Nanotechnology

Microscopy

All kinds of microscopy are important tools for studying the topology of samples. Whereas the resolution of conventional optical microscopy, which has been used for more than 500 years, is restricted by the wavelength of light in the visible range, atomic resolution can be achieved with the scanning electron, the transmission electron microscope (TEM) and with the scanning force microscopy.

In our group we have two scanning electron microscopes (SEM), a transmission electron microscope (TEM) and a scanning probe microscope (SPM). The latter one allows measurements in the scanning force (AFM) as well as in the magnetic force microscopy (MFM) mode.

In a transmission electron microscope (TEM), the sample is continuously illuminated by a widened electron beam. The transmitted electrons are guided onto a fluorescent screen by an electron optical system to form an image. By varying the lens currents of the electromagnetic lens it is possible to adjust its focal length, and thus to choose a magnification.

The TEM available in our institute, a Philips CM12, is capable of performing bright field imaging and transmission electron diffraction. The maximum acceleration voltage of the TEM is 120 keV, which leads to a minimum de Broglie wavelength for electron diffraction of 3.53e-12 m. It is equipped with a LaB₆ cathode, the maximum magnification ranges up to 600000x.

The samples can be prepared on two different types of substrates. First, amorphous carbon films, supported by copper grids are available. These carbon films feature a very low background in diffraction experiments, because of the low atomic number and their low layer thickness. Second, there are silicon nitride membranes supported by silicon frames.

Transmissionselektronenmikroskop Philips CM12 — Fig. 1: TEM Philips CM12.

Eisenoxidnanopartikel TEM — Fig. 2: TEM bright field image of iron oxide magnetic nanoprticles (300000x).

Elektronenbeugung TEM — Fig. 3: Transmission electron diffraction of of iron oxide magnetic nanoprticles in comparison with a simulated diffraction pattern.

Using the TEM it is, for example, possible to directly investigate the morphology, size distribution and crystal structure of nano particles, see figures 2 and 3.

Rastersondenmikroskop — Fig.1: Scanning Probe Microscope

In our group we have two scanning electron microscopes (SEM) and one scanning probe microscope (SPM, Fig. 1). The analogue SEMs are equipped with conventional filament electron sources so that a high resolution can only be achieved by comparably electron energies (> 10 keV). As a consequence samples should be metallic or metallized to prevent them from charging up.

SPM is a relatively new technique. Binning and Rohrer introduced in 1982 the scanning tunneling microscope where the tunnel current between a very sharp metallic tip and the sample is used to get information on the sample morphology. Clearly, the disadvantage of this technique is that samples have to be conducting. Lateron, a variety of SPM techniques has been developed, as e.g. the scanning force microscopy (SFM) which is based on atomic forces between tip and sample and magnetic force microscopy (MFM) where a magnetized tip interacts with the domains of a magnetic sample. In contrast to optical microscopy and SEM, SPM provides a real 3-dimensional image of the sample topography.

In our group we have a SPM built at the Danish company DME. The microscope utilizes a tube piezo scanner, i.e. the probe is scanned across the sample, and allows one to scan across a maximum area of 50 µm x 50 µm. Currently, we have the option to operate the SPM in the contact mode (highest resolution but requires nearly flat surfaces), in the ac mode where the cantilever with the tip oscillates with a frequency of about 170 kHz up and down and the controller uses deviations in oscillation amplitude and phase to reconstruct the surface topography, and Magnetic Force Microscopy (MFM).

Fig 2: 5 µm x 5 µm AC mode scan of SrTiO3 substrate after HF etch and annealing. Unit cell steps are clearly visible. The arrow shows a scew dislocation at the surface of the chrystal lattice

ybco — Fig 3: 1,5µm x 1,5µm DC mode scan of YBa2Cu3O7 thin film

bacillus megaterium — Fig. 4: AFM-Image of Bacillus megaterium

In addition to our studies on thin-films and thin-film structures we plan to investigate biological samples in liquids within the SFB 578.

In addition to the microscopy mode the system allows spectroscopic measurements. Here we concentrate on recording force-distance curves, which provide information e.g. about binding forces between molecules.

MFM

By using a magnetically coated tip on the cantilever the SPM allows one to perform magnetic force microscopical (MFM) measurements.

In a scanning electron microscope (SEM), a focused electron beam scans the sample surface line by line. Simultaneously, the response of the sample, typically the emission of secondary electrons, is recorded. Displaying the measured signal as a function of the illuminated position results in an image of the sample.

