Fluorescence of cyclotetrasilanes in rigid glass at 77 K, a remarkably large Stokes shift

Abstract

The fluorescence of cyclotetrasilanes with an extremely large Stokes shift (up to 13700 cm^–1) has been observed in rigid matrices at 77 K. The large Stokes shift is interpreted in terms of variation in potential energy for the S₁ and S₀ states as a function of the ring Si–Si bond distance. Fluorescence properties are dependent on the molecular structures (planar and bent forms) of the compounds; the fluorescence quantum yield, lifetime, and Stokes shift for the former are greater than those for the latter.