• Selected Publications

Dr. Tobias Vossmeyer

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Scientific staff

address:
Universität Hamburg
Institut für Physikalische Chemie
Grindelallee 117
D-20146 Hamburg
Germany

room:
349a

telephone:
040/42838-7069

e-mail:
tobias.vossmeyer  (at) chemie.uni-hamburg.de

Tobias Vossmeyer studied chemistry at the Philipps-Universität Marburg, Germany, and received his Diploma in 1992. Thereafter, he worked as a Ph.D. student at the Hahn-Meitner Institute, Berlin, where he investigated the formation of superlattice assemblies from semiconductor nanoparticles. He received his Ph.D. in 1995 from the Technical University Berlin. After working on the lithographically controlled deposition of nanoparticle patterns at the University of California at Los Angeles (UCLA) he started a research position at Sony’s Stuttgart Technology Center in 1998. Until 2007 he worked as group leader at Sony’s Materials Science Laboratories where his work focused on the development of novel nanostructured materials for applications as chemical sensors. In 2007 he started a faculty scientist position at the Institut für Physikalische Chemie (IPhCh) of the University of Hamburg. His current research interests are functional nanostructured materials and devices, self-assembly, molecular recognition and design of interfaces, and chemical sensors.

Selected Publications

Natalia Olichwer, Elisabeth W. Leib, Annelie H. Halfar, Alexey Petrov and Tobias Vossmeyer:

Cross-Linked Gold Nanoparticles on Polyethylene: Resistive Responses to Tensile Strain and Vapors

In this study coatings of cross-linked gold nanoparticles (AuNPs) on flexible polyethylene (PE) substrates were prepared via layer-by-layer deposition and their application as strain gauges and chemiresistors was investigated. Special emphasis was placed on characterizing the influence of strain on the chemiresistive responses. The coatings were deposited using amine stabilized AuNPs (4 and 9 nm diameter) and 1,9-nonanedithiol (NDT) or pentaerythritol tetrakis(3-mercaptopropionate) (PTM) as cross-linkers. In order to prepare films with homogeneous optical appearance, it was necessary to treat the substrates with oxygen plasma directly before film assembly. SEM images revealed film thicknesses between ~60 and ~90 nm and porous nanoscale morphology. All films showed ohmic IV-characteristics with conductivities ranging from 10^-4 to 10^‑2 Ohm^-1cm^-1, depending on the structure of the linker and the nanoparticle size. When up to 3% strain was induced their resistance increased linearly and reversibly (gauge factors: ~20). A comparative SEM investigation indicated that the stress induced formation and extension of nanocracks are important components of the signal transduction mechanism. Further, all films responded with a reversible increase in resistance when dosed with toluene, 4-methyl-2-pentanone, 1-propanol or water vapor (concentrations: 50 - 10 000 ppm). Films deposited onto high density PE substrates showed much faster response-recovery dynamics than films deposited onto low density PE. The chemical selectivity of the coatings was controlled by the chemical nature of the cross-linkers, with the highest sensitivities (~10^-5 ppm^-1) measured with analytes of matching solubility. The response isotherms of all film/vapor pairs could be fitted using a Langmuir-Henry model suggesting selective and bulk sorption. Under tensile stress (1% strain) all chemiresistors showed a reversible increase in their response amplitudes (~30%), regardless of the analytes’ permittivity. Taking into consideration the thermally activated tunneling model for charge transport, this behavior was assigned to stress induced formation of nanocracks, which enhance the films’ ability to swell in lateral directions during analyte sorption.

