Light scattering, laboratory experiments

The authors thank the U.S. Army Research Office for financial support of this research at TCU and SMU. The light scattering and the thermal analysis experiments were conducted, respectively, by Dr. G.L. Hagnauer (Army Materials Technology Laboratory, Watertown, MA) and Dr. J.J. Meister (SMU). 

It might seem at first glance that arriving at the dipole moment p of an ellipsoidal particle via the asymptotic form of the potential < p is a needlessly complicated procedure and that p is simply t>P, where v is the particle volume. However, this correspondence breaks down for a void, in which P, = 0, but which nonetheless has a nonzero dipole moment. Because the medium is, in general, polarizable, uP, is not equal to p even for a material particle except when it is in free space. In many applications of light scattering and absorption by small particles—in planetary atmospheres and interstellar space, for example—this condition is indeed satisfied. Laboratory experiments, however, are frequently carried out with particles suspended in some kind of medium such as water. It is for this reason that we have taken some care to ensure that the expressions for the polarizability of an ellipsoidal particle are completely general. 

Acknowledgment. The research work of Jiang s group mentioned in this review has been supported by the National Natural Science Foundation of China (No. 28970183, 29374156, 29574154) and the National Basic Research Project-Macromolecular Condensed State. The light-scattering experiments were carried out in Prof. Chi Wu s laboratory at the Chinese University of Hong Kong. 

Acknowledgment for support of this research is made to the National Science Foundation (Grant CBT 8412604), the Blandin Foundation, the Graduate School of the University of Minnesota, the Minnesota Agricultural Experiment Station, and the University of Minnesota Computer Center. The authors are indebted to Professor V.A. Bloomfield, Department of Biochemistry at the University of Minnesota, in whose laboratories the light scattering measurements were carried out. 

It is actually rather easy to perform such an experiment in the laboratory and visualize by light scattering and spectroscopy the formation of the aggregates and the entrapment. The so-formed structure has an aqueous core separated from the aqueous environment by a lipid bilayer, and the analogy with a biological cell is apparent. 

Intensity fluctuation spectroscopy was used in our laboratory to study the dynamic behavior of surface ripples on thin liquid films. Both squeezing and bending modes were examined. To our knowledge one other group of researchers has obtained dynamic light-scattering data from thin soap films but as far as we know, nothing has been published in the official literature. Also some experiments were reported on lipid bilayers in water. ... 

Consequently Jf is determined by the velocities of the solutes relative to that of the solvent. In any experiment (including light scattering), it is the absolute fluxes Ji, that is, the fluxes of the solutes relative to some laboratory-fixed coordinate frame that are measured and not the relative flux Jid. Theory, however, deals with the relative flux Jid. It will thus be necessary after the calculation to transform J d back to the laboratory-fixed flux. We shall deal with this later. 

Static light scattering Experiments were performed in glass cuvettes (0=21 mm) at 25 C on a PL-LSP light scattering apparatus equipped with a 10 mW laser (633 nm), and LSP Version 4.0 software (Polymer Laboratories). Measurements were... 

Figure 1 illustrates the geometry of a typical laser light scattering experiment within a laboratory-fixed frame of reference x,y,z. 

---