Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition

• Adib Abou Chaaya,
• Roman Viter,
• Mikhael Bechelany,
• Zanda Alute,
• Donats Erts,
• Anastasiya Zalesskaya,
• Kristaps Kovalevskis,
• Vincent Rouessac,
• Valentyn Smyntyna and
• Philippe Miele

Beilstein J. Nanotechnol. 2013, 4, 690–698, doi:10.3762/bjnano.4.78

• electric field of the surface charge in the depletion layer would stimulate dissociation of excitons in ZnO [18][48]. The absorption spectra of ultrathin ZnO ALD films show that the defect states are present in the gap. The defect states at 3.08–3.14 eV formed by neutral Zn vacancies and oxygen

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

• Pavel V. Komarov,
• Pavel G. Khalatur and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 567–587, doi:10.3762/bjnano.4.65

• force for dissociation (association) of positively/negatively charged ions, H3O+ and SO3−, is dominantly of energetic or entropic nature, we examined the temperature dependence of pair correlation functions (PCFs) g+–(r) and the corresponding potential of mean force W+–(r) = –kBTlng+–(r). The value of W

• proton dissociation [57]. At the higher hydration level, λ = 10, practically all protons are dissociated and this "valence" peak is not visible. The main peak in gOH(r) is associated with the first coordination shell formed by water molecules and positively charged ions around the SO3 groups, giving an

• clearly demonstrate the formation of various proton complexes (Figure 13). The QMD simulations showed that the presence of water in the model nanochannel causes dissociation of –SO3H units resulting in the formation of the SO3−·H3O+ ion pairs. The dissociation and transfer of the hydrogen ion to the

The role of electron-stimulated desorption in focused electron beam induced deposition

• Willem F. van Dorp,
• Thomas W. Hansen,
• Jakob B. Wagner and
• Jeff T. M. De Hosson

Beilstein J. Nanotechnol. 2013, 4, 474–480, doi:10.3762/bjnano.4.56

• [9], nanowires [10], tips for probe microscopy [11], and magnetic nanostructures [12][13]. FEBIP is a complex process, in which many parameters are involved. Examples are the residence times of the precursor molecules on the surface, the cross section or the reaction rate of dissociation, the local

• in the reaction with the electrons and desorption to the gas phase: where g is the sticking factor, F is the gas flux, N0 is the density of adsorption sites in a monolayer, D is the diffusion coefficient, σ(E) is the cross section for dissociation, J is the electron flux, and τ is the residence time

• concentration gradient. The last two terms describe dissociation by the electron beam and desorption from the substrate to the gas phase. The growth rate, R (cm·s−1), can be defined as: with Vmolecule (cm3) being the volume of a deposited molecule. Equation 1 has two temperature-dependent terms: diffusion and

Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes

• Thomas Baumgärtel,
• Christian von Borczyskowski and
• Harald Graaf

Beilstein J. Nanotechnol. 2013, 4, 218–226, doi:10.3762/bjnano.4.22

• high dissociation energy (several 100 kJ/mol), and with the knowledge of their successful implementation on nanostructures, the whole realm of modular chemistry can be applied (e.g., “Click”-chemistry [18]). Mechanisms such as electrostatic binding or binding by intermolecular forces (e.g., polar

Photoresponse from single upright-standing ZnO nanorods explored by photoconductive AFM

• Igor Beinik,
• Markus Kratzer,
• Astrid Wachauer,
• Lin Wang,
• Yuri P. Piryatinski,
• Gerhard Brauer,
• Xin Yi Chen,
• Yuk Fan Hsu,
• Aleksandra B. Djurišić and
• Christian Teichert

Beilstein J. Nanotechnol. 2013, 4, 208–217, doi:10.3762/bjnano.4.21

• the current initially stays at the saturation level during the first cycle of the illumination, even when illumination is switched off, and then rapidly decays. In principle, this behavior can be caused by several mechanisms, such as water dissociation and desorption, recharging of defects, etc. We

• the emission of localized excitons. Therefore, the absorption of light with photon energies of 3.2 eV and higher may lead to the generation of excitons with possible subsequent dissociation into free charge carriers. The broad band visible in Figure 2b (integral spectrum) with the maximum at 504 nm is

Functionalization of vertically aligned carbon nanotubes

• Eloise Van Hooijdonk,
• Carla Bittencourt,
• Rony Snyders and
• Jean-François Colomer

Beilstein J. Nanotechnol. 2013, 4, 129–152, doi:10.3762/bjnano.4.14

• the four fundamental steps occurring during the CVD growth of CNTs: adsorption of the gas precursor molecule on the catalyst surface, dissociation of the precursor molecule, diffusion of the growth species in/on the catalyst particle, and nucleation and incorporation of carbon into the growing

