Value and phase of the third order susceptibility

From DFWM measurements x was determined for several polydiacetylenes in the near-resonant to off-resonant wavelength region, 680 nm to 750 nm (Tab. 9.6). Concurrently, the 

The value of is nearly identical for p-TS6 and p-4BCMU, and 4 times lower for p-IPUDO. These values were reproducible within 30%. For p-FBS, the reproducibility was only within an order of magnitude. No difference was foimd between thermally and x-ray polymerised crystals [118]. 

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