Characterization of nonlinear absorption in phosphine-substituted bithiophenes

The two-photon absorption cross-sections of two novel derivatives of 5,5'-bis(diphenylphosphino)-2,2'-bithiophene have been measured using Z scans employing 27-ps pulses at multiple pulse energies, yielding values of 1500 plusmn 50 GM and 2830 plusmn 50 GM.