Effective stimulated emission and excited state absorption measurements inthe phenylene-vinylene oligomer (1,4-bis-(alpha-cyanostyryl)-2,5-dimethoxybenzene))

The pump probe technique was used to measure the effective stimulated emiss ion and excited state absorption cross-sections of the phenylene-vinylene o ligomer (1,4-bis-(alpha-cyanostyryl)-2,5-dimethoxybenzene) dissolved in tol uene for different probe wavelengths. The effective stimulated emission cro ss-section was calculated from sigma(SE-eff) = sigma(SE) - sigma(ESA) and f ound to be positive. The possible laser tuning ranges have been determined. The spectral and temporal behavior of the optical transitions were investi gated. The dynamics of these optical transitions permitted direct measureme nts of the lifetime of the lowest triplet state, and was found to be of the order of 11 ms. (C) 1999 Elsevier Science B.V. All rights reserved.