The use of holographic optical tweezing in the spectroscopic analysis of micron-sized compartments

Optical tweezers is an exciting and unique scientific instrument, which uses a highly focused laser to isolate and manipulate micron-sized dielectric particles in three-dimensions. The work undertaken in this thesis is divided into two themes. Firstly, it describes the design, construction and adaptation of a holographic optical tweezer (HOT) capable of multi-spectroscopy experiments. Secondly, the holographic optical tweezer is used to isolate and spectroscopically investigate microparticles of different colloidal systems. Chapter 1 provides an introduction to the field of optical manipulation from the first observation by Ashkin to the present day where novel beam shaping technology is being used to simultaneously manipulate multiple particles. It also covers an introduction to the three colloidal systems which have been investigated using the HOT. Chapter 2 outlines the components of a generic optical tweezer and describes in detail the one used in the current study. Chapter 3 covers the application of the HOT on aqueous droplets suspended in air. The binary coalescence and bistable axial trapping positions of aqueous aerosols were investigated using elastically-scattered laser light from the trapped droplet. This is a new technique which was developed by the Optical Tweezers group at the University of Leicester. The work described in chapter 4 the HOT adapted to perform resonance Raman measurements and used to investigate the catalytic cycle of membrane-bound human cytochrome P450 incorporated into a vesicle. Chapter 5 lays down the preliminary work in generating a stable reverse emulsion of water-in-fluorocarbon. The emulsion is being developed as a micro-reactor vessel to monitor biological processes in the near future.