Time-resolved measurement of the stimulated emission Stokes shift in LDS750: Evidence for inhomogeneous relaxation kinetics

Abstract

The fluorescence spectrum of LDS750, a polar organic molecule, is measured as a function of time subsequent to its excitation using transient stimulated emission spectroscopy. At early time, the emission profile of LDS750 is dependent on the excitation energy, while at long times it is not. The evolution of the steady-state fluorescence spectrum is seen to occur as a result of inhomogeneous relaxation kinetics in the emission band rather than via a uniform red shift of a single feature. The individual features giving rise to the observed spectral dynamics are a consequence of an end-group photoisomerization of LDS750.