Control theory for scanning probe microscopy revisited

• Julian Stirling

Beilstein J. Nanotechnol. 2014, 5, 337–345, doi:10.3762/bjnano.5.38

• tracking without a high derivative component [13], which is entirely at odds with experimental observations. This paper employs analysis of specific SPM PI controllers to provide a more appropriate method for modelling such systems. Results and Discussion When modelling an SPM feedback loop we must first

• gone unnoticed to date because it has been ‘disguised’ by the more complicated modelling of the response of the various other electrical and electromechanical components of the SPM (amplifiers, piezoelectric actuators). It is helpful to draw an analogy with the most commonly considered control system

• is a 1/(Kp + 1) of the required extension. This has previously been mistaken as a steady-state error common to proportional controllers [9]. However, when plotted without any modelling of other components it becomes clear that it results from the controller that only acts to the initial impulse. From

Confinement dependence of electro-catalysts for hydrogen evolution from water splitting

• Mikaela Lindgren and
• Itai Panas

Beilstein J. Nanotechnol. 2014, 5, 195–201, doi:10.3762/bjnano.5.21

• upon H2 release, violating Sabatiers principle. In conclusion, the present approach offers a complementary computational strategy to rank catalysts for HER from water splitting. The complex modelling of heterogeneous HER electro-catalysis at the interface between composite catalyst/support and a water

The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

• Jakob G. Howalt and
• Tejs Vegge

Beilstein J. Nanotechnol. 2014, 5, 111–120, doi:10.3762/bjnano.5.11

• adsorbates (N, H, O, NH, etc.); these were carried out using the BFGS and FIRE [18] optimizers within ASE. Electrochemical modelling The procedure for electrochemical reduction of nitrogen molecules through the associative mechanism is outlined in [2][16]. It was shown that the associative mechanism is the

Structural development and energy dissipation in simulated silicon apices

• Samuel Paul Jarvis,
• Lev Kantorovich and
• Philip Moriarty

Beilstein J. Nanotechnol. 2013, 4, 941–948, doi:10.3762/bjnano.4.106

• temperature. This is evidenced by numerous studies, which have shown the manipulation of single atoms in both lateral and vertical directions, which was made possible by the strong covalent nature of the bonding [25]. As such, understanding the AFM tip structure and successfully modelling experimental

Ellipsometry and XPS comparative studies of thermal and plasma enhanced atomic layer deposited Al₂O₃-films

• Jörg Haeberle,
• Karsten Henkel,
• Hassan Gargouri,
• Franziska Naumann,
• Bernd Gruska,
• Michael Arens,
• Massimo Tallarida and
• Dieter Schmeißer

Beilstein J. Nanotechnol. 2013, 4, 732–742, doi:10.3762/bjnano.4.83

• spectroscopic ellipsometry in the middle infrared wavelength range (MIR) the SENDIRA ellipsometer from SENTECH Instruments GmbH was performed. A Step scan analyser for high spectroscopic accuracy was used at an angle of incidence of 70°. Modelling was carried out using SpectraRay 3 software. The model layer

Novel composite Zr/PBI-O-PhT membranes for HT-PEFC applications

• Mikhail S. Kondratenko,
• Igor I. Ponomarev,
• Marat O. Gallyamov,
• Dmitry Y. Razorenov,
• Yulia A. Volkova,
• Elena P. Kharitonova and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 481–492, doi:10.3762/bjnano.4.57

• resistance of a cell, Rm, (mainly membrane resistance); the distributed resistance of proton transport in the cathode AL, Rel; the charge transfer resistance, Rct; and the double layer capacitance, C (Figure 2). Fitting of the impedance spectra was performed by means of the Zview modelling software using the

• lead to a lowering of the PA doping level and a lower conductivity due to a higher degree of crosslinking. Chemical structure of poly[oxy-3,3-bis(4′-benzimidazol-2″-ylphenyl)phtalide-5″(6″)-diyl] (PBI-O-PhT). Equivalent circuit with a transmission line for modelling the impedance response of the active