We possess three scanning electron microscopes in our institute. The two Philips devices (SEM 505 and SEM 525) are equipped with a common tungsten hairpin filament, and a LaB_6 electron source, respectively. High resolutions can only be achieved, when using higher accelerating voltages (>10 keV). Hence, the samples must be metallic or metallized, to avoid charging effects. Both devices have an adjustable accelerating voltage of up to 30 kV, and a maximum magnification of 150000. Since 2005 we also own a Zeiss SUPRA 35, equipped with a field emission gun (fig 1). The acceleration voltage can be varied between 100 V and 30 kV, the maximum magnification is 900000x.

An interesting aspect is the extension of a SEM to an electron beam lithography system, which is able to write different shapes directly into an electron sensitive resist. To do so, it is necessary to navigate the electron beam arbitrarily across the sample, and to be able to blank it immediately. This functionality is provided by a Raith ElphyPlus system, in our case. By means of the included software, the electron sensitive resist can be exposed with a computer designed structure. Afterwards the subsequent micro structuring steps are applied.

Magnetit-Nanoteilchen — Fig. 2 depicts a SEM image of magnetite nanoparticles with organic shell. In addition, the SEM is equipped with a STEM detector for recording SEM images in the transmission mode.

2017

Comparison of Flower-shaped Iron Oxide Nanoclusters: Synthesis Strategies and Coatings
Helena Gavilan, Anja Kowalski, David Heinke, Abhilash Sugunan, Jens Sommertune, Mirian Varon, Lara K. Bogart, Oliver Posth, Lunjie Zeng, David González-Alonso, Christoph Balceris, Jeppe Fock, Erik Wetterskog, Cathrine Frandsen, Nicole Gehrke, Cordula Grüttner, Andrea Fornara, Frank Ludwig, Sabino Veintemillas-Verdaguer, Christer Johansson, and Maria Puerto Morales, Part. Part. Syst. Charact. (accepted)

Modelling plexcitons of periodic gold nanorod arrays with molecular components Bo Liu, Hongdan Yan, Rainer Stosch, Benedikt Wolfram, Martin Bröring, Andrey Bakin, Meinhard Schilling, Peter Lemmens Nanotechnology, Volume 28, Number 195201, 1--6 - 2017 https://doi.org/10.1088/1361-6528/aa67d8

Size analysis of single-core magnetic nanoparticles Frank Ludwig, Christoph Balceris, Thilo Viereck, Oliver Posth, Uwe Steinhoff, Helena Gavilan, Rocio Costo, Lunjie Zeng, Eva Olsson, Christian Jonasson, Christer Johansson J. Magn. Magn. Mater., Volume 427, page 19--24 - 2017 http://dx.doi.org/10.1016/j.jmmm.2016.11.113

2016

Diffusion-Controlled Synthesis of Magnetic Nanoparticles David Heinke, Nicole Gehrke, Daniel Schmidt, Uwe Steinhoff, Thilo Viereck, Hilke Remmer, Frank Ludwig, M. Posfai, Andreas Briel Internat. Journal on Magnetic Particle Imaging, Volume 2, page 1603001-1--4 - 2016 https://journal.iwmpi.org/index.php/iwmpi/article/view/25

Simultaneous Study of Brownian and Néel Relaxation Phenomena in Ferrofluids by Mössbauer Spectroscopy Joachim Landers, S. Salamon, Hilke Remmer, Frank Ludwig, Heiko Wende Nanoletters, Volume 16, page 1150--1155 - 2016 http://pubs.acs.org/doi/ipdf/10.1021/acs.nanolett.5b04409

2015

Classification of magnetic nanoparticle systems - synthesis, standardization and analysis methods in the NanoMag project Sara Bogren, Andrea Fornara, Frank Ludwig, Maria del Puerto Morales, Uwe Steinhoff, Mikkel F. Hansen, Olga Kazakova, Christer Johansson Int. J. Mol. Sci., Volume 16, page 20308--20325 - 2015 doi:10.3390/ijms160920308

Effective particle magnetic moment of multi-core particles
Fredrik Ahrentorp, Andrea Astalan, Jakob Blomgren, Christian Jonasson, Erik Wetterskog, Peter Svedlindh, Aidin Lak, Frank Ludwig, Leo J. van Ijzendoorn, Fritz Westphal, Cordula Grüttner, Nicole Gehrke, Stefan Gustafsson, Eva Olsson and Christer Johansson J. Magn. Magn. Mater., 380, 221–226, 2015 doi:10.1016/j.jmmm.2014.09.070

