-
02/2009;
-
[show abstract]
[hide abstract]
ABSTRACT: Matter produced by organisms is remarkable. Evolutionary optimized properties, e.g. regarding hydrodynamic, aerodynamic, wetting and adhesive behavior, can already be found in the “simplest” forms of organisms. Euglena gracilis, a single-celled algal species, performs tasks as diverse as sensing the environment and reacting to it, converting and storing energy and metabolizing nutrients, living as a plant or an animal, depending on the environmental constraints.
We developed a preparation method for atomic force microscopy investigation of dried whole
Euglena cells in air and obtained data on whole cells as well as cell parts. Our studies corroborate
TEM, SEM and optical microscopy results. Furthermore, we found new features on the pellicle, and
set the ground for AFM force spectroscopy and viscoelastic studies on the nanoscale.
Materials Science Forum 07/2007; 555:411-416.
-
[show abstract]
[hide abstract]
ABSTRACT: We present first results on the generation of surface nanostuctures by slow HCI on cleaved CaF2 (111) surfaces. The CaF2 single crystals were irradiated with slow (v �1 a.u.) Xe44+ HCI from the Heidelberg-EBIT. Like for other ionic fluoride single crystals, ion-induced surface structures in CaF2 are known to be stable in atmospheric conditions at room temperature. After irradiation the crystals were investigated by scanning force microscopy. Topographic images reveal the generation of nanometric hillocks protruding from the surface. The number of hillocks per unit area is in agreement with the applied ion fluence. A discussion of the role of the potential energy as well as a comparison with observations for swift heavy ion irradiations of CaF2 single crystals are presented.
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 07/2007; 256:346-349. · 1.21 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Slow multiply charged ions are efficiently guided through nano-capillaries with
large aspect ratio in polyethylene terephthalate (PET), due to self-organized charging of the
inner capillary walls which prevents close collisions with the surface. In order to gain more
insight into this interesting phenomenon we have measured the 2-D scattering distribution of
transmitted ions during the charge-up process.
Journal of Physics: Conference Series 58, 319-322. 03/2007; 58:319-322.
-
El-Said A.S.,
Meissl W.,
Simon M.C.,
Crespo López-Urrutia J.R.,
Lemell C.,
Burgdörfer J.,
Gebeshuber I.C.,
Winter HP,
Ullrich J.,
Trautmann C.,
Toulemonde M., Aumayr F.
[show abstract]
[hide abstract]
ABSTRACT: We investigate the formation of nano-sized hillocks on the (111) surface of CaF2 single crystals by impact of slow highly charged ions.
Atomic force microscopy reveals a surprisingly sharp and well-defined threshold of potential energy carried into the collision of about
14 keV for hillock formation. Estimates of the energy density deposited suggest that the threshold is linked to a solid–liquid phase transition
(‘‘melting’’) on the nanoscale. With increasing potential energy, both the basal diameter and the height of the hillocks increase. The
present results reveal a remarkable similarity between the present predominantly potential energy driven process and track formation by
the thermal spike of swift (�GeV) heavy ions.
Nucl. Instr. Meth. Phys. Res. B: Beam Interactions with Materials and Atoms. 02/2007; 258:167-171.
-
09/2006: pages 27-53; , ISBN: 978-3-540-26909-0
-
[show abstract]
[hide abstract]
ABSTRACT: Many atomic force microscopes (AFM) are nowadays equipped with closed fluid cells. Most of these closed fluid cells have small volume, limiting the maximum sample size, and, furthermore, do not allowfor investigations in chemically aggressive environments such as solvents. The closed fluid cell for MFP-3D, the atomic force microscope from Asylum Research, Santa Barbara, CA, has a glass base and is mainly intended for investigations of flat transparent biological samples. Starting fromtheMFP-3D closed fluid cell, a fluid cell tailored for investigations in tribologically relevant environments, e.g. at extreme mechanical and chemical conditions which may vary with time, was developed. Samples of various shapes and sizes can thus be investigated in controlled environments, be they fluid (e.g. solvents) or gaseous (e.g. corrosive gases). First results of AFM nanotribology experiments using this fluid cell are presented. Among the systems of interest are additives diluted in solvents adsorbing to surfaces and spreading and persistence of ionic liquids on tribologically stressed surfaces.
ARCHIVE Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology 1994-1996 (vols 208-210) 05/2005; 223(J5):759-765. · 0.73 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Scanning probe microscopy offers interesting approaches to not only image but also manipulate samples in the micro- and nanoscale regime.
Atomic force microscopy became one of the most versatile microscopy methods in biology, since this type of microscopy works under ambient conditions and in many cases, no extensive sample preparation is necessary. From imaging single living cells to large protein molecules and even more interestingly protein-protein interactions in real time, to micro- and nanoscale investigations of mechanical parameters such as viscoelasticity, atomic force microscopy has proved a useful technique.
Imaging biomolecules at atomic resolution is a dream which might come true within the next few years. A powerful new technique is magnetic resonance force microscopy, combining three-dimensional magnetic resonance imaging with the excellent force sensitivity of the atomic force microscope. This type of microscopy opens the possibility of performing scanning probe magnetic resonance imaging with a sensitivity more than 10 million times better than the sensitivity of the medical magnetic resonance imaging devices for visualizing of organs in the human body. This improved sensitivity extends magnetic resonance imaging into the nanometer realm.
01/2005: pages 139-165; , ISBN: 978-1-4020-3614-9
-
[show abstract]
[hide abstract]
ABSTRACT: We have investigated by means of atomic force microscopy (AFM) single impacts of slow singly and multiply charged Ar ions on atomically clean insulator surfaces for LiF(1 0 0), SiO2(0 001) a-quartz, muscovite mica and sapphire c-plane Al2O3(0 0 0 1) crystals. The target samples have been continuously kept under UHV conditions by transferring them in a transportable UHV vault from the vacuum chamber for ion bombardment to the AFM instrument. Slow ion bombardment was accompanied by low-energy electron flooding to compensate for possible target surface charge-up. For Al2O3 clear ion-charge dependent surface defects in lateral and vertical directions give evidence for potential sputtering, which until now has only been demonstrated with thin polycrystalline insulator films.
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 07/2003; 205:751-757. · 1.21 Impact Factor
