Chromophore techniques, nonlinear light

There have also been reports on the preparation of polar materials by a photo-electro-poling technique that combines the optically induced quadrupolar depletion of chromophores in the direction of the light electric vector with an additional field-induced orientation of dipolar chro-mophores. The latter allows the preparation of cold electrets, which are interesting for nonlinear optical applications, such as optical harmonic generation, wave mixing, etc. ... 

Two-photon absorption spectra (650-1000 nm) of a series of stilbene chromophores were measured via a newly developed nonlinear absorption spectral technique based on a single and powerful femtosecond white light continuum... 

Some APIs and most counterions laclc or have only a weak chromophore, so that absorbance detectors cannot be used. At present, such analytes are typically detected by aerosol-based detection techniques such as evaporative light scattering and charged aerosol detection. Both detection techniques have already been described in Section 8.3. CAD has been shown to overcome many of the issues found with ELSD. CAD is more sensitive, has a wider dynamic range and better precision, and, although response is nonlinear, calibration is less complex than with ELSD. 

---