Magnetic characterization of clustered core magnetic nanoparticles for MPI Nicole Gehrke, David Heinke, Dietmar Eberbeck, Frank Ludwig, Thilo Wawrzik, Christian Kuhlmann, Briel Andreas IEEE Trans. Magn. 51, 5300204, 2015 doi: 10.1109/TMAG.2014.2358275

Polymer/iron oxide nanoparticle composites - a straight forward and scalable synthesis approach Jens Sommertune, Abhilash Sugunan, Anwar Ahniyaz, Rebecca Stjernberg Bejhed, Anne Sarwe, Christer Johansson, Christoph Balceris, Frank Ludwig, Andrea Fornara Int. J. Mol. Sci., Volume 16, page 19752--19768 - 2015 doi:10.3390/ijms160819752

Preparation of core-shell hybrid materials by producing a protein corona around magnetic nanoparticles Andreas Weidner, C Gräfe, M von der Lühe, Hilke Remmer, Joachim H. Clement, Dietmar Eberbeck, Frank Ludwig, Robert Müller, Felix H. Schacher, Silvio Dutz Nanoscale Res. Lett., Volume 10, page 282--1 - 11 - 2015 doi: 10.1186/s11671-015-0992-2

2014

Design of experiments for highly reproducible pulsed laser deposition of YBa2Cu3O7−δ
Meinhard Schilling, Alexander Guillaume, Jan M. Scholtyssek, Frank Ludwig J. Phys. D: Appl. Phys. 47, 034008-1 – 10, 2014
doi: 10.1088/0022-3727/47/3/034008

Direct Protein Detection in the Sample Solution by Monitoring Rotational Dynamics of Nickel Nanorods Stefan Schrittwieser, Frank Ludwig, Jan Dieckhoff, Andreas Tschöpe, Annegret Günther, Andreas Huetten, Hubert Brueckl, Jörg Schotter Small, Volume 10, Issue 2, 407–411, 2014 http://onlinelibrary.wiley.com/doi/10.1002/smll.201300023/full

Magnetic, structural and particle size analysis of single- and multi-core magnetic nanoparticles
F. Ludwig, O. Kazakova, L. Fernández Barquín, A. Fornara, L. Trahms, U. Steinhoff, P. Svedlindh, E. Wetterskog, Q. A. Pankhurst, P. Southern, P. Morales, M. F. Hansen, C. Frandsen, E. Olsson, S. Gustafsson, N. Gehrke, K. Lüdtke-Buzug, C. Grüttner, C. Jonasson, and C. Johansson IEEE Trans. Magn. 50, 5300204, 2014

2013

Highly stable monodisperse PEGylated iron oxide nanoparticle aqueous suspensions: a nontoxic tracer for homogeneous magnetic bioassays
Aidin Lak, Frank Ludwig, Jan Dieckhoff, Jan M. Scholtyssek, Oliver Goldmann, Heinrich Lünsdorf, Dietmar Eberbeck, Andreas Kornowski, Matthias Kraken, Fred J. Litterst, Kathrin Fiege, Petra Mischnick, Meinhard Schilling Nanoscale, Volume 5, page 11447-11455, 2013
DOI: 10.1039/C3NR02197A

Size Distribution and Magnetization Optimization of Single-Core Iron Oxide Nanoparticles by Exploiting Design of Experiment Methodology
Aidin Lak, Frank Ludwig, Jan M. Scholtyssek, Jan Dieckhoff, Kathrin Fiege, Meinhard Schilling, IEEE Trans. Magn., 49, 2013, 201-207
DOI: 10.1109/TMAG.2012.2224325

Tuning the magnetic properties of metal oxide nanocrystal heterostructures by cation exchange
Mykhailo Sytnyk, Raimund Kirchschlager, Maryna I. Bodnarchuk, Daniel Primetzhofer, Dominik Kriegner, Herbert Ennser, Julian Stangl, Peter Bauer, Michael Voith, Achim W. Hassel, Frank Krumeich, Frank Ludwig, Arno Meingast, Gerald Kothleitner, Maksym V. Kovalenko, Wolfgang Heiss Nanoletters, Volume 13, 586–593, 2013
http://pubs.acs.org/doi/abs/10.1021/nl304115r

2012

High-density array of Au nanowires coupled by plasmon modes
Yan Hong-Dan, Peter Lemmens, Johannes Ahrens, Martin Bröring, Sven Burger, Winfried Daum, Gerhard Lilienkamp, Sandra Korte, Aidin Lak, Meinhard Schilling
Acta Phys. Sin., Volume 61, Number 32, 237105-1–6, 2012
http://wulixb.iphy.ac.cn/CN/Y2012/V61/I23/237105
http://wulixb.iphy.ac.cn/EN/10.7498/aps.61.237105

