First and second derivative analysis of electroabsorption spectra inconjugated molecules and polymers:Stark shift and Stark broadening

摘要

Second-order Stark effect is analysed in terms of the third-order ono-linear susceptibility #alpha#~(3)(#omega#,#omega#,0,0) within a centroscymmetric one-dimensional three-level model.The Stark effect manifests iself in the electroabsorption spectrum mainly as the first or the second derivative ofthe unperturbed absorption spectrum that corresponds to either Stark shift or Stark broadening,respectively.Domination of the first or the second derivative in hte electrobasrption lineshape depends on the energy gap between the first dipole-allowed stateand a nearby excited dipole-forbidden state.The model takes into account inhomogeneous broadening and vibronic sidebands of both excited states.