Nonlinear absorption of new mesoionic compounds

The nonlinear absorption of new mesoionic compounds (MIC) was investigated using nanosecond laser pulses with wavelengths at 570, 605 and 618 nm. Nonlinear absorption cross-sections, σ2 ≈ 10−45 cm4 s/photon, larger than any recorded in the literature, were obtained due to the introduction of p-CF3–C6H4 electron-acceptor and p-CH3–C6H4 or p-CH(CH3)2–C6H4 electron-donor groups in the MIC ring. The large values of σ2, the ease of synthesis of these compounds and their marked stability, make them promising candidates for photonic applications.