Engineering the ground- and excited-state absorption spectra of broadband reverse saturable absorbers

We exploit the strong spin-orbit coupling in iridium to modify the linear absorption spectrum of a novel iridium(III) complex so as to broaden the spectral region over which it exhibits reverse saturable absorption. We discuss the design of the new chromophore, present its ground-state absorption spectrum, and report values of its singlet excited-state lifetime and singlet and triplet excited-state absorption cross sections, determined from femtosecond transient difference absorption measurements and nanosecond and picosecond open-aperture Z scans.