[Spectrum properties of Thulium bisphthalocyanine Langmuir-Blodgett films]

The configuration state and spectral properties of sandwiched thulium bisphthalocyanine (TmPc2) molecule in Langmuir films and Langmuir-Blodgett (LB) films were investigated by using the surface pressure-area (pi-A) isotherm and UV-Vis absorption spectra. The experimental results indicated that the sandwiched thulium bisphthalocyanine molecules form well-ordered stable monolayer films on the water/air interface, and the sandwiched thulium bisphthalocyanine molecules take the face to face orientation for the macrocycles and edge-on configuration in pure films, with the collapse pressure being 56 mN x m(-1). But the sandwiched thulium bisphthalocyanine molecules take the face-on configuration in the sandwiched thulium bisphthalocyanine films mixed with arachidic acid (AA), and the collapse pressure is more than 60 mN x m(-1). The sandwiched thulium bisphthalocyanine molecule could form well stable Langmuir films on sub-phase surface. The mixed TmPc2/arachidic acid not only could form well stable Langmuir films, but also could be transferred to solid substrate and deposited LB multilayers. In the chloroform solution and LB films of sandwiched thulium bisphthalocyanine, the UV-Vis absorption spectra have two absorption bands, namely Soret-bands and Q-bands. The electron orbit of sandwiched metal bisphthalocyanines was calculated by using absorption spectra VEH (Valence effective Hamiltonian) theory, and the electron transition orbit corresponding to the absorption peaks was analyzed. The Soret absorption band has two absorption peaks that are correlated with the electron orbital transitions of 184-187* and 178-186, and four absorption peaks of the Q absorption band are correlated with the electron orbital transitioned of 186-189*, 190* and 185-187*, 188*. In the LB films, the absorption peaks were red-shifted compared with those in the solution because of the interaction of molecules. The interaction of intra-layer molecules was stronger than that of interlayer molecules.