In the same way as mesoscopic confinements give rise to a rich dynamic behavior of confined fluids, mesoscopic organization of matter and interactions developing on mesoscales may lead to similar phenomena in soft-matter systems. Examples of such situations include the occurrence of sub-diffusion in crowded environments, cage effects in colloids, and complex structure-dynamics relationships in liquid crystals. We use the pulsed field gradient technique of NMR to probe translational dynamics in complex soft-matter. One of our particular goals is developing a unified experimental and theoretical concept for comparing the results of single-particle tracing and ensemble-based techniques. An important example we may refer to in this respect is the first experimental proof of the ergodic theorem by measuring the diffusivity of guest molecules inside a nano-structured porous glass. The data obtained through the direct observation of dye molecule diffusion by single-molecule tracking experiments, i.e. the time-average, was found to be in perfect agreement with the ensemble value obtained in NMR experiments.    

  1. A Shakhov, R Valiullin and J Kärger. Tracing Molecular Propagation in Dextran Solutions by Pulsed Field Gradient NMR. J. Phys. Chem. Lett. 3:1854-1857, 2012. BibTeX

    @article{Shakhov2012,
    	author = "Shakhov, A. and Valiullin, R. and Kärger, J.",
    	title = "Tracing Molecular Propagation in Dextran Solutions by Pulsed Field Gradient NMR",
    	journal = "J. Phys. Chem. Lett.",
    	volume = 3,
    	pages = "1854-1857",
    	year = 2012
    }
    
  2. F Feil, S Naumov, J Michaelis, R Valiullin, D Enke, J Kärger and C Bräuchle. Single-Particle and Ensemble Diffusivities—Test of Ergodicity. Angew. Chem. 124:1178-1181, 2012. BibTeX

    @article{Feil2012,
    	author = "Feil, F. and Naumov, S. and Michaelis, J. and Valiullin, R. and Enke, D. and Kärger, J. and Bräuchle, C.",
    	title = "Single-Particle and Ensemble Diffusivities—Test of Ergodicity",
    	journal = "Angew. Chem.",
    	volume = 124,
    	pages = "1178-1181",
    	year = 2012
    }
    
  3. J R Sangoro, C Iacob, S Naumov, R Valiullin, H Rexhausen, J Hunger, R Buchner, V Strehmel, J Kärger and F Kremer. Diffusion in ionic liquids: the interplay between molecular structure and dynamics. Soft Matter 7:1678-1681, 2011. BibTeX

    @article{Sangoro2011,
    	author = "Sangoro, J. R. and Iacob, C. and Naumov, S. and Valiullin, R. and Rexhausen, H. and Hunger, J. and Buchner, R. and Strehmel, V. and Kärger, J. and Kremer, F.",
    	title = "Diffusion in ionic liquids: the interplay between molecular structure and dynamics",
    	journal = "Soft Matter",
    	volume = 7,
    	pages = "1678-1681",
    	year = 2011
    }
    
  4. M G Mazza, M Greschek, R Valiullin, J Kärger and M Schoen. Entropy-driven enhanced self-diffusion in confined reentrant supernematics. Phys. Rev. Lett. 105:227802, 2010. BibTeX

    @article{Mazza2010,
    	author = "Mazza, M. G. and Greschek, M. and Valiullin, R. and Kärger, J. and Schoen, M.",
    	title = "Entropy-driven enhanced self-diffusion in confined reentrant supernematics",
    	journal = "Phys. Rev. Lett.",
    	volume = 105,
    	pages = 227802,
    	year = 2010
    }
    

 

 

 

 
   
© Rustem Valiullin, 2006-2013