The potential of a novel silver-silver oxide system for optical data storage with fluorescent readout has been discovered and developed. These properties arise from photolytic production of highly fluorescent single Agn molecules (n = 2-6 atoms) from silver oxide. Optical experiments with a 514.5nm Ar+ laser and a 100W Hg lamp allow determination of single Agn nanocluster absorption cross- sections ((sigma) = 8 x 10-15 cm2) and saturation intensities (Isat = 200 W/cm2 at 514.5 nm). Single molecule fluorescence experiments have elucidated the dynamics of AgO photoactivation and subsequent Agn nanocluster emission. Additionally, excitation, wavelength and intensity dependent dynamics are investigated. Results clearly show dependence on wavelength and intensity in Agn nanocluster creation and destruction.
The development of fluorescence spectroscopy and imaging on the single molecule level has provided a new method to investigate various phenomena in condensed phase at liquid helium and room temperature unobscured by ensemble averaging. Single molecule spectroscopy allows studying the photophysical behavior of chromophores as well as using those chromophores as a probe for their local environment. A crucial problem that has to be overcome for single molecule studies in the liquid phase is Brownian motion: only partially or completely immobilized molecules allow extended observation. Here we report on the use of water-based polyacrylamide gels as a promising medium for single molecule investigations at room temperature with wide-field total internal reflection microscopy. The gel framework dramatically reduced Brownian motion of small fluorescent dye molecules. Observation of the diffusion of these molecules served as a probe for the inner structure of the gels. Furthermore these water-based gels form a useful medium for single molecule studies of biological systems in vitro.
Conference Committee Involvement (1)
Physical Chemistry of Interfaces and Nanomaterials II
6 August 2003 | San Diego, California, United States
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