Investigations in the use of the optical trap in the regulation of optical emission characteristics in polymer systems

The effect of focused visible laser radiation on micron diameter particles of polystyrene is investigated. The optical trap formed by highly focused laser radiation allows the particle to be immobilized in solution for analysis. As a result of the high intensity radiation and the presence of visible light absorbing species in the particle, a region of conjugation is formed in the polystyrene backbone. This conjugation results in broad fluorescence emission from the polystyrene particle. The photochemical reaction responsible for conjugation is characterized by temporal and emission characteristics. These variables are shown to be dependent on laser power, excitation wavelength, particle size, suspending solvent, and in the case of mixed composition polymer particles, the percent of polystyrene in the particle. Pure polystyrene particles ranging in size from 500nm to over 15;The results presented in this thesis demonstrate that polystyrene can be photochemically modified in a visible optical trap to produce a fluorescent species. The emission characteristics are influenced by the size of the particle, the trap power and wavelength, and the suspending solvent. A method for the detection of polystyrene in mixed polymer particles is presented as well as a method for the rapid production of the conjugated polystyrene species by low intensity radiation in the presence of silver ion. In addition it is possible to determine the weight percentage of polystyrene in individual mixed-polymer particles.