A highly pH-sensitive nanowire field-effect transistor based on silicon on insulator

• Denis E. Presnov,
• Sergey V. Amitonov,
• Pavel A. Krutitskii,
• Valentina V. Kolybasova,
• Igor A. Devyatov,
• Vladimir A. Krupenin and
• Igor I. Soloviev

Beilstein J. Nanotechnol. 2013, 4, 330–335, doi:10.3762/bjnano.4.38

• transport-current fluctuations SI by considering an equivalent scheme with a series connection of resistors modelling NW and Schottky barriers with uncorrelated fluctuation generators: Our four-probe measurements of the NW resistance R and Schottky barrier resistance RB at room temperature show that R >> RB

Determining cantilever stiffness from thermal noise

• Jannis Lübbe,
• Matthias Temmen,
• Philipp Rahe,
• Angelika Kühnle and
• Michael Reichling

Beilstein J. Nanotechnol. 2013, 4, 227–233, doi:10.3762/bjnano.4.23

• derived from a thermal measurement and do not require any modelling to relate geometric cantilever properties to oscillation properties. Displacement noise spectral density measured for the fundamental mode of cantilever V 4. Measurements represent the average of 50,000 spectra. (a) Measurement yielding

Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

• Jannis Lübbe,
• Matthias Temmen,
• Sebastian Rode,
• Philipp Rahe,
• Angelika Kühnle and
• Michael Reichling

Beilstein J. Nanotechnol. 2013, 4, 32–44, doi:10.3762/bjnano.4.4

• of modelling noise in the NC-AFM system in combination with the experimental practice described here provides a clear guideline for system design and the choice of experimental parameters for thermal-noise-limited operation. The analysis shows that for a noise-optimised NC-AFM measurement, the right

Calculation of the effect of tip geometry on noncontact atomic force microscopy using a qPlus sensor

• Julian Stirling and
• Gordon A. Shaw

Beilstein J. Nanotechnol. 2013, 4, 10–19, doi:10.3762/bjnano.4.2

• imaging in the first eigenmode. We calculate the effect the lateral motion has on the measured frequency shift, and hence, how this affects calibration, imaging, and spectroscopy. Results and Discussion Modelling the tine of the qPlus sensor as an Euler–Bernoulli beam [16] of length L, we can write where

Towards atomic resolution in sodium titanate nanotubes using near-edge X-ray-absorption fine-structure spectromicroscopy combined with multichannel multiple-scattering calculations

• Carla Bittencourt,
• Peter Krüger,
• Maureen J. Lagos,
• Xiaoxing Ke,
• Gustaaf Van Tendeloo,
• Chris Ewels,
• Polona Umek and
• Peter Guttmann

Beilstein J. Nanotechnol. 2012, 3, 789–797, doi:10.3762/bjnano.3.88

• theoretical modelling. Taking the example of isolated bundles of hydrothermally prepared sodium titanate nanotubes ((Na,H)TiNTs) we are able to unravel the complex nanoscale structure from the NEXAFS–TXM data using multichannel multiple-scattering calculations, to the extent of being able to associate

• ]. However, we show in the current study that the combination of NEXAFS–TXM with high-level theoretical modelling allows us to move beyond this spatial-resolution limit and extract more spatially refined information [8]. Indeed this combination of theory and spectroscopy paves the way towards atomic-scale

• layers of the nanostructure. The excellent agreement between the experimental data and the theoretical modelling confirms the assignment of the (Na,H)TiNT structure to a layered titanate of the H2TinO2n+1 family. High-level spectroscopic modelling appears to be an important way to extend further the

Analysis of fluid flow around a beating artificial cilium

• Mojca Vilfan,
• Gašper Kokot,
• Andrej Vilfan,
• Natan Osterman,
• Blaž Kavčič,
• Igor Poberaj and
• Dušan Babič

