The 3 tensor components

The tensor component parallel to the polymer chain of about 2-3 x 10 ° esu (off resonant) is the well dominating source of the non-linear response. The DFWM signal was foimd to be polarized parallel to the polymer chain and the signal decreased below the detection threshold if any or all of the pump beams were polarized perpendicular to the chain. From these observations Xpirp can be estimated to be lower than 1 x 10 esu, i.e. at least a factor 

In the near-resonant frequency regime, a constant ratio of and die Unear absorption coefficient a has been found, as predicted by the PSF model [115]. This model provides the best description of the experimental results [120]. 

---