Nonlinear optical properties of thienyl and bithienyl iodonium salts as measured by the Z-scan technique

The linear and nonlinear optical properties for a series of thienyl- and bithienyl(aryl)iodonium triflate salts 1-4 have been determined. The energy of the linear absorption maxima for salts 2-4 experiences only a minor shift to lower energy as the aryl group is made more electron deficient. In contrast, the real parts of the second hyperpolarizabilities, gamma(R). experience a 10-fold increase. Open-aperture Z-scan data for all three bithienyl iodonium salts 2-4 demonstrate the presence of three-photon absorption under irradiation at 650 nm.