Conductance through single biphenyl molecules: symmetric and asymmetric coupling to electrodes

• Karthiga Kanthasamy and
• Herbert Pfnür

Beilstein J. Nanotechnol. 2015, 6, 1690–1697, doi:10.3762/bjnano.6.171

• -curves have been observed even for such symmetric molecules with an STM-based technique [50]. This finding may be due to the inherent asymmetric contact geometry and different chemical environment. In order to get more quantitative insight, we used the single level resonance model, based on the Landauer

• both molecules with only slight asymmetries in the I–V-curves for the asymmetric molecule. While the results for biphenyl dithiol are in fair agreement with those carried out previously in dry MCBJs, the contact formation seems to be significantly different in other experiments, as, e.g., with an STM

Transformations of PTCDA structures on rutile TiO₂ induced by thermal annealing and intermolecular forces

• Szymon Godlewski,
• Jakub S. Prauzner-Bechcicki,
• Thilo Glatzel,
• Ernst Meyer and
• Marek Szymoński

Beilstein J. Nanotechnol. 2015, 6, 1498–1507, doi:10.3762/bjnano.6.155

• desired assemblies. Differences between PTCDA/TiO2(110) and PTCDA/TiO2(011) systems obtained through identical experimental procedures are discussed. Keywords: PTCDA, TiO2, rutile, self-assembly, STM; Introduction Molecular self-assembly appears to be a very powerful and versatile tool for the formation

• same authors discussed the charge transfer timescale at the PTCDA/TiO2(110) interface with respect to the molecular orientation [38]. Tekiel et al. [39] presented scanning tunnelling microscopy (STM) studies of the PTCDA/TiO2(011) system focused on molecular chain formation. The molecules were arranged

• surface is shown in Figure 1. Despite the presence of outstanding oxygen atoms, the STM mapping is largely dominated by electronic effects. As a result, the bright rows running along the [001] direction that are clearly visible in the STM images correspond to titanium rows, while the oxygen rows are

Enhanced fullerene–Au(111) coupling in (2√3 × 2√3)R30° superstructures with intermolecular interactions

• Michael Paßens,
• Rainer Waser and
• Silvia Karthäuser

Beilstein J. Nanotechnol. 2015, 6, 1421–1431, doi:10.3762/bjnano.6.147

• –metal interface. First systematic studies of close packed fullerene thin films on Au(111) surfaces using scanning tunnelling microscopy (STM) were performed by Altman and Colton [8][9][10]. They observed two structural arrangements, the (2√3 × 2√3)R30° and the uniform (7 × 7)R0° superlattices, with the

• unit cell of the C60 overlayer aligned along the [11−2] and [10−1] directions of the Au(111) surface, respectively. Low energy electron diffraction (LEED) measurements by Tzeng et al. [11] revealed a R14° structure, which was confirmed by STM measurements later on [12][13]. In addition, the structure

• could be identified as a (√589 × √589)R14.5° lattice [12] with 49 molecules. Usually, the periodicity and orientation of molecular self-assembled superstructures with respect to the underlying substrate are identified by the apparent height of the respective molecules using STM technique [14]. However

Nano-contact microscopy of supracrystals

• Adam Sweetman,
• Nicolas Goubet,
• Ioannis Lekkas,
• Marie Paule Pileni and
• Philip Moriarty

Beilstein J. Nanotechnol. 2015, 6, 1229–1236, doi:10.3762/bjnano.6.126

• distribution at the nanocrystal surface. Conclusion: Our combined STM–AFM measurements show that the contrast mechanism underpinning high resolution imaging of nanoparticle supracrystals involves a form of nanoscale contact imaging, rather than the through-vacuum tunnelling which underpins traditional

• thick (i.e, ≈700 nanoparticle layers) are sufficiently conductive for STM and scanning tunnelling spectroscopy (STS) studies. However, not only are STM and STS measurements possible, but the quality of imaging is comparable to that attained on monolayer (or submonolayer) coverages of nanoparticles on

• various substrates [14][15] (see, in particular, Figure 7a of Yang et al. [11].) However, bias voltages significantly higher than those conventionally used in STM measurements (as high as 9 V [13]) were sometimes necessary to image thick precipitated supracrystals. In addition to the unexpected imaging

