Heavy atom effect on nonlinear absorption and optical limiting characteristics of 5,10,15,20-(tetratolyl) porphyrinato phosphorus (V) dichloride

Abstract

Optical limiting performance and third-order nonlinearity χ(3) are investigated in 5,10,15,20-(tetratolyl) porphyrinato phosphorus (V) dichloride ([(TTP)PVCl2]+). Heavy atom effect exerted by the two axial chlorides is found to result in low fluorescence yield (∅fl), shorter lifetimes of S1, T1 and faster intersystem crossing (ISC), leading to larger excited state absorption (ESA) from T1 → Tn. This phenomenon is found to lower the limiting threshold by 30 times and increase the second hyperpolarizability by one and three orders in ps and ns time regimes, respectively. © 2002 Elsevier Science B.V. All rights reserved.