Time, space and spectrally resolved photochemistry from ensembles to single molecules

Coupling of photophysical and photochemical techniques to microscopy eventu ally assisted by manipulating techniques, such as laser trapping, has facil itated obtaining information on heterogeneous organic and bio-organic syste ms by mapping their optical and excited state properties. Scanning confocal microscopy, eventually of laser trapped ensembles, coupled to fluorescence decay analysis and imaging, scanning plate confocal and scanning near fiel d optical microscopy provide combined spectral and spatial resolution down to a few tenths of nanometers. An even better resolution can be achieved us ing scanning tunneling microscopy. In this contribution a number of organic and macromolecular systems are discussed first in solution and in a next s tep assembled either in a trap or at a surface. The techniques are illustra ted and their limits assessed using latex particles labeled with fluorophor es. Time resolved spectroscopy in solution allows the evaluation of migrati on of the excited state and the collapse of the arms in a dendritic structu re. These and other macromolecular structures can be trapped and the obtain ed assembly visualized and analyzed. Deposition by self-assembly provides t he possibility using scanning near field optical microscopy to investigate the excited state properties of ordered arrays. By dilution in a polymer fi lm of dendritic structures single particle, single chromophore and single m olecule spectroscopy becomes accessible. Scanning tunneling microscopy is s uccessfully applied to illustrate the visualization and manipulation of str uctures with subnanometer resolution and the study of their properties incl uding stimulus by light induced transformations.