Dimerization of Rhodamine B in Alumina sol and corresponding dip-coated film

Abstract The alumina sol doped with rhodamine B (RB) was concentrated to different degree and then dip-coated to prepare thin film. Dimerization of RB happens in the concentrated sol and the dip-coated thin film. As the sol concentrated, H-dimers are presented whereas in the dip-coated film J-dimers are displayed. When the dip-coated film is exposed to high humidity environment, J-dimer will transfer to H-dimer. Put the film in isopropanol vapor, J-dimer dissociates to monomer.