東華大學圖書館 |

Active Colloidal Self-Assembly With Optical Binding Forces /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Active Colloidal Self-Assembly With Optical Binding Forces // Dominique Davenport.
Author:	Davenport, Dominique,
Description:	1 electronic resource (112 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-02, Section: B.
Contained By:	Dissertations Abstracts International85-02B.
Subject:	Materials science. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29394974
ISBN:	9798380091541

Active Colloidal Self-Assembly With Optical Binding Forces /
Davenport, Dominique,

Active Colloidal Self-Assembly With Optical Binding Forces /Dominique Davenport. - 1 electronic resource (112 pages)

Source: Dissertations Abstracts International, Volume: 85-02, Section: B.

The motivation of this dissertation was to develop methods to analyze optical binding as a self-organization tool for colloidal matter. Since the initial experimental validation of optical binding achieved by [1], the application of interest was to eventually realize the self-organization of many-particle systems using light. The original findings by Burns, Fournier and Golovchenko, which were inspired by the experimental work of [2] on optical forces and theoretical work of [3] on intermolecular radiation forces, illustrated unique features of optical binding. One major finding was that the interaction featured multiple stable points between two interacting dielectric spheres. The second finding was that the stable displacements corresponded to the wavelength of the applied field [1]. With these two features, a new force was introduced which could be applied externally to colloidal systems. This interaction could be tuned to set the strength and inter-particle distances. The current work presented is an extension of this primary work onto many-body systems. Specifically, we aimed to provide a pathway towards determining how one might practically design self-organization behaviors using optical binding forces.There have been numerous studies in the past focused on using optical binding for the self-organization of multiple particles. Partially because of its wide applicability and high specificity, it remains difficult to piece together a coherent link between the various optical binding experiments achieved in the past. For example, it is common to describe distinct optical binding setups based on relative particle size, orientation of the beam axis, beam-type, and damping conditions of the surrounding medium to name a few. In some cases, experiments have described vast differences in behaviors by subtle changes in particle size. Likewise, in this dissertation, I describe how subtle changes in relative refractive index can also strongly alter the behavior in optically bound systems. While these examples illustrate tunability, which is generally ideal for designing self-organized systems, the non-linearity of optical binding makes it extremely difficult to predict.Some of the primary behaviors that are addressed in this dissertation include: non-conservative, non-pairwise, and non-reciprocal interactions and how they interface with the stability and activity of the system. Non-conservative forces are generally present in optical forces. It is common even to separate the conservative gradient and non-conservative scattering force in the discussion of optically induced forces. In application, optical tweezers and optical traps in fact utilize a fine tuned balance of these two forces. Because optical binding is ultimately a second-order effect derived from these optical forces, non-conservative optical binding is expected. However, because optical scattering and absorption is dependent on polarizability, a complex variable which is tied to a number of physical properties of the material, the field, and the surrounding medium, the strength and relevance of non-conservative effects can range. For instance, conservative gradient forces dominate for particles that are relatively small compared to the field wavelength. In this dissertation, I discuss these effects with respect to the complex part of the polarizability. For application of optical binding on large colloidal systems, non-conservative forces are important. [8] showed, for instance, that the strong presence of non-conservative forces can play a role in stability of large optically bound systems. This is an extremely important detail because if the goal is to generate a large ordered structure, you would not want the emergence of instabilities. On the other-hand, instabilities could be desirable if you are indeed interested in active material properties. In either case, it would be beneficial to know exactly when non-conservative forces will disrupt stability.Less studied are the presence non-pairwise forces in optical binding systems. Non-pairwise forces in this system can ultimately arise from multiple scattering effects. While multiple scattering and non-pairwise interactions are not new to discussions of optical scattering, they are usually discussed at the molecular sub-particle scale. In this dissertation work, I discuss the potential effect of N-body forces between particles in close proximity. In the past, these effects have been generally ignored. For small particles, it is found that non-pairwise forces are negligible. There aren't however clear guidelines for when this remains true for larger particles. In this dissertation, I present numerical approaches which help us discern the strength of non-pairwise contributions for a number of configurations. We studied for instance the dependence on particle size along with alternative parameters such as relative refractive index and orientation. Furthermore, I present experimental evidence of collective action.Finally, I address the presence of non-reciprocity in optical binding. Nonreciprocal interactions are closely related to non-conservative interactions but are more specific to multiple species in which one species exerts a force on another without experiencing the equal and opposite effect. We have yet to observe optical binding experiments which include multiple species of scatterers; however, we do explore the presence of non-reciprocal forces in single species systems. I address these non-reciprocal forces with numerical approaches. The numerical studies are inspired by our experimental work which shows the formation of small semi-stable clusters from a system of identical spheres. In other words, we found an emergence of a two-species system from a single species system. More so, the findings strongly suggest that the interactions can be non-reciprocal. These results and their implications are discussed in Chapter 2.As much as this dissertation attempts to answer about optical binding, it is also a description of new approaches of studying optical binding itself. Generating self-organization with optical binding can require extremely strong optical fields. Even more difficult is the integration of imaging optics which can accommodate a high powered laser. For the reader, I include the experimental techniques that worked best along with a few alternative methods. The hope is that these methods provide an easier pathway towards the study of optical binding or other light matter phenomena. For instance, in Chapter 2 you will find the description of a custom built microscope system which allowed us to capture 3-dimensional images of a sample subjected to a high powered laser source while I also describe an entirely alternative system which geometry offers more control of the field propagation angle.In Chapter 3, I present our work in integrating optical binding forces into a molecular dynamics simulation framework. While various simulations of optical binding forces have been made by researchers in the past, the most relevant to this dissertation being the work in [10], our goals were guided by finding approaches which can handle a larger assortment of particles and be easily integrated to include the effects of Brownian motion and additional forces. To that end, this dissertation required the development of several scattering simulations. The first is a scattering code based mainly on the Coupled Dipole Method (CDM), also known as the Discrete Dipole Approximation (DDA). While work remains to be done to increase computational speed for larger simulations, I share results of small scale simulations which include thermal fluctuations and additional interactions. Unlike Mie scattering theory methods, CDM is generally easier to extend for many particles that may be non-spherical or non-homogeneous.The second scattering code presented briefly in this dissertation utilizes the method of fundamental solutions (MFS) to obtain scattering results. The major difference between CDM and MFS is that CDM requires that an object be approximated by scattering bodies that fill the volume whereas MFS can be used with scattering bodies that fill on the surface area saving computational cost. The computational development of this method was prepared by collaborator Arnold D. Kim. The method was developed specifically for acoustic binding, with which Nicholas St.