• structure. Hoffman et al. [47] demonstrated that the limiting step in the determination of the activation energy for thermal CVD is the dissociation of the precursor molecule and, for PECVD, is the carbon diffusion on the catalyst. Thanks to the low temperatures in PECVD compared to the temperatures in

Catalytic activity of nanostructured Au: Scale effects versus bimetallic/bifunctional effects in low-temperature CO oxidation on nanoporous Au

• Lu-Cun Wang,
• Yi Zhong,
• Haijun Jin,
• Daniel Widmann,
• Jörg Weissmüller and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2013, 4, 111–128, doi:10.3762/bjnano.4.13

• with earlier proposals for Ag-contaminated submicron-size Au nanoparticles [34] and highly active mesoporous oxide-supported AuAg catalysts [35][36]. From calculations based on density functional theory, Moskaleva et al. found a significant reduction of the barrier for O2 dissociation in the vicinity

Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM

• Xiaoxing Ke,
• Carla Bittencourt,
• Sara Bals and
• Gustaaf Van Tendeloo

Beilstein J. Nanotechnol. 2013, 4, 77–86, doi:10.3762/bjnano.4.9

• distribution. Comparing the nanoclusters in the same column in which PE is increasing and dwell time is not varied, it can be seen that their average size and lateral density decreases. The higher lateral density indicates a higher dissociation probability at lower PE, where PE contributes more to the

• deposition process. Simultaneously, lower PE results in a smaller interaction volume and therefore leads to increasing yields of secondary electrons and backscattered secondary electrons , which all contribute to the dissociation process. When comparing the deposition in the same row in which PE is kept

• Figure 7a and Figure 7e as indicated by the circles, whereas the nanostructure of the CNT is well preserved. This effect has been reported in [45], which is attributed to the dissociation of intermediate amorphous carbon and defined as the first phase in electron irradiation. The second phase of

Horizontal versus vertical charge and energy transfer in hybrid assemblies of semiconductor nanoparticles

• Gilad Gotesman,
• Rahamim Guliamov and
• Ron Naaman

Beilstein J. Nanotechnol. 2012, 3, 629–636, doi:10.3762/bjnano.3.72

• type of transfer process. Wu et al. studied charge separation in type-II heterojunction assemblies of CdSe–CdTe NPs as a function of linker length [23]. They found that for longer linkers, the charge transfer efficiency is smaller. In another study, photogenerated exciton dissociation in PbS NP thin

Focused electron beam induced deposition: A perspective

• Michael Huth,
• Fabrizio Porrati,
• Christian Schwalb,
• Marcel Winhold,
• Roland Sachser,
• Maja Dukic,
• Jonathan Adams and
• Georg Fantner

Beilstein J. Nanotechnol. 2012, 3, 597–619, doi:10.3762/bjnano.3.70

• review of the fundamentals FEBID in a nutshell: The FEBID process is based on the electron-induced dissociation of a molecular precursor previously adsorbed on a substrate surface and constantly replenished by a gas-supply system. In most instances the gas-supply or gas-injection system consists of a

• the substrate a precursor must have a sufficiently long residence time τ on the surface, typically lasting microseconds to milliseconds. Otherwise, at typical energy-dependent dissociation cross sections σ(E) of 10−3 to 10−2 nm2 in the energy range below 500 eV for metal–organic precursors, the

• deposition yield would be too small. On the other hand, the volatile organic dissociation products should readily desorb to prevent their usually undesired inclusion in the deposit. Depending on the targeted functionality of the FEBID structure, several different precursor classes are employed, such as

Spontaneous dissociation of Co₂(CO)₈ and autocatalytic growth of Co on SiO₂: A combined experimental and theoretical investigation

• Kaliappan Muthukumar,
• Harald O. Jeschke,
• Roser Valentí,
• Evgeniya Begun,
• Johannes Schwenk,
• Fabrizio Porrati and
• Michael Huth

Beilstein J. Nanotechnol. 2012, 3, 546–555, doi:10.3762/bjnano.3.63

• , namely by air plasma cleaning or a focused electron beam pre-irradiation. We observe a spontaneous dissociation of the precursor molecules as well as autodeposition of cobalt on the pretreated SiO2 surfaces. We also find that the differences in metal content and relative stability of these deposits

• depend on the pretreatment conditions of the substrate. Transport measurements of these deposits are also presented. We are led to assume that the degree of passivation of the SiO2 surface by hydroxyl groups is an important controlling factor in the dissociation process. Our calculations of various slab

