The electronic structure, UV-visible spectrum, excited states mol. dynamics and micro-mechanism of reverse saturable absorption of the Cu phthalocyanine (CuPc) mol. were studied by using the ROHF-INDO/SDCI method associated with experiment The necessary condition of reverse saturable absorption of CuPc is that the lowest quadruple state absorption cross section must be larger than the ground state absorption cross section for laser radiation. This condition is satisfied when the wavelength of incident laser radiation is 532 nm for CuPc, so that reverse saturable absorption occurs. The theor. analyses are consistent with experimental results.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, QUANTUM CHEMISTRY, EXCITED STATE, ELECTRONIC STRUCTURE, ZINC PHTHALOCYANINE, VISIBLE SPECTRUM