English

ISBN: 9798380091541Subjects--Topical Terms:

543314
Materials science.
Subjects--Index Terms:

Colloidal

Active Colloidal Self-Assembly With Optical Binding Forces /
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245 1 0 $a Active Colloidal Self-Assembly With Optical Binding Forces / $c Dominique Davenport.
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520 $a The motivation of this dissertation was to develop methods to analyze optical binding as a self-organization tool for colloidal matter. Since the initial experimental validation of optical binding achieved by [1], the application of interest was to eventually realize the self-organization of many-particle systems using light. The original findings by Burns, Fournier and Golovchenko, which were inspired by the experimental work of [2] on optical forces and theoretical work of [3] on intermolecular radiation forces, illustrated unique features of optical binding. One major finding was that the interaction featured multiple stable points between two interacting dielectric spheres. The second finding was that the stable displacements corresponded to the wavelength of the applied field [1]. With these two features, a new force was introduced which could be applied externally to colloidal systems. This interaction could be tuned to set the strength and inter-particle distances. The current work presented is an extension of this primary work onto many-body systems. Specifically, we aimed to provide a pathway towards determining how one might practically design self-organization behaviors using optical binding forces.There have been numerous studies in the past focused on using optical binding for the self-organization of multiple particles. Partially because of its wide applicability and high specificity, it remains difficult to piece together a coherent link between the various optical binding experiments achieved in the past. For example, it is common to describe distinct optical binding setups based on relative particle size, orientation of the beam axis, beam-type, and damping conditions of the surrounding medium to name a few. In some cases, experiments have described vast differences in behaviors by subtle changes in particle size. Likewise, in this dissertation, I describe how subtle changes in relative refractive index can also strongly alter the behavior in optically bound systems. While these examples illustrate tunability, which is generally ideal for designing self-organized systems, the non-linearity of optical binding makes it extremely difficult to predict.Some of the primary behaviors that are addressed in this dissertation include: non-conservative, non-pairwise, and non-reciprocal interactions and how they interface with the stability and activity of the system. Non-conservative forces are generally present in optical forces. It is common even to separate the conservative gradient and non-conservative scattering force in the discussion of optically induced forces. In application, optical tweezers and optical traps in fact utilize a fine tuned balance of these two forces. Because optical binding is ultimately a second-order effect derived from these optical forces, non-conservative optical binding is expected. However, because optical scattering and absorption is dependent on polarizability, a complex variable which is tied to a number of physical properties of the material, the field, and the surrounding medium, the strength and relevance of non-conservative effects can range. For instance, conservative gradient forces dominate for particles that are relatively small compared to the field wavelength. In this dissertation, I discuss these effects with respect to the complex part of the polarizability. For application of optical binding on large colloidal systems, non-conservative forces are important. [8] showed, for instance, that the strong presence of non-conservative forces can play a role in stability of large optically bound systems. This is an extremely important detail because if the goal is to generate a large ordered structure, you would not want the emergence of instabilities. On the other-hand, instabilities could be desirable if you are indeed interested in active material properties. In either case, it would be beneficial to know exactly when non-conservative forces will disrupt stability.Less studied are the presence non-pairwise forces in optical binding systems. Non-pairwise forces in this system can ultimately arise from multiple scattering effects. While multiple scattering and non-pairwise interactions are not new to discussions of optical scattering, they are usually discussed at the molecular sub-particle scale. In this dissertation work, I discuss the potential effect of N-body forces between particles in close proximity. In the past, these