• dissociation of the precursor molecule. In view of these calculations, we discuss the origin of this dissociation and the subsequent autocatalysis. Keywords: Co2(CO)8; deposition; dissociation; EBID; FEBID; precursor; radiation-induced nanostructures; Introduction In recent years, focused electron beam

Directed deposition of silicon nanowires using neopentasilane as precursor and gold as catalyst

• Britta Kämpken,
• Verena Wulf,
• Norbert Auner,
• Marcel Winhold,
• Michael Huth,
• Daniel Rhinow and
• Andreas Terfort

Beilstein J. Nanotechnol. 2012, 3, 535–545, doi:10.3762/bjnano.3.62

• such as octachlorotrisilane [36] and disilane [37] have similar properties to their monomeric analogues, although both of these precursors are reported to have an exceptionally high growth rate compared to their analogous monosilanes. This is due to the fact that the dissociation energy of the Si–Si

Radiation-induced nanostructures: Formation processes and applications

• Michael Huth

Beilstein J. Nanotechnol. 2012, 3, 533–534, doi:10.3762/bjnano.3.61

• tissue, define a principle of nanostructure formation by destructive means. But there is a deeper connection on the microscopic level. In FEBID the dominating contribution to the dissociation yield stems from low-energy electrons in the energy range between a few to several hundred electron volts

• . Different processes, such as dissociative electron attachment, neutral dissociation or dissociative ionization act together in breaking selected bonds in (mostly) metal–organic precursor molecules. On the other hand, low-energy electrons also play a role in the radiation damage induced by ionizing radiation

• -energy part of the energy spectrum, i.e., below about 5 keV, the biological effectiveness increases strongly. This increased effectiveness indicates a parallel to the FEBID process and points towards an analogous increase in the dissociation cross section at low electron energies. A full microscopic

Low-temperature synthesis of carbon nanotubes on indium tin oxide electrodes for organic solar cells

• Andrea Capasso,
• Luigi Salamandra,
• Aldo Di Carlo,
• John M. Bell and
• Nunzio Motta

Beilstein J. Nanotechnol. 2012, 3, 524–532, doi:10.3762/bjnano.3.60

• [11]. In fact, CNTs were initially suggested as a replacement for fullerene [12], because of their ability to create percolation paths through the heterostructure, while providing electron–hole dissociation sites. Being that the electron mobility in fullerenes is rather low [13][14][15], the initial

• with a large interface area over which a strong electric field would lead to a high probability of exciton dissociation [16]. However, the lack of control over the selection of the CNTs has made their integration with polymers quite unsuccessful so far [17], as recently suggested by photoluminescence

• ITO film to a hydrogen atmosphere at 550 °C (and the probable creation of atomic hydrogen coming from the dissociation of either H2 or C2H2, perhaps enabled by the metal catalyst layer) enables the formation of small clusters of metallic indium, which coalesce during the CVD to form spherical

Macromolecular shape and interactions in layer-by-layer assemblies within cylindrical nanopores

• Thomas D. Lazzara,
• K. H. Aaron Lau,
• Wolfgang Knoll,
• Andreas Janshoff and
• Claudia Steinem

Beilstein J. Nanotechnol. 2012, 3, 475–484, doi:10.3762/bjnano.3.54

• dissociation of the charged groups of the linear-PEs used in this study generates LbL multilayer films that are essentially uncharged because of the strong ionic interactions between the polyelectrolyte polymers. The film is basically precipitated onto the surface and forms compact layers. However, LbL films

Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

• Mihai E. Vaida,
• Robert Tchitnga and
• Thorsten M. Bernhardt

Beilstein J. Nanotechnol. 2011, 2, 618–627, doi:10.3762/bjnano.2.65

• dissociation was observed in the case of methyl bromide. This was interpreted as being due to a considerable energetic down-shift of the electronic A-band states of methyl bromide by about 1.5 eV through interaction with the gold substrate. Finally, for methyl chloride no photofragmentation could be detected

• to be a consequence of methyl iodide dissociation followed by coupling between the methyl radicals. Since the temperature at which ethane appears is higher than that for the ethane molecular desorption (below 100 K), it was concluded that the ethane formation is the rate-determining step as opposed

• to the desorption [11]. Furthermore, it can be assumed that the methyl iodide molecules involved in the thermal reaction are adsorbed on defect sites and dissociate close to the ethane-appearance temperature (300 K) [11]. The remaining iodine atoms resulting from dissociation should desorb from the

