Optical radiation cooperation

Polyacrylamide (Orcolon ) is mentioned primarily out of historical interest. It was produced by Optical Radiation Cooperation (ORC, Azusa, California, USA) as a purely synthetic substance composed of polyacrylamide, a polymer of acrylamide, and was used for years in electrophoresis and chromatography. It is made out of long carbon chains, such as seen in fatty acids or carotenes, and does not need to be stored at cool temperatures. 

The plot of the optical yield, Gcmax, of the eso] when plotted vs. the DMSO molar fraction has a broad minimum between 0.43 and 0.93 mole fraction DMSO. It is unlikely that the minimum in G ma). arises from a minimum in smal alone (especially as AIT was found to be nearly constant over the full range) and it seems more reasonable that the main reason is a minimum in the radiation yield, G. Cooper and coworkers30 suggested that the minimum in G(esol ) is the result of a decreased fraction of the free electron which become solvated. 

The ASE process occurs in a gain medium whenever the optical confinement is superior, or the decoherence time is short (Section 22.2). The confinement can be described by the radiation leakage rate k, whereas the cooperation among chromophores may be quantified by the Arrechi-Courtens time [112] Tc, which is inversely proportional to the chromophore density in the medium. The value of (kTc) accounts for the relative number of photons emitted by the ASE process [96]. This happens in both polymer solutions (in a cuvette), or in neat polymer films of thickness 100 nm deposited on glass substrates due to optical confinement formed by the film waveguiding properties. 

ASE process [96]. Therefore, in the case of strong optical confinement, where kt < 1, ASE is the dominant radiation process. On the other hand, for weak optical confinement where kt > 1, cooperative... 

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