effects have been generally ignored. For small particles, it is found that non-pairwise forces are negligible. There aren't however clear guidelines for when this remains true for larger particles. In this dissertation, I present numerical approaches which help us discern the strength of non-pairwise contributions for a number of configurations. We studied for instance the dependence on particle size along with alternative parameters such as relative refractive index and orientation. Furthermore, I present experimental evidence of collective action.Finally, I address the presence of non-reciprocity in optical binding. Nonreciprocal interactions are closely related to non-conservative interactions but are more specific to multiple species in which one species exerts a force on another without experiencing the equal and opposite effect. We have yet to observe optical binding experiments which include multiple species of scatterers; however, we do explore the presence of non-reciprocal forces in single species systems. I address these non-reciprocal forces with numerical approaches. The numerical studies are inspired by our experimental work which shows the formation of small semi-stable clusters from a system of identical spheres. In other words, we found an emergence of a two-species system from a single species system. More so, the findings strongly suggest that the interactions can be non-reciprocal. These results and their implications are discussed in Chapter 2.As much as this dissertation attempts to answer about optical binding, it is also a description of new approaches of studying optical binding itself. Generating self-organization with optical binding can require extremely strong optical fields. Even more difficult is the integration of imaging optics which can accommodate a high powered laser. For the reader, I include the experimental techniques that worked best along with a few alternative methods. The hope is that these methods provide an easier pathway towards the study of optical binding or other light matter phenomena. For instance, in Chapter 2 you will find the description of a custom built microscope system which allowed us to capture 3-dimensional images of a sample subjected to a high powered laser source while I also describe an entirely alternative system which geometry offers more control of the field propagation angle.In Chapter 3, I present our work in integrating optical binding forces into a molecular dynamics simulation framework. While various simulations of optical binding forces have been made by researchers in the past, the most relevant to this dissertation being the work in [10], our goals were guided by finding approaches which can handle a larger assortment of particles and be easily integrated to include the effects of Brownian motion and additional forces. To that end, this dissertation required the development of several scattering simulations. The first is a scattering code based mainly on the Coupled Dipole Method (CDM), also known as the Discrete Dipole Approximation (DDA). While work remains to be done to increase computational speed for larger simulations, I share results of small scale simulations which include thermal fluctuations and additional interactions. Unlike Mie scattering theory methods, CDM is generally easier to extend for many particles that may be non-spherical or non-homogeneous.The second scattering code presented briefly in this dissertation utilizes the method of fundamental solutions (MFS) to obtain scattering results. The major difference between CDM and MFS is that CDM requires that an object be approximated by scattering bodies that fill the volume whereas MFS can be used with scattering bodies that fill on the surface area saving computational cost. The computational development of this method was prepared by collaborator Arnold D. Kim. The method was developed specifically for acoustic binding, with which Nicholas St.
520 $a Clair explored the dynamics of particle clusters driven by acoustic field scattering interactions. This dissertation explores those results in terms of optical fields, particularly how these systems can be approached numerically in a similar manner.
546 $a English
590 $a School code: 1660
650 4 $a Materials science. $3 543314
650 4 $a Condensed matter physics. $3 3173567
650 4 $a Particle physics. $3 3433269
653 $a Colloidal
653 $a Optical binding
653 $a Optical forces
653 $a Self-assembly
653 $a Soft-matter
690 $a 0794
690 $a 0798
690 $a 0611
710 2 $a University of California, Merced. $b Physics. $e degree granting institution. $3 3823863
720 1 $a Kleckner, Dustin $e degree supervisor.
720 1 $a Hirst, Linda $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 85-02B.
790 $a 1660
791 $a Ph.D.
792 $a 2022
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