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

• Henrry M. Osorio,
• Santiago Martín,
• María Carmen López,
• Santiago Marqués-González,
• Simon J. Higgins,
• Richard J. Nichols,
• Paul J. Low and
• Pilar Cea

Beilstein J. Nanotechnol. 2015, 6, 1145–1157, doi:10.3762/bjnano.6.116

• Monolayer Langmuir–Blodgett (LB) films of 1,4-bis(pyridin-4-ylethynyl)benzene (1) together with the “STM touch-to-contact” method have been used to study the nature of metal–monolayer–metal junctions in which the pyridyl group provides the contact at both molecule–surface interfaces. Surface pressure vs

• -aggregates. Scanning tunneling microscopy (STM), in particular the “STM touch-to-contact” method, was used to determine the electrical properties of LB films of 1. From these STM studies symmetrical I–V curves were obtained. A junction conductance of 5.17 × 10−5 G0 results from the analysis of the

• molecules within the LB film do not strongly influence the molecule conductance. The results presented here complement earlier studies of single molecule conductance of 1 using STM-BJ methods, and support the growing evidence that the pyridyl group is an efficient and effective anchoring group in sandwiched

Closed-loop conductance scanning tunneling spectroscopy: demonstrating the equivalence to the open-loop alternative

• Chris Hellenthal,
• Kai Sotthewes,
• Martin H. Siekman,
• E. Stefan Kooij and
• Harold J. W. Zandvliet

Beilstein J. Nanotechnol. 2015, 6, 1116–1124, doi:10.3762/bjnano.6.113

• charge; scanning tunneling spectroscopy (STS); tunneling barrier; work function; z(V); Introduction Although the scanning tunneling microscope (STM) has been used for the topographical imaging of conductive samples since the early 1980s [1], recent times have seen an increasing interest in the

• fact that the method can be applied by using z(V) spectroscopy means that it can also be used with STM devices that can only measure in closed-loop mode. Model An often used expression for the tunneling current was introduced by Simmons in 1963 [18] and is given as Here I is the tunneling current, ρ

• ) curve. All curves have been normalized to have the same starting point of roughly 2.2 nA at z0 = 0.6 nm. This value for z0 was estimated based on previous STM measurements [17] and will be used for all following analysis. While there is always a certain margin of error in estimating z0, changing this

Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons

• Kai Braun,
• Xiao Wang,
• Andreas M. Kern,
• Hilmar Adler,
• Heiko Peisert,
• Thomas Chassé,
• Dai Zhang and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2015, 6, 1100–1106, doi:10.3762/bjnano.6.111

• -field optical microscopy; tip-enhanced Raman spectroscopy; Introduction The emission of photons from the gap of a scanning tunneling microscope (STM) has been a focus of interest for more than twenty years [1][2] and has been used for acquiring spectroscopic information with ultra-high spatial

• of molecules enclosed in a laser-pumped tunneling junction of a STM. For efficient excitation and collection of photons the junction was centered in the focus of a parabolic mirror used in place of the objective lens in a confocal microscope [20][21][22][23]. The experimental apparatus and conditions

Graphene on SiC(0001) inspected by dynamic atomic force microscopy at room temperature

• Mykola Telychko,
• Jan Berger,
• Zsolt Majzik,
• Pavel Jelínek and
• Martin Švec

Beilstein J. Nanotechnol. 2015, 6, 901–906, doi:10.3762/bjnano.6.93

• accompanied by any out-of-plane relaxations of carbon atoms. Keywords: AFM; electron scattering; graphene; SiC; STM; Introduction Graphene epitaxially grown on a substrate differs in many aspects from free-standing graphene or graphene exfoliated onto insulating surfaces. The influence of the substrate

• of graphene grown on SiC substrate is a crucial factor for device construction. In this respect structural properties of graphene were extensively studied by atomic force microscopy (AFM) [7][8][9] and scanning tunneling microscopy (STM) [10][11][12]. STM measurements of single-layer (SLG) as well as

