, at longer wavelengths r esults in the scission of the longest segments of the polymer chain, while the short-wavelength irradiation leads to the scission of both the short an d the long segments. This is due to competing processes of scission of shor t segments and energy transfer to long segments. The conformational transfo rmation of polymer chain of irradiated PDHS from trans-conformation into he lix-conformation has been found.