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21.
Karakurt I Leiderer P Boneberg J 《Langmuir : the ACS journal of surfaces and colloids》2006,22(6):2415-2417
A study of the self-organization of colloidal particles during the evaporation of particle solutions on chemically patterned surfaces is presented. On a surface with hydrophilic and hydrophobic regions, colloidal particles form compact structures on the hydrophilic sites. When a colloidal solution containing a mixture of particles with a variation in size is used, the number density of each type of particle deposited on the hydrophilic islands after evaporation decreases with increasing particle size. This makes it possible to produce a concentration gradient of the particles on islands of different sizes. It is shown that this technique could allow for particle separation. 相似文献
22.
J. Boneberg M. Lohrmann M. Böhmisch F. Burmeister M. Lux-Steiner P. Leiderer 《Zeitschrift für Physik B Condensed Matter》1995,99(1):567-570
We report on the conditions for the growth of triangular structures on WSe2 surfaces in scanning tunneling experiments with a vertical dimension of one layer (Se-W-Se) and up to 200 nm in horizontal
direction. Experiments carried out in different atmospheres (ambient air, dry N2, dry O2) suggest that the growth is directly related to the presence of a thin physisorbed water layer on the surface of WSe2. Furthermore examinations under different scanning and bias conditions show that the electric field of the tip induces the
growth of these nanometer structures. 相似文献
23.
The fluctuations of the position of monatomic steps on Ag(111) are investigated by scanning tunneling microscopy (STM). We analyze the influence of tip–sample interaction by varying the gap impedance over more than two orders of magnitude. For tunneling tips providing a weak tip–sample interaction, we show that the step position autocorrelation function remains essentially unaltered. In this unperturbed case, the kinetics of step fluctuations are found to be dominated by one-dimensional mass transport. For larger variations of the tip–sample distance or for less favorable tip configurations, we observe a tip-induced increase of the step fluctuations. Our measurements suggest that this effect is caused rather by short-range forces than by the electric field in the tunneling gap. 相似文献
24.
P. Frank F. Lang M. Mosbacher J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》2008,93(1):1-4
Steam Laser Cleaning with a pulsed infrared laser source is investigated. The infrared light is tuned to the absorption maximum
of water (λ=2.94 μm, 10 ns), whereas the substrates used are transparent (glass, silicon). Thus a thin liquid water layer condensed on
top of the contaminated substrate is rapidly heated. The pressure generated during the subsequent phase explosion generates
a cleaning force which exceeds the adhesion of the particles. We examine the cleaning threshold in single shot experiments
for particles sized from 1 μm down to 300 nm. 相似文献
25.
Uwe Osswald Prof. Dr. Johannes Boneberg Prof. Dr. Valentin Wittmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(27):e202200267
Multivalent receptor–ligand binding is a key principle in a plethora of biological recognition processes. Immense binding affinities can be achieved with the correct spatial orientation of the ligands. Accordingly, the incorporation of photoswitches, which can be used to reversibly change the spatial orientation of molecules, into multivalent ligands is a means to alter the binding affinity and possibly also the binding mode of such ligands. We report a divalent ligand for the model lectin wheat germ agglutinin (WGA) containing an arylazopyrazole photoswitch. This switch, which has recently been introduced as an alternative to the more commonly used azobenzene moiety, is characterized by almost quantitative E/Z photoswitching in both directions, high quantum yields, and high thermal stability of the Z isomer. The ligand was designed in a way that only one of the isomers is able to bridge adjacent binding sites of WGA leading to a chelating binding mode. Photoswitching induces an unprecedentedly high change in lectin binding affinity as determined by isothermal titration calorimetry (ITC). Furthermore, additional dynamic light scattering (DLS) data suggest that the binding mode of the ligand changes from chelating binding of the E isomer to crosslinking binding of the Z isomer. 相似文献
26.
S. Riedel M. Schmotz P. Leiderer J. Boneberg 《Applied Physics A: Materials Science & Processing》2010,101(2):309-312
We show that nanosecond pulsed laser interference can be used to structure surfaces on a nanoscale. With this method, we are able to create hollow structures on various thin films like Ta, Ni, Au, Cu, Co, and NiTi. We find that the structuring mechanism is related to the mechanical effect of thermal expansion upon melting. To corroborate this model, we study materials with an abnormal behavior at the melting point like Si, Ge, or Bi, as they contract upon melting. 相似文献
27.
J. Boneberg S. Briaudeau Z. Demirplak V. Dobler P. Leiderer 《Applied Physics A: Materials Science & Processing》1999,69(7):S557-S560
An optical setup for the measurement of acoustic shock waves is demonstrated experimentally. This sensor, which is based on surface plasmon excitation, provides ns time resolution as well as 7m lateral resolution. Initial experiments with laser-induced plasma generation in a water cell already show that in a simple geometry high lateral resolution gives new insight into the ongoing processes. 相似文献
28.
O. Yavas A. Schilling J. Bischof J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》1997,64(4):331-339
with a pressure pulse width of . Additionally, the phase of an acoustic pulse is observed to change upon reflection at the liquid–solid interface if bubbles
are present, providing a direct proof for laser-induced bubbles.
Received: 5 December 1996/Accepted: 6 January
1997 相似文献
29.
P. Frank J. Graf F. Lang J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》2010,101(1):7-11
The ejection dynamics of nanometer-thin fluid isopropanol and solid CO2 films are investigated. The films are deposited on a silicon substrate, which is rapidly heated by a nanosecond laser pulse
(Nd:YAG, 532 nm). A small fraction of material at the interface evaporates and the film on top is ejected as an intact layer.
The kinetic energies of the two different films with thicknesses between 100 nm and 1 μm give an insight into the dynamics
of a flying lamella. 相似文献
30.
M. Mosbacher H.-J. Münzer J. Zimmermann J. Solis J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》2001,72(1):41-44
We report on the role of local optical field enhancement in the neighborhood of particles during dry laser cleaning (DLC)
of silicon wafer surfaces. Samples covered with spherical colloidal particles (PS, SiO2) and arbitrarily shaped Al2O3 particles with diameters from 320–1700 nm were cleaned using laser pulses with durations from 150 fs to 6.5 ns and wavelengths
ranging from 400–800 nm. Cleaned areas were investigated with scanning electron and atomic force microscopy. Holes in the
substrate with diameters of 200–400 nm and depths of 10–80 nm, depending on the irradiation conditions, were found at the
former positions of the particles. For all pulse durations analyzed (fs, ps, ns), holes are created at laser fluences as small
as the threshold fluence. Calculations of the optical field intensities in the particles’ neighbourhood by applying Mie theory
suggest that enhancement of the incident laser intensity in the near field of the particles is responsible for these effects.
DLC for sub-ns pulses seems to be governed by the local ablation of the substrate rather than by surface acceleration.
Received: 31 May 2000 / Accepted: 7 September 2000 / Published online: 22 November 2000 相似文献