scholarly journals Study on Formation Process and Models of Linear Fe Cluster Structure on a Si(111)-7 × 7-CH3OH Surface

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1593
Author(s):  
Wenxin Li ◽  
Wanyu Ding ◽  
Dongying Ju ◽  
Ken-ichi Tanaka ◽  
Fumio Komori
Keyword(s):  
Formation Process ◽  
Surface Display ◽  
Cluster Structure ◽  
Scanning Tunneling ◽  
Magnetic Memory ◽  
Face Centered Cubic ◽  
Tunneling Microscopy ◽  
Height Measurement ◽  
Adsorption Sites ◽  
Spectrometer Data

STM results showed that Fe atoms were deposited on a Si(111)-7 × 7 reconstructed surface, which was saturated with CH3OH molecules. Fe atomic linear structure was composed of stable clusters and in-situ observed by the scanning tunneling microscopy (STM). The aim to improve its application of magnetic memory material, both formation process and models, has been explored in this paper. By combining surface images and mass spectrometer data, an intermediate layer model was established. In terms of thermal stability, the most favorable adsorption sites of CH3OH were further explored. After that, Fe atoms were deposited on the Si(111)-7 × 7-CH3OH surface, forming a linear cluster structure. On the one hand, a new Fe cluster model was put forward in this paper, which was established with height measurement and 3D surface display technology. This model is also affected by the evaporation temperature, which can be consistent with the atomic stacking pattern of face centered cubic structures. On the other hand, the slight height change suggested the stability of linear structures. Even in the condition of thin air introduction, Fe cluster showed a good performance, which suggested the possibility of magnetic memory application in the future. These investigations are believed to have, to a certain extent, increased the probability of forming Fe linear clusters on the surface of silicon substrate, especially according to the models and surface technology we adjusted.

Density fluctuations as door-opener for diffusion on crowded surfaces

Science ◽  
2019 ◽  
Vol 363 (6428) ◽  
pp. 715-718 ◽  
Author(s):  
Ann-Kathrin Henß ◽  
Sung Sakong ◽  
Philipp K. Messer ◽  
Joachim Wiechers ◽  
Rolf Schuster ◽  
...  
Keyword(s):  
High Speed ◽  
Density Functional ◽  
Local Density ◽  
Variable Temperature ◽  
Industrial Process ◽  
Density Fluctuations ◽  
Scanning Tunneling ◽  
Fast Diffusion ◽  
Tunneling Microscopy ◽  
Adsorption Sites

How particles can move on a catalyst surface that, under the conditions of an industrial process, is highly covered by adsorbates and where most adsorption sites are occupied has remained an open question. We have studied the diffusion of O atoms on a fully CO-covered Ru(0001) surface by means of high-speed/variable-temperature scanning tunneling microscopy combined with density functional theory calculations. Atomically resolved trajectories show a surprisingly fast diffusion of the O atoms, almost as fast as on the clean surface. This finding can be explained by a “door-opening” mechanism in which local density fluctuations in the CO layer intermittently create diffusion pathways on which the O atoms can move with low activation energy.

STM STUDIES OF COEXISTING S-INDUCED STRUCTURES ON Cu(110)

1994 ◽  
Vol 01 (04) ◽  
pp. 705-708 ◽  
Author(s):  
T.M. PARKER ◽  
N.G. CONDON ◽  
R. LINDSAY ◽  
G. THORNTON ◽  
F.M. LEIBSLE
Keyword(s):  
Scanning Tunneling Microscopy ◽  
S Phase ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
New Model ◽  
Adsorption Sites ◽  
Underlying Substrate

Scanning tunneling microscopy (STM) has been used to study the "c(2×2)" and p(5×2) sulphur-induced structures on Cu(110). Images have been obtained of the "c(2×2)" S /p(5×2)S codomain. Using previous results which show that the sulphur related features in "c(2×2)"S domains are above twofold hollow sites,1 we are able to derive, with respect to the underlying substrate, the sulphur adsorption sites for the p(5×2)S phase. We are therefore able to propose a new model for the p(5×2)S phase and speculate as to the structure of the c(8×2)S phase which occurs at higher coverages. These results show the conflict between the accommodation of further S adsorption at higher coverages and the tendency of the S-adatoms to occupy the twofold hollow sites.