• bi-layer graphene (BLG) grown epitaxially on 6H- or 4H-SiC(0001) show a characteristic 6× 6 quasi-periodic corrugation (q-6 hereafter) [3][13][14][15]. It has not been clarified yet whether STM contrast on this surface has electronic or topographic origin. There is a lack of knowledge about the real

Stick–slip behaviour on Au(111) with adsorption of copper and sulfate

• Nikolay Podgaynyy,
• Sabine Wezisla,
• Christoph Molls,
• Shahid Iqbal and
• Helmut Baltruschat

Beilstein J. Nanotechnol. 2015, 6, 820–830, doi:10.3762/bjnano.6.85

• loads and also elucidate the conditions for atomic stick–slip. This system has been well studied in a large number of publications and therefore is a model system for fundamental studies. Many different methods have been used including STM [24][25], and also ex situ experiments such as LEED, AES and

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

• Lisa Michez,
• Kai Chen,
• Fabien Cheynis,
• Frédéric Leroy,
• Alain Ranguis,
• Haik Jamgotchian,
• Margrit Hanbücken and
• Laurence Masson

Beilstein J. Nanotechnol. 2015, 6, 777–784, doi:10.3762/bjnano.6.80

• Co layer exhibits an enhanced magnetization, strongly suggesting a ferromagnetic ordering with an in-plane easy axis of magnetization, which is perpendicular to the Co nanolines. Keywords: nanomagnetism; one-dimensional nanostructures; scanning tunneling microscopy (STM); self-organization; X-ray

• can be viewed in the STM image presented in Figure 1a, the Si NRs are parallel to the atomically dense rows of Ag(110) and have been shown to display a 2× periodicity along their edges (2 ∙ ≈ 0.6 nm) [23]. These NRs, denoted hereafter as single NRs, are composed of two rows of round protrusions [24

• ]. We note that these protrusions are too large to represent individual atoms. We have recently shown that neither STM nor non-contact atomic force microscopy (nc-AFM) probes can straightforwardly resolve the inner atomic structure of the Si NRs [25]. All NRs, varying only in length, present the same

A versatile strategy towards non-covalent functionalization of graphene by surface-confined supramolecular self-assembly of Janus tectons

• Ping Du,
• David Bléger,
• Fabrice Charra,
• Vincent Bouchiat,
• David Kreher,
• Fabrice Mathevet and
• André-Jean Attias

Beilstein J. Nanotechnol. 2015, 6, 632–639, doi:10.3762/bjnano.6.64

• -assembled on HOPG (Figure 2). The surface-confined molecular self-assemblies were characterized by scanning tunneling microscopy (STM) at the liquid–solid interface. As expected, they form non-covalent, surface self-assembled dimers, supramolecular linear polymers, and 2D networks. The versatility of the

• ]dithiaparacyclophane unit. The lower deck of this two-story linker is end-capped with two molecular clips in order to form the pedestal (A face), while a functional molecule, namely a distyrylbenzene fluorophore (highlighted in blue), forms the upper level (B face). STM studies at the liquid–HOPG interface

• and JAs were investigated by STM at the liquid–HOPG interface, at room temperature (Figure 6). First, it is obvious that all the probed Janus building blocks spontaneously self-assemble into 2D networks on HOPG. More surprisingly, they form periodic lattices with the same parameters within the typical

Entropy effects in the collective dynamic behavior of alkyl monolayers tethered to Si(111)

• Christian Godet

Beilstein J. Nanotechnol. 2015, 6, 583–594, doi:10.3762/bjnano.6.60

• relaxation peak intensities, relaxation mechanisms B1 and B2 will be, respectively, attributed to acid end-group dipoles and to gauche defect configurations. Results As reported previously [32], several techniques were used to obtain complementary information on the conformal coverage (STM, AFM), OML

Chains of carbon atoms: A vision or a new nanomaterial?

