PHOTOPHYSICS OF POLY(METHYLPHENYLSILOXANE) MONOMERIC MODEL COMPOUNDS

Steady-state spectra (fluorescence, excitation, and absorption) and fl uorescence decay of several substituted alkoxysilanes were measured in a broad range of temperatures, -100 to 50 degrees C. Special emphasis was put on compounds which are potential models for the repeat unit i n poly(methylphenylsiloxane). In the absorption spectra, the vibration al resolution and the molar absorptivity (at maximum absorbance) depen d very much on the type of groups joined to the silicon atom. Fluoresc ence decays were monoexponential at any temperature. Both the lifetime and the fluorescence intensity show a non-Arrhenius dependence at the low temperatures. Some conclusions were derived on the choice of a pr oper monochromophoric model compound for a polychromophoric chain.