The mixed metal cluster (n-Bu 4N) 2[MoCu 3OS 3(NCS) 3]: the first example of a nest-shaped compound with large third-order polarizability and optical limiting effect

Abstract

A mixed metal nido-cluster, (n-Bu 4N) 2[MoCu 3OS 3(NCS) 3], was discovered to exhibit large third-order polarizability (γ) and optical limiting effect. This is the first example of a nest-shaped compound with large nonlinear optical coefficients. The magnitude of the third-order polarizability, ¦γ¦= 4.8 × 10 −29 esu, was determined with 7-ns laser pulses of 532 nm wavelength by a degenerate four-wave mixing technique. An irradiance-dependent transmission measurement was conducted to assess the contribution of nonlinear absorption to the γ value. These results, in combination with those of a Z-scan experiment, yielded a negative value for the real part of γ, Reγ = −4.8 × 10 −29 esu. The negative sign of Reγ reveals that the nido-cluster has an interesting optical self-defocusing property. The optical limiting effect of the cluster was also demonstrated.