Orientation of molecular probes in latent ion tracks

By using polarized fluorescence spectroscopy, the orientation properties of special molecular probes deposited in the ion tracks were investigated. Fo ils of poly(ethylene terephthalate) (PET) were used as a matrix for the ion tracks wherein fluorescence probes such as aminostyryl-derivatives can be incorporated using a suitable solvent e.g. N,N'-dimethylformamide (DMF) as transport medium. The diffusion of a small amount of probes into the virgin material and the high sensitivity of fluorescence methods allows the compa rison of probe properties in ion tracks with that in virgin material. By me ans of polarized fluorescence spectroscopy it is shown that deposited molec ular probes with a high aspect ratio have a preferential orientation parall el to the ion track axis. The orientation of the molecular probes indicates that molecules can be aligned in ion tracks without inter-diffusion into t he track surrounding material. The breakdown of the orientation at high are al doses can be correlated with the increasing multiple overlapping of the ion tracks.