Concentration-dependent two-photon absorption and subsequent excited-state absorption in 4-methoxy-2-nitroaniline

Abstract

By performing both open-aperture Z -scan and transient transmission measurements with femtosecond laser pulses in the near infrared region, the concentration dependence of two-photon absorption (2PA) and subsequent excited-state absorption (ESA) are investigated in acetone solution of 4-methoxy-2-nitroaniline (4M2N). Owing to the high tendency of forming aggregation molecules in solution, a considerable dependence of the nonlinear optical response on the concentration is observable at a 4M2N concentration of 10-3 M and beyond. It is found that both effective 2PA and ESA cross sections decrease with increasing concentration, while the effective lifetime of 2PA-induced excited states lengthens. © 2009 American Institute of Physics.