Light scattering in discrete random media and related materials
Light scattering in discrete random media and related materials
By modelling white paint materials as discrete random media, a variety of methods can be employed to study the physics of their optical properties. The white paint model consists of an assembly of identical non-overlapping titanium dioxide (TiO2) spheres as scatters dispersed in a homogeneous medium with liquid-like correlations described by the Percus-Yevick hard sphere radial distribution function. From this model, the correlation effects and the crowding effects, or multiple scattering effects are regarded to the two dominant mechanisms which govern the scattering efficiency of TiO2 in white paint.
By considering the weak scattering limit where the multiple scattering effects can be neglected it is possible to show that structural consideration is important in the understanding of the optical performance of white paint. The correlation and multiple scattering effects are combined in the Quasi-Crystalline Approximation (QCA) to demonstrate the inseparability of the two mechanisms in strongly scattering one component systems. The QCA is then extended to consider the effects of coating the scatterers, adding extenders and air voids. The results can be used to aid and gauge industrial attempts to maximise the scattering efficiency of TiO2.
Finally, the Coherent Potential Approximation (CPA) is employed in the paint context. The CPA results are compared with the QCA results to consider the applicability of the CPA since it is comparatively easier to implement and apply.
University of Southampton
1998
Ooi, Kean Hong
(1998)
Light scattering in discrete random media and related materials.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
By modelling white paint materials as discrete random media, a variety of methods can be employed to study the physics of their optical properties. The white paint model consists of an assembly of identical non-overlapping titanium dioxide (TiO2) spheres as scatters dispersed in a homogeneous medium with liquid-like correlations described by the Percus-Yevick hard sphere radial distribution function. From this model, the correlation effects and the crowding effects, or multiple scattering effects are regarded to the two dominant mechanisms which govern the scattering efficiency of TiO2 in white paint.
By considering the weak scattering limit where the multiple scattering effects can be neglected it is possible to show that structural consideration is important in the understanding of the optical performance of white paint. The correlation and multiple scattering effects are combined in the Quasi-Crystalline Approximation (QCA) to demonstrate the inseparability of the two mechanisms in strongly scattering one component systems. The QCA is then extended to consider the effects of coating the scatterers, adding extenders and air voids. The results can be used to aid and gauge industrial attempts to maximise the scattering efficiency of TiO2.
Finally, the Coherent Potential Approximation (CPA) is employed in the paint context. The CPA results are compared with the QCA results to consider the applicability of the CPA since it is comparatively easier to implement and apply.
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Published date: 1998
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Local EPrints ID: 464105
URI: http://eprints.soton.ac.uk/id/eprint/464105
PURE UUID: c12c3e61-ee0e-48b9-889f-d0f372822aba
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Date deposited: 04 Jul 2022 21:18
Last modified: 04 Jul 2022 21:18
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Author:
Kean Hong Ooi
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