ACS App. Mater. Interfaces 2012, 4, 6151 (DOI: 10.1021/am301780b)

Hendrik Schlicke, Jan H. Schröder, Martin Trebbin, Alexey Petrov, Michael Ijeh, Horst Weller, and Tobias Vossmeyer:

Freestanding films of crosslinked gold nanoparticles prepared via layer-by-layer spin-coating

A new, extremely efficient method for the fabrication of films comprised of gold-nanoparticles (GNPs) crosslinked by organic dithiols is presented. The method is based on layer-by-layer spin-coating of both components, GNPs and crosslinker, and enables the deposition of films with several tens of nanometers in thickness within a few minutes. X-ray diffraction and conductance measurements reveal the concentration of the crosslinker solution being critical to adjust properly in order to prevent destabili­zation and coalescence of particles. UV/vis spectroscopy, atomic force microscopy, and conductivity measurements indicate that films prepared via layer-by-layer spin-coating are of comparable quality as coatings prepared via laborious layer-by-layer self-assembly using immersion baths. Because spin-coated films are not bound chemically to the substrate they can be lifted-off by alkaline underetching and transferred onto 3d-electrodes to produce electrically addressable, freely suspended films. Comparative measurements of sheet resistances indicate that the transfer process does not compro­mise the film quality.  

 Nanotechnology 2011, 22, 305303 (DOI:10.1088/0957-4484/22/30/305303 )

  

Tobias Vossmeyer, Carsten Stolte, Michael Ijeh, Andreas Kornowski, Horst Weller:

 Networked Gold Nanoparticle Coatings on Polyethylene: Charge Transport and Strain Sensitivity

Flexible polyethylene substrates are coated with networked gold nanoparticles via layer-by-layer deposition. The strain sensitive charge transport combined with the mecha­nical robustness of the coatings establishes a base for their potential ap­plication as resistive strain sensors.

 Adv. Funct. Mater. 2008, 18, 1611 (DOI: 10.1002/adfm.200701509)

 
 

Nanoparticles, Nanofibers, Chemical Sensors

N. Krasteva, Y. Fogel, R. E. Bauer, K. Müllen, Y. Joseph, N. Matsuzawa, A. Yasuda, T. Vossmeyer:
Vapor Sorption and Electrical Response of Au-Nanoparticle- Dendrimer Composites,
Adv. Funct. Mater. 2007, 17, 881 (online: 2 Mar 2007)

I. Besnard, U.Schlecht, M. Burghard, A. Yasuda, T. Vossmeyer:
V2O5-nanofibres: Novel gas sensors with extremely high sensitivity to amines,
Sens. Actuators B 2005, 106, 730

Y. Joseph, B. Guse, A. Yasuda, T. Vossmeyer:
Chemiresistor coatings from Pt- and Au-nanoparticle/nonandithiol films: Sensitivity to gases and solvent vapors,
Sens. Actuators B 2005, 98, 188

J. M. Wessels, H.-G. Nothofer, W. E. Ford, F. von Wrochem, F. Scholz, T. Vossmeyer, A. Schroeter, H. Weller, A. Yasuda:
Optical and electrical properties of 3-dimensional interlinked Au-nanoparticle assemblies,
J. Am. Chem. Soc.  2004, 126, 3349

U. Schlecht, B. Guse, I. Raible, T. Vossmeyer, M. Burghard:
A direct synthetic approach to vanadium pentoxide nanofibres modified with silver-nanoparticles,
Chem. Commun. 2004, 2184

Y. Joseph, N. Krasteva, I. Besnard, B. Guse, M. Rosenberger, U. Wild, A. Knop-Gericke, R. Schlögl, A. Yasuda, T. Vossmeyer:
Gold-nanoparticle/organic linker films: self-assembly, electronic and structural characterisation, composition and vapour sensitivity,
Faraday Discuss. 2004, 125, 77

N. Krasteva, R. Krustev, A. Yasuda, T. Vossmeyer:
Vapour sorption in self-assembled gold nanoparticle/dendrimer films studied by specular neutron reflectometry,
Langmuir 2003, 19, 7754

