title: Simultaneous measurement of orientational and spectral dynamics of single molecules in nanostructured host-guest materials.
abstract: Nanostructured host-guest materials are important for various applications in nanoscience, and therefore, a thorough understanding of the dynamics of the guest molecules within the host matrix is needed. To this aim we used single-molecule fluorescence techniques to simultaneously examine the spectral and the orientational behavior of single molecules in nanostructured porous host materials. Two types of host-guest systems have been investigated. First, oxazine-1 dye molecules were fixed rigidly in the channels of microporous AlPO4-5 crystals. Second, it was shown that terrylenediimide (TDI) dye molecules move in the mesoporous network of an uncalcined M41S thin film. In the first sample both spectral fluctuations ( approximately 5 nm) and rare spectral jumps (>10 nm) of the emission maximum were observed. However, the orientation of the emission dipole of the dye molecules remained constant. In contrast, the second system showed orientational dynamics as well as substantially more spectral dynamics. In this system the molecules were found to move between different regions in the host. The typical motion of the TDI molecules in the pores of M41S was not continuous but characterized by jumps between specific sites. Moreover, the spectral and orientational dynamics were correlated and arose directly from the different environments that were being explored by the mobile molecule.
authors.affiliation: Department of Chemistry und Biochemistry, Nanosystems Initiative Munich, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, D-81377 München, Germany.
authors.forename: Christophe
authors.initials: C
authors.lastname: Jung
authors.forename: Christian
authors.initials: C
authors.lastname: Hellriegel
authors.forename: Barbara
authors.initials: B
authors.lastname: Platschek
authors.forename: Dieter
authors.initials: D
authors.lastname: Wöhrle
authors.forename: Thomas
authors.initials: T
authors.lastname: Bein
authors.forename: Jens
authors.initials: J
authors.lastname: Michaelis
authors.forename: Christoph
authors.initials: C
authors.lastname: Bräuchle