Understanding Metal Oxide Surfaces at the Atomic Scale: STM Investigations of Bulk-defect Dependent Surface Processes

2000 ◽  
Vol 654 ◽  
Author(s):  
Ulrike Diebold
Keyword(s):  
Oxygen Vacancies ◽  
Science Studies ◽  
Elevated Temperatures ◽  
Surface Defects ◽  
Surface Reactivity ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Oxide Surface ◽  
Tunneling Microscopy ◽  
Adsorption Sites

AbstractSurface defects are important in oxide surface chemistry, because they change not only the surface geometric structure, but also affect the local electronic structure. Scanning Tunneling Microscopy (STM) images with atomic-scale resolution, in combination with area-averaging surface spectroscopies, is an ideal tool to study local surface defects and their relationship to surface reactivity. We report STM results onTiO2(110) surfaces which show the surprising influence of bulk defects on surface properties. Thereduced crystals used in this and other surface science studies contain Ti interstitials and oxygen vacancies. Re-oxidation at elevated temperatures results in the growth of additional TiO2 layers with Ti coming from the bulk of the crystal and O from the gas phase. This often result in partially incomplete surface structures with many undercoordinated atoms. The esorption behavior of elemental S, dosed at room temperature, depends on the reduction state of the sample. This is explained by a mechanism where desorption froma weaklybound precursor state competes with the availability of new adsorption sites in the form of oxygen vacancies which migrate from the bulk to the surface.

scholarly journals Synthesis of monodispersed model catalysts using softlanding cluster deposition

2002 ◽  
Vol 74 (9) ◽  
pp. 1527-1535 ◽  
Author(s):  
Stéphane Abbet ◽  
Ken Judai ◽  
Laurent Klinger ◽  
Ueli Heiz
Keyword(s):  
Chemical Properties ◽  
Model Systems ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Adsorption Sites ◽  
Single Atoms ◽  
Carbonyl Formation ◽  
Experimental Findings ◽  
Defect Densities ◽  
Single Size

In nanocatalysis, clusters deposited on solid, well-defined surfaces play an important role. For the detection of size effects it is, however, important to prepare samples consisting of deposited clusters of a single size, as their chemical properties change with the exact number of atoms in the cluster. In this paper, the experimental tools are presented to prepare such model systems. The existence of monodispersed clusters is confirmed by various experimental findings. First, the carbonyl formation of deposited Nin clusters shows no change in the nuclearity when comparing the size of the deposited clusters with one of the formed carbonyls. Second, scanning tunneling microscopy (STM) studies show that fragmentation of Sin clusters upon deposition can be excluded. In addition, the adsorption behavior of CO on deposited Pd atoms points to the existence of single atoms on the surface. Furthermore, CO oxidation results on Aun clusters confirm the existence of monodispersed clusters trapped on well-defined adsorption sites. Finally, we use Monte-Carlo simulations to define the range of clusters and defect densities, for which monodispersed clusters can be expected.

SITE-SPECIFIC SURFACE CHEMISTRY OF GaAs (001)

2000 ◽  
Vol 07 (05n06) ◽  
pp. 625-629 ◽  
Author(s):  
L. LI
Keyword(s):  
Surface Chemistry ◽  
Carbon Doping ◽  
Scanning Tunneling ◽  
Organic Chemical ◽  
Semiconductor Surface ◽  
Adsorbed Hydrogen ◽  
Tunneling Microscopy ◽  
Etch Pits ◽  
Site Specific ◽  
Adsorption Sites

In this article, we summarize our studies of the surface chemistry of gallium arsenide as it pertains to the metal organic chemical vapor deposition of compound semiconductors. It has been found by scanning tunneling microscopy and vibrational spectroscopy that the adsorption of reactant molecules on reconstruted GaAs (001) surfaces is "site-specific." The adsorption sites on the semiconductor surface are revealed by the vibrational spectrum of adsorbed hydrogen. Studies of arsine adsorption have shown that it dissociatively adsorbs only on gallium sites and transfers hydrogen to the neighboring As atom. Studies of carbon doping with carbon tetrachloride have shown that adsorbed chlorine attacks the exposed gallium and generates volatile GaCl x species. The site-specific nature of this reaction leads to a dramatic change in the film morphology, with the formation of etch pits primarily distributed along the step edges.

