Surface Quasi-Elastic Light Scattering SQELS

4 SURFACE QUASI-ELASTIC LIGHT SCATTERING (SQELS) 

A liquid surface is continually roughened by thermal excitations, which give rise to the hydrodynamic modes known as capillary waves. The r.m.s. amplitudes of the waves are small ( 2 A) but they are efficient light scatterers. The displacement of the liquid surface from its equilibrium position by a wave propagating in the X direction is  

To date much of the work published on SQELS from spread polymers has emanated from Yu and colleagues [62-65], but assumed that the viscous moduli are zero. 

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