Magnetic Particle Imaging: Exploring particle mobility
Thilo Wawrzik, Frank Ludwig, Meinhard Schilling
Magnetic Particle Imaging, Springer Proceedings in Physics, Volume 140, 16–23, 2012

Synthesis of Single-Core Iron Oxide Nanoparticles as a Potential Tracer for Magnetic Particle Imaging
Aidin Lak, Thilo Wawrzik, Frank Ludwig, Meinhard Schilling
Magnetic Particle Imaging, Springer Proceedings in Physics, Volume 140, 91–95, 2012

Tailoring defect structure and optical absorption of porous anodic aluminum oxide membranes
Yan Hong-Dan, Peter Lemmens, Dirk Wulferding, Jianmin Shi, Klaus Dieter Becker, Chengtian Lin, Aidin Lak, Meinhard Schilling
Materials Chemistry and Physics, Volume 135, 206-211, 2012
DOI: http://dx.doi.org/10.1016/j.matchemphys.2012.04.059

2010

Influence of Synthesis Parameters on Magnetization and Size of Iron Oxide Nanoparticles
A. Lak, F. Ludwig, I.-M. Grabs, G. Garnweitner and M. Schilling AIP Conference Proceedings Vol. 1311, 224–230 (2010)

2011

Atomic Force Microscope (AFM) Cantilevers as Encoder for Real-Time Displacement Measurements
Xiaomei Chen
Dissertation TU Braunschweig, 2011, ISBN: 978 3 86387 0799.
http://www.digibib.tu-bs.de/?docid=00041992

2010

Atomic force microscope cantilever as an encoding sensor for real-time displacement measurement
Xiaomei Chen, Ludger Koenders, Helmut Wolff, Frank Haertig, Meinhard Schilling
Measurement Science and Technology, Volume 21, Number 10, 1-8, 2010
DOI: 10.1088/0957-0233/21/10/105205

Imposed layer-by-layer growth of ZnO on GaN/sapphire substrates using pulsed laser interval deposition Alexander Hirsch, Christian Wille, Heiko Bremers, Uwe Rossow, Andreas Hangleiter, Frank Ludwig, Meinhard Schilling Thin Solid Films, Volume 519, 7683–7685, 2011
DOI: http://dx.doi.org/10.1016/j.tsf.2011.05.057

2009

Effect of HF concentration on physical and electronic properties of electrochemically formed nano-porous silicon
P. Kumar, Peter Lemmens, M. Ghosh, Frank Ludwig, Meinhard Schilling
J. Nanomater., Volume 2009, 728957-1–7, 2009

Fluxgate-Magnetrelaxometrie magnetischer Nanopartikel in der Bioanalytik
Erik Heim
Dissertation. TU Braunschweig 2009. ISBN: 3 86664 722 0.
http://www.digibib.tu-bs.de/?docid=00030987

2008

Influence of polymeric additives on biomimetic silica deposition on patterned microstructures
Olaf Helmecke, Alexander Hirsch, Peter Behrens, Henning Menzel
Journal of Colloid and Interface Science, Volume 321, 44, 2008

Microstructured reaction areas for the deposition of silica
Olaf Helmecke, Alexander Hirsch, Peter Behrens, Henning Menzel
Colloid Polym. Sci., Volume 286, 225, 2008

2007

Fluxgate magnetorelaxometry of superparamagnetic nanoparticles for hydrogel characterization
Erik Heim, Steffen Harling, Kai Pöhlig, Meinhard Schilling, Frank Ludwig, Henning Menzel
J. Magn. Magn. Mater., Volume 311, Number 1, 150–154, 2007

2004

In-situ RHEED analysis of the epitaxial overgrowth of SrTiO₃ and YBa₂Cu₃O₇ films for multilayer devices
M. Karger, E. Heim, F. Ludwig, M. Schilling
Institute of Physics Conference Series No. 181, edited by A. Andreone, G. P. Pepe, Chistiano and G. Masullo, Institute of Physics Publishing, Bristol (UK) and Philadelphia (USA), 1556–1560, 2004

Using Benzophenone-Functionalized Phosphonic Acid To Attach Thin Polymer Films to Titanium Surfaces
Nina Griep-Raming, Matthias Karger, Dirk Menzel
Langmuir, Volume 20, Number 26, 11811–11814, 2004

Nanotechnology

Microscopy

For All Visitors

For Students

Internal Tools

Contact