Critical Opalescence of Polystyrene Solutions

McIntyre, D.; Wims, Andrew M.; Green, M. S.

doi:10.1063/1.1733145

Cited by 18 publications

(3 citation statements)

References 4 publications

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“…Polystyrene has been extensively used in the literature, and both its physical and optical properties are well known. [7][8][9][10][11][12][13][14][15][16][17] The results of these experiments confirm the earlier hypothesis and show that the measured absorption crosssection depends on the thickness of the multilayer particle ''film'' in a way that can be explained by the EFSW. Given the likelihood of this explanation, we also discuss the potential for correcting measurements made with our original specular reflection approach to give cross-sections that are comparable to those from traditional aerosol methods.…”

Section: Introductionsupporting

confidence: 81%

“…Thickness and Refractive Index of Particle Multilayers. Studies on the creation of artificial opals and diffraction effects [7][8][9][10][11]15 show that spherical particles may form closepacked fcc lattices under certain conditions. Due to our method of sample preparation, our samples were not found to be closepacked at either monolayer or multilayer coverages.…”

Section: Methodsmentioning

confidence: 99%

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A Study of Electric Field Standing Waves on Reflection Microspectroscopy of Polystyrene Particles

et al. 2009

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We have been investigating the mid-infrared (MIR) reflection spectrum of microparticles on mirrored substrates. Gold-coated porous alumina filters were used as a substrate to layer the particles and provide consistent reflection spectra. Polystyrene spheres with measured diameters of 0.42 microm were studied using Fourier transform infrared (FT-IR) reflection microspectroscopy, and spectra are shown for coverages in the range 0.5-6 monolayers (ML). Results show that absorption has a nonlinear, stairstep-like dependence on particle coverage and a wavelength dependence that can be explained by electric field standing waves (EFSW) caused by the mirrored substrate. The same effect is found to cause progressive weakening of the observed spectra as a function of increasing wavelength in sub-monolayer coverage measurements. Scattering effects in the spectra are consistent with surface scattering at the antinodes of the EFSW. These observations provide explanations for differences seen between optical properties of particles calculated using the specular-reflection method versus those calculated using traditional aerosol methods. A simple multilayer method for estimating particle absorption coefficients is demonstrated that compares well with values reported using ellipsometry for bulk polystyrene. Another simple method based on submonolayer coverage spectra provides spectra suitable for classification analysis but is only semi-quantitative at determining absorption coefficients.

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Section: Introductionsupporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

A Study of Electric Field Standing Waves on Reflection Microspectroscopy of Polystyrene Particles

et al. 2009

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“…While this term can qualitatively account for some of the temperature behavior demonstrated by D and c/AR(6), it does not provide information on the angular distribution of scattered light or on the existence of a slow relaxation mode. Excess scattered intensities similar to those of PEOX solution a few degrees from the phase transition have also been observed in other polymer-solvent systems.12•15'17'60" 52 The appearance of a slow relaxation mode in dynamic scattering in the accompaniment of excess low-angle scattering seems to be associated with the development of long-range spatial and temporal concentration fluctuations36 that would eventually drive the system toward a macroscopic phase separation.…”

Section: Discussionmentioning

confidence: 70%