Optic nonlinearities of a copper complex of pyrazinoporphyrazine

For the copper complex of pyrazinoporphyrazine AzaPhcCu(C(CH3)(3))(8) in CH2Cl2, we use nanosecond pulses to measure its third-order nonlinear optic effects at 532 nm. The results show that its effective third-order nonlinear refractive index n(2)(eff) (-7.85 x 10(-10) esu) is larger than that of the AzaPhcCu(C12H25)(4) and the CuPc(OC5H11)(8). The reverse saturable absorption (RSA) of AzaPhcCu-(C(CH3)(3))(8) is demonstrated by the ratio of effective excited state to ground state absorption cross sections. The observed intersystem crossing lifetime tau(isc) of AzaPhcCu(C(CH3)(3))(8) (similar to 15 ns) and AzaPhcCu(C12H25)(4) (similar to 45 ns) are longer than that of CuPc(OC5H11)(8) (similar to 5.0 ns). The aza-substituents are suggested to form a S-1(n, pi*) state as their lowest excited singlet-states, and their radiationless intersystem crossing rates (1/tau(isc)) are discussed with the spin-orbit coupling [psi(S)|\H-SO\psi(T)] and the vibronic coupling [chi(S)|chi(T)] effects between S-1 and T-1 states.