nzene and a 4,4'-distyrylstilbene were investigated in solution and in the solidstate. Some notable features of the absorption and fluorescence spectra due to the structures and the phases (solution or solid) were observed, especially the Stokes shifts. Interesting photochemical behaviors in solution and in the solidstate were also found. While the (E,Z)-4-styrylstilbenes undergo a one-way photoisomerization