Criticality of fluorescence spectra of the nanosized polysilanes oriented in the mesoporous silica

The fluorescence and fluorescence excitation spectra of poly(di-n-hexylsilane) confined within mesoporous silica hosts have been studied in the temperature range from 5 to 150 K. The polymer chains incorporated into the 2.8-nm pores show visible fluorescence at 370-500 nm. We suggest that the fluorescence is caused by the transitions from the new distortion-related localized states. These states appear due to the surface induced orientation of polymer chains at contact with the pore walls in the silica. The symmetry break near such defects also leads to the emergence of a new band in the excitation spectrum centered at 300 nm.