Formation Process of a Cu−Zn Surface Alloy on Cu(111) Investigated by Scanning Tunneling Microscopy

2002 ◽  
Vol 106 (31) ◽  
pp. 7627-7633 ◽  
Author(s):  
Miki Sano ◽  
Tomoyuki Adaniya ◽  
Tadahiro Fujitani ◽  
Junji Nakamura
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Formation Process ◽  
Surface Alloy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy

STM observation of formation process of carbon nanotube from 6H-SiC (000-1)

2005 ◽  
Vol 901 ◽  
Author(s):  
Takahiro Maruyama ◽  
Yasuyuki Kawamura ◽  
Hyungjin Bang ◽  
Naomi Fujita ◽  
Tomoyuki Shiraiwa ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Scanning Tunneling Microscopy ◽  
Formation Process ◽  
Ultrahigh Vacuum ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Carbon Networks ◽  
Thermally Treated

AbstractFormation process of nanosized cap structures on a thermally treated 6H-SiC(000-1) substrate was investigated using atomic-resolution ultrahigh-vacuum scanning tunneling microscopy (UHV-STM). After formation of clusters of carobon particles 1-2 nanometer in diameter at 1150°C, these nanoparticles merged, forming nanosized cap structures. Hexagonal carbon networks, partly composed of pentagons, were clearly observed on the surface of the cap structures for a sample annealed above 1200°C. A model for the formation of carbon nanocaps on 6H-SiC(000-1) was proposed.

High-resolution TEM of C60 thin films

1992 ◽  
Vol 50 (1) ◽  
pp. 108-109
Author(s):  
W. Krakow ◽  
N.M. Rivera ◽  
R.A. Roy ◽  
J.J. Cuomo
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Room Temperature ◽  
Bulk Material ◽  
Hexagonal Phase ◽  
Hexagonal Structure ◽  
Scanning Tunneling ◽  
Bravais Lattice ◽  
Face Centered Cubic ◽  
Tunneling Microscopy

The ability to fabricate buckminsterfullerenes, C60 molecules, in reasonably large quantities has made possible studies of the structural properties of this form of carbon when it is in a crystalline state. At room temperature, x-ray diffraction from three-dimensional bulk C60 crystals shows that the molecules are centered on sites of a face-centered-cubic Bravais lattice, A∘ = 14.2Å. Somewhat earlier in time, a study of C60/C70 bulk material using electron diffraction and high resolution electron microscopy has revealed a hexagonal phase. It is now believed that this phase is a simple cubic structure rather than a hexagonal structure. Since it is reasonable to expect that highly ordered C60 thin films will have superior properties to bulk material, several studies have been undertaken to understand the early stages of C60 thin film growth. Monolayer growth on GaAs has been studied by scanning tunneling microscopy., and on mica at room temperature using helium scattering. Along similar lines we have grown thin films of C60 molecules on mica and NaCl and characterized the crystallinity and local structural arrangements. Here we present some of our results of the electron microscope examination of these materials.

Geometric and Electronic Structure of Fullerene Film Growth as a Function of Coverage

1994 ◽  
Vol 359 ◽  
Author(s):  
B. Reihl
Keyword(s):  
Electronic Structure ◽  
Low Temperatures ◽  
Film Growth ◽  
Theoretical Calculations ◽  
Scanning Tunneling ◽  
Island Growth ◽  
Tunneling Microscopy ◽  
Adsorption Sites ◽  
Adsorbed Monolayer ◽  
Inverse Photoemission

ABSTRACTWe have employed scanning tunneling microscopy at room and low temperature, i.e. 300, 50, and 5 K, to study the epitaxy and growth of fullerene films on the noble-metal surfaces Ag(110) and Au(110). Initial island growth occurs on terrace sites away from substrate step edges. Particularly at low temperatures where the rotational and vibrational movements of the fullerene molecules are frozen in, different intra-molecular topographic patterns become visible in ordered films, which are characteristic of particular adsorption sites. Complementary tunneling spectroscopy and direct and inverse photoemission measurements reveal distinct differences between the first adsorbed monolayer and additional fullerene layers indicating differences in bonding and charge transfer. Our results are compared to theoretical calculations.

Sign in / Sign up

Export Citation Format

Share Document