• Florian Banhart

Beilstein J. Nanotechnol. 2015, 6, 559–569, doi:10.3762/bjnano.6.58

• STM [42]. Oligoynes functionalized with anchor groups have been contacted by an STM tip, in part in solution. However, it is unclear whether individual monoatomic chains without side-links to other molecules have been present between the anchors and served as conductivity-limiting molecular junctions

In situ scanning tunneling microscopy study of Ca-modified rutile TiO₂(110) in bulk water

• Giulia Serrano,
• Beatrice Bonanni,
• Tomasz Kosmala,
• Marco Di Giovannantonio,
• Ulrike Diebold,
• Klaus Wandelt and
• Claudio Goletti

Beilstein J. Nanotechnol. 2015, 6, 438–443, doi:10.3762/bjnano.6.44

• Abstract Despite the rising technological interest in the use of calcium-modified TiO2 surfaces in biomedical implants, the Ca/TiO2 interface has not been studied in an aqueous environment. This investigation is the first report on the use of in situ scanning tunneling microscopy (STM) to study calcium

• impurity on the TiO2 bulk. In situ STM images of the surface in bulk water exhibit one-dimensional rows of segregated calcium regularly aligned with the [001] crystal direction. The in situ-characterized morphology and structure of this Ca-modified TiO2 surface are discussed and compared with UHV-STM

• ) structure has been proposed for the resulting Ca overlayer based on low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) measurements [1]. Segregation has been reported to produce an additional, differently ordered Ca layer, namely a p(3 × 1) structure [2][3][4]. More controlled

Synthesis, characterization, monolayer assembly and 2D lanthanide coordination of a linear terphenyl-di(propiolonitrile) linker on Ag(111)

• Zhi Chen,
• Svetlana Klyatskaya,
• José I. Urgel,
• David Écija,
• Olaf Fuhr,
• Willi Auwärter,
• Johannes V. Barth and
• Mario Ruben

Beilstein J. Nanotechnol. 2015, 6, 327–335, doi:10.3762/bjnano.6.31

• ; molecular self-assembly; organic monolayers; single crystal X-ray diffraction analysis; UHV-STM; Introduction The drive towards miniaturization of modern electronics has led to a growing interest in the development of memory units that can satisfy the ever-growing demand for information storage. In this

• single crystal X-ray diffraction analysis (XRD) along with other standard techniques (Supporting Information File 1). The results of the surface-confined, molecular self-assembly and the lanthanide coordination reaction were analysed by using low-temperature scanning tunnelling microscopy (STM). The STM

• the respect to the substrate within a given domain are present. The high-resolution STM topograph depicted in Figure 4a clearly indicates that the monolayer pattern is determined by non-covalent interactions between adjacent linkers, in particular electrostatic interactions [43][47][53]. The packing

Boosting the local anodic oxidation of silicon through carbon nanofiber atomic force microscopy probes

• Gemma Rius,
• Matteo Lorenzoni,
• Soichiro Matsui,
• Masaki Tanemura and
• Francesc Perez-Murano

Beilstein J. Nanotechnol. 2015, 6, 215–222, doi:10.3762/bjnano.6.20

• capability of in situ inspection, which provides additional control over the fabrication process including pattern placement [2]. SPL can be performed in a wide variety of instrument configurations and operation modes, such as in scanning tunneling microscopy (STM) or atomic force microscope (AFM). Based on

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

• Toma Susi,
• Thomas Pichler and
• Paola Ayala

Beilstein J. Nanotechnol. 2015, 6, 177–192, doi:10.3762/bjnano.6.17

• in their properties or in the distribution of dopants poses additional challenges for characterization. Furthermore, although local methods such as scanning tunneling microscopy (STM) [24][25] and transmission electron microscopy based electron energy loss spectroscopy (TEM/EELS) [23][26] can these

• double-walled carbon nanotubes, and for N-MWCNTs and N-graphene restrict ourselves to summarize studies in which synchrotron radiation or an additional complementary technique (such as STM, EELS or X-ray absorption spectroscopy) was used for probing the doping. Table 2 contains our survey, with both the

• samples where “pyridinic” binding energies are present [164], the 1NV was recently directly observed by STM in ion-implanted graphite [144]; see also [129] for a tentative identification of the 3NV in plasma-treated graphene. Thus it seems the exact atomic configuration of the sites responsible for these

Morphology, structural properties and reducibility of size-selected CeO_2−x nanoparticle films

