Transient nonlinear optical response of some symmetrical nickel dithiolene complexes

The transient nonlinear optical response of some recently synthesized symmetric nickel dithiolene complexes, namely the Ni(etodddt)2 (etodddt = 4,5-(1,4-oxathiane-2,3-diyldithio)-1,3-dithiole), the Ni(pddt)2 (i.e., bis(6,7-dihydro-5H-[1,4]dithiepine-2,3-ddithiole) nickel)) and the Ni(dddt)2 (bis(5,6-dihydro-1,4-dithiine-2,3-dithiole) nickel), is studied using Z-scan technique employing 1064 and 532 nm, nanosecond laser pulses. The absorptive and the refractive parts of the third-order susceptibility χ(3) were determined and the second hyperpolarizability γ of each dithiolene complex was deduced at both excitation wavelengths, while strong resonance enhancement was found to occur under 1064 nm excitation. The present results are discussed and compared with other literature results obtained on similar symmetric and unsymmetric dithiolene complexes.