| The study of spatial and temporal fluctuations ties together the disparate topics covered here, although this work is as much about the tools we use to study these fluctuations.; Near-field microscopy uses the nature of light transmitted through a sub-wavelength metal aperture to image spatial fluctuations beyond the resolution limits of conventional far-field microscopy. We present a novel near-field scanning optical microscope and use it to image dynamics of single fluorescent molecules.; Liquid polymer based fiber-optic ion sensors contain fluorescent chromoionophores that photobleach during use. We show that in nanosensors, diffusional replenishing of these fluorophores from the bulk of the unilluminated film extends the life of these sensors enormously. Utilizing the natural spatial and temporal fluctuations in the indicator populations and the ultra-small sensor volume, the sensors can be used for short periods interspersed by rest intervals allowing recovery.; In diffusion-limited chemical reaction kinetics, natural or induced spatial variations in reactant distributions lead to temporally anomalous reaction rates when compared with the classical ("textbook"), mean-field rate laws. In the case of a trapping reaction, A+T → T, we have shown experimentally, using localized photobleaching of fluorescein in quasi-1D and 2D chambers, dimension-dependent rate behaviors predicted analytically and by computer simulations, and destroyed by stirring.; In the case of A+B → 0 reactions, naturally inefficient diffusional transport creates a "memory" of the initial reactant distribution, which leads to segregated pockets of reactants with intervening gaps, and thus, to anomalously slow reaction rates. We study a case in which one reactant is randomly distributed and the other has a "speckled" distribution created by a UV laser pulse. This reaction exhibits one rate regime due to the speckles, and another rooted in reactant self-segregation, exhibiting the non-classical three-dimensional Zeldovich power law reaction progress.; Finally, the fluctuations within simulated, diffusion-limited reactions are illuminated using a wavelet based analysis. This tool is ideally suited to the scaling nature of these reactions in both space and time, and shows how the reactant fluctuations persist and grow, leading to non-classical behaviors. |