• Maria Chiara Spadaro,
• Sergio D’Addato,
• Gabriele Gasperi,
• Francesco Benedetti,
• Paola Luches,
• Vincenzo Grillo,
• Giovanni Bertoni and
• Sergio Valeri

Beilstein J. Nanotechnol. 2015, 6, 60–67, doi:10.3762/bjnano.6.7

• 0.19 nm. The images were subsequently elaborated by using the STEM_CELL software [19]. Concerning the ultra-thin films we evaluated the morphology with in situ STM measurements by using an OMICRON room temperature SPM. The STM images have been processed by using the Image SXM software [20]. A second

• UHV apparatus was used to grow both epitaxial and non-epitaxial cerium oxide ultrathin films for comparison. The system is equipped with facilities for substrate preparation, film growth, in situ XPS, and scanning tunnelling microscopy (STM) analysis. The substrate used for film growth was a Pt(111

• treatments were performed under an oxygen partial pressure of pO2 = 1·10−7 mbar. XPS measurements were performed using an Al Kα X-ray source and a hemispherical electron analyzer. The STM was operated at room temperature in constant current mode, by using electrochemically etched tungsten tips, degassed by

Si/Ge intermixing during Ge Stranski–Krastanov growth

• Alain Portavoce,
• Khalid Hoummada,
• Antoine Ronda,
• Dominique Mangelinck and
• Isabelle Berbezier

Beilstein J. Nanotechnol. 2014, 5, 2374–2382, doi:10.3762/bjnano.5.246

• characterization techniques such as atomic force microscopy (AFM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), as well as photoluminescence spectroscopy (PL). Consequently, the control of the Ge island shape and density, as well as the control of Ge

Advanced atomic force microscopy techniques II

• Thilo Glatzel,
• Ricardo Garcia and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2014, 5, 2326–2327, doi:10.3762/bjnano.5.241

• invention of the scanning tunneling microscope (STM) in 1982 [1][2][3] and of the atomic force microscope (AFM) in 1986 [4]. These tools opened a huge field of nanoscale studies, from metal surfaces and clusters, molecular structures, insulators to liquid and electrochemical environments and even allowed

• growth of metal-organic frameworks have been created and analyzed by a nanografting technique by using an AFM as a structuring tool [10]. The effect of Cu intercalation at the interface of self-assembled monolayers and a Au(111)/mica substrate was analyzed by STM [11] as well as the growth behavior of

Spectroscopic mapping and selective electronic tuning of molecular orbitals in phosphorescent organometallic complexes – a new strategy for OLED materials

• Pascal R. Ewen,
• Jan Sanning,
• Tobias Koch,
• Nikos L. Doltsinis,
• Cristian A. Strassert and
• Daniel Wegner

Beilstein J. Nanotechnol. 2014, 5, 2248–2258, doi:10.3762/bjnano.5.234

• such as organic light-emitting diodes requires fundamental knowledge about the structural and electronic properties of the employed molecules as well as their interactions with neighboring molecules or interfaces. We show that highly resolved scanning tunneling microscopy (STM) and spectroscopy (STS

• spectra display the average of distributed MO levels due to a lack of spatial resolution. This has led to controversies as to how the MO levels should be deduced from the spectra [9][10]. In this context, the combined power of atomic and high energy resolution in scanning tunneling microscopy (STM) and

• the relevant frontier orbitals [11][12][13][14][15]. Several studies have performed STM and STS on organometallic compounds, mainly on porphyrins and phthalocyanines [16][17][18][19][20][21][22]. Considering this general success, it is surprising that phosphorescent complexes have barely been

UHV deposition and characterization of a mononuclear iron(III) β-diketonate complex on Au(111)

• Irene Cimatti,
• Silviya Ninova,
• Valeria Lanzilotto,
• Luigi Malavolti,
• Luca Rigamonti,
• Brunetto Cortigiani,
• Matteo Mannini,
• Elena Magnano,
• Federica Bondino,
• Federico Totti,
• Andrea Cornia and
• Roberta Sessoli