Beilstein J. Nanotechnol. 2012, 3, 163–171, doi:10.3762/bjnano.3.16

• experiment. Analytical calculation of the average flow velocity A very basic approach to modelling the flows around a beating cilium, regardless of its precise beat pattern, consists of replacing the cilium with a small hypothetical particle circling along a tilted elliptical trajectory [19]. We have shown

Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100) at 5 K: Probing the probe

• Adam Sweetman,
• Sam Jarvis,
• Rosanna Danza and
• Philip Moriarty

Beilstein J. Nanotechnol. 2012, 3, 25–32, doi:10.3762/bjnano.3.3

• the modelling community that will lead to the investigation of more-realistic tip structures, and their respective tip–sample interaction and contrast mechanisms. The role of the tip was investigated by imaging the well studied Si(100) surface. The Si(100) surface is now understood to form a stable c

• results will inspire further debate in the modelling community, and help further understanding of contrast mechanisms in NC-AFM imaging of semiconductor surfaces. In particular we note that by operating at zero bias, the influence of tunnelling electrons is eliminated, highlighting the fact that the

Distance dependence of near-field fluorescence enhancement and quenching of single quantum dots

• Volker Walhorn,
• Jan Paskarbeit,
• Heinrich Gotthard Frey,
• Alexander Harder and
• Dario Anselmetti

Beilstein J. Nanotechnol. 2011, 2, 645–652, doi:10.3762/bjnano.2.68

• the tip distance. Modelling the system with a MDP approach unveiled the multivalent interplay of incident and emitted electromagnetic fields at the boundary of different media. Our results represent an important step en route towards being able to controllably address and manipulate fluorescently

Intermolecular vs molecule–substrate interactions: A combined STM and theoretical study of supramolecular phases on graphene/Ru(0001)

• Michael Roos,
• Benedikt Uhl,
• Daniela Künzel,
• Harry E. Hoster,
• Axel Groß and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2011, 2, 365–373, doi:10.3762/bjnano.2.42

• theoretical study [39]. These surfaces coordinates were then kept fixed in the subsequent relaxation of adsorbed PTCDA and BTP molecules. The interactions between molecule–graphene and molecule–Ru were treated as being additive. For the modelling of the molecule–graphene interactions, a single molecule was

Superhydrophobicity in perfection: the outstanding properties of the lotus leaf

• Hans J. Ensikat,
• Petra Ditsche-Kuru,
• Christoph Neinhuis and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 152–161, doi:10.3762/bjnano.2.19

• contact with water [20] and to prove the theories such as those of Wenzel or Cassie and Baxter. For precise modelling of the behaviour of natural water repellent surfaces, an exact knowledge of the chemical composition and molecular structure are essential. Resistance against environmental stress The

Capillary origami: superhydrophobic ribbon surfaces and liquid marbles

• Glen McHale,
• Michael I. Newton,
• Neil J. Shirtcliffe and
• Nicasio R. Geraldi

Beilstein J. Nanotechnol. 2011, 2, 145–151, doi:10.3762/bjnano.2.18

• roughness factor rW and using the definition of the equilibrium contact angle on a rigid substrate of cosθe = (γSV − γSL)/γLV gives, Defining the Cassie–Baxter combination cosθCB = φscosθe − (1−φs), which is familiar from the modelling of droplets on superhydrophobic surfaces, gives, The similarity of

The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction

• W. Merlijn van Spengen,
• Viviane Turq and
• Joost W. M. Frenken

Beilstein J. Nanotechnol. 2010, 1, 163–171, doi:10.3762/bjnano.1.20

• systems (MEMS) devices with sliding surfaces. This new model is shown to exhibit the same features as previously reported experimental MEMS friction loop data. The correlation function of the surface roughness is shown to play a critical role in the modelling. It is experimentally obtained by probing the