Nonlinear spectrometer for characterization of organic and polymeric molecules

We have developed a femtosecond continuum spectrometer to measure nonlinear absorption spectra from 300 nm in the UV to 1.7 micrometers in the IR. This method is applied for measuring NLA spectra of semiconductor, organic and polymeric materials. The pump-probe nature of the experiment also allows the temporal response to be determined, thus helping in the determining of the underlying physical mechanisms for the nonlinearity. We describe studies of two-photon absorption in a series of alkyl fluorenes and excited state absorption dynamics in a series of polymethines using this spectrometer.