Photoisomerization of 1,1'-di-tert-butylstilbene (3) and 1,1'-dicyanostilbene (4) is monitored with stationary and broadband transient absorption spectroscopy. The electron affinity of the substituents correlates with the shift of the absorption band. The weak extinction of 3 complicates data interpretation, but comparison with earlier measured 1,1'-dimethylstilbene (1) and 1,1'-diethylstilbene (2) helps to assign transient spectra and relaxation paths. For 3 a long-lived perpendicular state P is observed with lifetime tau(P) = 134 ps in acetonitrile. For 4 tau(P) = 2.1 ps in acetonitrile and 27 ps in n-hexane, the difference indicating a substantial dipole moment (similar to 3D) of the P state. (C) 2016 Elsevier B.V. All rights reserved.