Beilstein J. Nanotechnol. 2014, 5, 2139–2148, doi:10.3762/bjnano.5.223

• , Italy 10.3762/bjnano.5.223 Abstract The adsorption of the sterically hindered β-diketonate complex Fe(dpm)3, where Hdpm = dipivaloylmethane, on Au(111) was investigated by ultraviolet photoelectron spectroscopy (UPS) and scanning tunnelling microscopy (STM). The high volatility of the molecule limited

• the growth of the film to a few monolayers. While UPS evidenced the presence of the β-diketonate ligands on the surface, the integrity of the molecule on the surface could not be assessed. The low temperature STM images were more informative and at submonolayer coverage they showed the presence of

• ) in octahedral environment were observed. Keywords: Au(111); β-diketonate complexes; DFT; STM; thin films; UPS; XMCD; XPS; Introduction A renewed interest in mononuclear metal complexes has recently arisen due to the observation that systems of this class can behave as single molecule magnets (SMMs

Carbon nano-onions (multi-layer fullerenes): chemistry and applications

• Juergen Bartelmess and
• Silvia Giordani

Beilstein J. Nanotechnol. 2014, 5, 1980–1998, doi:10.3762/bjnano.5.207

• , transient absorption studies of covalently functionalized CNOs yielded evidence for a strong difference of the absorption coefficients in the ground and excited state, which gives further rise to a possible application of this CNO material in optical limiting [25]. Molecular junctions in STM In another

• recent report, the groups of Plonska-Brzezinska and Echegoyen prepared sulfide-terminated CNO derivatives, which can be used as molecular junctions in scanning tunneling microscopy (STM) [83]. This enabled the authors to study the conductivity of CNOs and compare their properties with comparable

Patterning a hydrogen-bonded molecular monolayer with a hand-controlled scanning probe microscope

• Matthew F. B. Green,
• Taner Esat,
• Christian Wagner,
• Philipp Leinen,
• Alexander Grötsch,
• F. Stefan Tautz and
• Ruslan Temirov

Beilstein J. Nanotechnol. 2014, 5, 1926–1932, doi:10.3762/bjnano.5.203

• the potential energy surface that governs the interaction behaviour of the manipulated nanoscale object(s) is largely unknown. Keywords: atomic force microscopy (AFM); scanning tunneling microscopy (STM); single-molecule manipulation; 3,4,9,10-perylene tetracarboxylic acid dianhydride (PTCDA

• voltage pulses of 3–6 V (applied to the sample) and by crashing 10–30 Å deep into the clean Ag(111) surface whilst simultaneously applying a voltage of 0.1–1 V. The cleanness of the tip was validated by STM imaging of the former lowest unoccupied molecular orbital (LUMO) of PTCDA [10] and spectroscopy of

• the Ag(111) surface state. All PTCDA images shown were made with STM at I = 0.1 nA and with an applied bias voltage of V = −0.34 V that facilitates the intramolecular resolution corresponding to the LUMO. All of the reported experiments were performed in situ under ultra high vacuum conditions. The

Probing the electronic transport on the reconstructed Au/Ge(001) surface

• Franciszek Krok,
• Mark R. Kaspers,
• Alexander M. Bernhart,
• Marek Nikiel,
• Benedykt R. Jany,
• Paulina Indyka,
• Mateusz Wojtaszek,
• Rolf Möller and
• Christian A. Bobisch

Beilstein J. Nanotechnol. 2014, 5, 1463–1471, doi:10.3762/bjnano.5.159

• transport channel for electrons. Keywords: Au on Ge(001); electronic transport; multi probe STM; scanning tunnelling potentiometry; Introduction Structures consisting of single atoms represent the lower spatial limit for electronic circuits. On such a small scale, the electronic structure is dominated by

• (001) surface exhibits a two dimensional conductance channel on a micrometre-scale averaging across several Au-reconstructed 1D domains [10]. Scanning tunnelling microscopy (STM) and various STM-based methods are excellent tools to study the topographic structure, the electronic structure, and electron

• while a lateral current was flowing through the Au/Ge(001) sample (see also the scheme in Figure 1a below). By using a multiprobe STM setup (Omicron Nanoprobe) individually controlled STM tips are used to establish well defined electric contacts to the reconstructed surface. We applied a voltage between