Joseph, I. Besnard, M. Rosenberger, B. Guse, H.-G. Nothofer, J. M. Wessels, U. Wild, A. Knop-Gericke, D. Su, R. Schlögl, A. Yasuda, T. Vossmeyer:
Self-Assembled gold-nanoparticle/alkanedithiol films: Preparation, electron microscopy, XPS-analysis, charge transport, and vapor-sensing properties,
J. Phys. Chem. B 2003, 107, 7406

N. Krasteva, B. Guse, I. Besnard, A. Yasuda, T. Vossmeyer:
Gold nanoparticle/PPI-dendrimer based chemiresistors: Vapor-sensing properties as a function of the dendrimer size,
Sens. Actuators B 2003, 92, 137

N. Krasteva, I. Besnard, B. Guse, R.E. Bauer, K. Müllen, A. Yasuda, T. Vossmeyer:
Self-assembled gold nanoparticle/dendrimer composite films for vapor sensing applications,
Nano Lett. 2002, 2, 551

T. Vossmeyer, B. Guse, I. Besnard, R.E. Bauer, K. Müllen, A. Yasuda:
Gold nanoparticle/polyphenylen dendrimer composite films: Preparation and vapor-sensing properties,
Adv. Mater. 2002, 14, 238

T. Vossmeyer, L. Katsikas, M. Giersig, I. G. Popovic, K. Diesner, A. Chemseddine, A. Eychmüller, H. Weller:
CdS Nanoclusters: Synthesis, characterization, size dependent oscillator strength, temperature shift of the excitonic transition energy, and reversible absorbance shift,
J. Phys. Chem. 1994, 98, 7665

Superlattices of Nanocrystals

T. Vossmeyer, S.-W. Chung, W. M. Gelbart, J. R. Heath: „Surprising superstructures: Rings“,
Adv. Mater. 1998, 10, 351

C. P. Collier, T. Vossmeyer, J. R. Heath:
Quantum dot superlattices,
Ann. Rev. Phys. Chem. 1998, 49, 371

T. Vossmeyer, G. Reck, L. Katsikas, E. T. K. Haupt, B. Schulz, H. Weller:
A double-diamond superlattice built up of Cd17S4(SCH2CH2OH)26 clusters,
Science 1995, 267, 1476

T. Vossmeyer, G. Reck, B. Schulz, L. Katsikas, H. Weller:
A double-layer superlattice structure built up of Cd32S14(SCH2CH(OH)CH3)36.4H2O clusters,
J. Am. Chem. Soc. 1995, 117, 12881

T. Vossmeyer, L. Katsikas, M. Giersig, I. G. Popovic, K. Diesner, A. Chemseddine, A. Eychmüller, H. Weller:
CdS Nanoclusters: Synthesis, characterization, size dependent oscillator strength, temperature shift of the excitonic transition energy, and reversible absorbance shift,
J. Phys. Chem. 1995, 98, 7665

Lithographically controlled deposition of Nanoparticle Assemblies

O. Harnack, I. Besnard, A. Yasuda, T. Vossmeyer:
Lithographic patterning of layer-by-layer self-assembled nanostructures using a water-soluble mask,
Appl. Phys. Lett. 2005, 86, 034108

T. Vossmeyer, S. Jia, E. DeIonno, M. R. Diehl, S.-H. Kim, X. Peng, A. P. Alivisatos, J. R. Heath: Combinatorial approaches toward patterning nanocrystals,
J. Appl. Phys. 1998, 84, 3664

T. Vossmeyer, E. DeIonno, J. R. Heath:
Light directed assembly of nanoparticles,
Angew. Chem. 1997, 109, 1123, Angew. Chem. Int. Ed. Engl. 1997, 36, 1080

J. R. Heath, T. Vossmeyer, E. DeIonno, G. Markovich:
Parallel processing of nanocrystal colloids: Light directed assembly and simple devices,
Nanostructured Materials - Clusters, Composites, and Thin Films, ACS Symposium Series 679, ed. by V. M. Shalaev and M. Moskovits, Seite 1 (1997)