Characterization of protein adsorption onto FePt nanoparticles using dual-focus fluorescence correlation spectroscopy

• Pauline Maffre,
• Karin Nienhaus,
• Faheem Amin,
• Wolfgang J. Parak and
• G. Ulrich Nienhaus

Beilstein J. Nanotechnol. 2011, 2, 374–383, doi:10.3762/bjnano.2.43

• , indicating that the proteins bind on the nanoparticles in specific orientations. The equilibrium dissociation coefficients, measuring the affinity of the proteins to the nanoparticles, were observed to differ by almost four orders of magnitude. These variations can be understood in terms of the electrostatic

• but fluctuates in time due to incessant protein association and dissociation events. Upon biofluid exposure, the NP surface will quickly become coated with those proteins that are prevalent in the fluid and that have high binding rate coefficients. However, these proteins may subsequently be replaced

• model the dependence of N on the concentration of free protein, [P], by the Hill equation [11], Here, the equilibrium dissociation coefficient, K’D, denotes the midpoint of the transition, i.e., the concentration of protein molecules free in the solution at half coverage. It quantifies the strength of

Zirconium nanoparticles prepared by the reduction of zirconium oxide using the RAPET method

• Michal Eshed,
• Swati Pol,
• Aharon Gedanken and
• Mahalingam Balasubramanian

Beilstein J. Nanotechnol. 2011, 2, 198–203, doi:10.3762/bjnano.2.23

• Temperatures), and is described elsewhere in detail [11]. In general, a stainless steel cell is filled with a single reactant (or a combination of reactants) and heated at an appropriate temperature under its autogenic pressure. The pressure is generated by the thermal dissociation of reactants and the Let-Lok

Magnetic nanoparticles for biomedical NMR-based diagnostics

• Huilin Shao,
• Tae-Jong Yoon,
• Monty Liong,
• Ralph Weissleder and
• Hakho Lee

Beilstein J. Nanotechnol. 2010, 1, 142–154, doi:10.3762/bjnano.1.17

• within the DEVD site, which led to a corresponding increase in T2 relaxation time (Figure 5c). This dissociation was not observed when a specific caspase-3 inhibitor was added. A similar reverse switching strategy has been used to detect trypsin, renin, and matrix metalloproteinase 2 activities [57

• caspase-3. MNPs were clustered with a peptide linker containing the sequence DEVD and were rapidly dissociated upon the activity of caspase-3. This dissociation was not observed when a specific caspase-3 inhibitor was added. The enzyme-dependent disassembly of the MNP clusters resulted in an increase in

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

• Alexander Weddemann,
• Inga Ennen,
• Anna Regtmeier,
• Camelia Albon,
• Annalena Wolff,
• Katrin Eckstädt,
• Nadine Mill,
• Michael K.-H. Peter,
• Jochen Mattay,
• Carolin Plattner,
• Norbert Sewald and
• Andreas Hütten

Beilstein J. Nanotechnol. 2010, 1, 75–93, doi:10.3762/bjnano.1.10

• ligands is given by the dissociation constant De. A small value of De corresponds to a hard to break bond between the metal surface and the ligand and, consequently, in reduced particle growth. The size of the dissociation constant may strongly vary, depending on the above mentioned binding affinities to

• different crystal planes. Crystals with a simple cubic symmetry result in an isotropic value which entails spherical particles (Figure 3(a)). However, if non-cubic crystal lattices are present, the dissociation constants may depend on the crystal plane and growth in specific directions is promoted [10][15

• present. The single binding motive of TOPO results in a constant dissociation along the particle surface and, thus, an isotropic growth. The multiple binding motives of the ligand mixture (b) lead to different binding affinities along different crystal planes. Therefore, the growth in specific directions

Sensing surface PEGylation with microcantilevers

• Natalija Backmann,
• Natascha Kappeler,
• Thomas Braun,
• François Huber,
• Hans-Peter Lang,
• Christoph Gerber and
• Roderick Y. H. Lim

Beilstein J. Nanotechnol. 2010, 1, 3–13, doi:10.3762/bjnano.1.2

• dissociation processes. Here, we find that the Langmuir fit appropriately describes the experimental curves at PEG concentrations below 50 μM (Figure 4B). Interestingly, we observed a clear deviation from the Langmuir behavior at 50 μM and above. This could arise due to the sensitivity of the microcantilever

• concentration appears to promote the physical adsorption of non-tethererd PEG chains on the grafted monolayer after saturation is reached at 100 μM PEG concentration. Indeed, the dissociation profile of the binding curve obtained at 500 μM (Figure 3) seems to support such a view. The exponential fit of the