Nonresonant Saturation Absorption in Electrostatic Self-Assembly Films Containing Methanofullerene

Ultrathin films containing methaofullerene are prepared by electrostatic layer-by-layer self-assembly of a positively charged trifluoroacetic acid salt of monoamino-substituted methanofullerene (TMAF) derivative and a negatively charged poly (sodium 4-styrenesulfonate) (PSS). Absorptive optical nonlinearities of 30 bilayer TMAF/PSS films and TMAF in water solution are measured using the Z-scan technique at 532nm. Nonresonant saturation absorption is observed in the film sample, whereas reverse saturation absorption was for TMAF in water. The saturation-absorption behaviour is interpreted by a special formula. The saturation intensity is extracted to be 15.2±0.8MW/cm². The mechanism of saturation absorption in the TMAF/PSS film is discussed.