Probing Surface Roughness and Porosity through Adsorption of Wetting Layers

1994 ◽  
Vol 366 ◽  
Author(s):  
J. Krim ◽  
V. Panella
Keyword(s):  
Surface Tension ◽  
Adsorption Isotherms ◽  
Capillary Condensation ◽  
Scanning Tunneling ◽  
Fractal Nature ◽  
Tunneling Microscopy ◽  
Gold Surfaces ◽  
X Ray ◽  
Adsorption Data ◽  
The Impact

ABSTRACTWe have employed a quartz microbalance technique to record adsorption isotherms on silver and gold surfaces whose roughness has also been characterized by x-ray reflectivity or scanning tunneling microscopy. We observe strikingly different behavior for two different liquid adsorbates (oxygen and nitrogen), and attribute this to a difference in their surface tension. Our results demonstrate the impact that capillary condensation phenomena can have on the interpretation of adsorption data, particularly with regards to the fractal nature of the substrate. Valuable information on surface morphology can nonetheless be obtained from adsorption isotherms, if combined with alternate experimental techniques.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

scholarly journals Templated quasicrystalline ordering of single elements and molecules

2014 ◽  
Vol 70 (a1) ◽  
pp. C81-C81
Author(s):  
H. R. Sharma ◽  
J. A. Smerdon ◽  
K. Nozawa ◽  
K. M. Young ◽  
T. P. Yadav ◽  
...  
Keyword(s):  
Substrate Surface ◽  
Chemical Properties ◽  
Scanning Tunneling ◽  
Three Dimension ◽  
Tunneling Microscopy ◽  
Quantum Size ◽  
Adsorption Energies ◽  
Molecular Layers ◽  
Physical And Chemical ◽  
The Impact

We have used quasicrystals as templates for the exploration of new epitaxial phenomena. Several interesting results have been observed in the growth on surfaces of the common Al-based quasicrystals [1]. These include pseudomorphic monolayers, quasiperiodically modulated multilayer structures, and fivefold-twinned islands with magic heights influenced by quantum size effects [1]. Here we present our recent works on the growth of various elements and molecules on a new substrate, icosahedral (i) Ag-In-Yb quasicrystal, which have resulted in various epitaxial phenomena not observed previously. The growth of Pb on the five-fold surface of i-Ag-In-Yb yields a film which possesses quasicrystalline ordering in three-dimension [2]. Using scanning tunneling microscopy (STM) and DFT calculations of adsorption energies, we find that lead atoms occupy the positions of atoms in the rhombic triacontahedral (RTH) cluster, the building block of the substrate, and thus grow in layers with different heights and adsorption energies. The adlayer–adlayer interaction is crucial for stabilizing the epitaxial quasicrystalline structure. We will also present the first example of quasicrystalline molecular layers. Pentacene adsorbs at tenfold-symmetric sites of Yb atoms around surface-bisected RTH clusters, yielding quasicrystalline order [3]. Similarly, C-60 growth on the five-fold surface of i-Al-Cu-Fe at elevated temperature produces quasicrystalline layer, where the growth is mediated by Fe atoms on the substrate surface [3]. The finding of quasicrystalline thin films of single elements and molecules opens an avenue for further investigation of the impact of the aperiodic atomic order over periodic order on the physical and chemical properties of materials.

scholarly journals Interface morphology of a Cr(001)/Fe(001) superlattice determined by scanning tunneling microscopy and x-ray diffraction: A comparison

2001 ◽  
Vol 89 (1) ◽  
pp. 181-187 ◽  
Author(s):  
C. M. Schmidt ◽  
D. E. Bürgler ◽  
D. M. Schaller ◽  
F. Meisinger ◽  
H.-J. Güntherodt ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Scanning Tunneling ◽  
Interface Morphology ◽  
X Ray Diffraction ◽  
Tunneling Microscopy ◽  
X Ray

scholarly journals Structural determination of the Si(111) √3×√3-Bi surface by x-ray standing waves and scanning tunneling microscopy

1994 ◽  
Vol 50 (16) ◽  
pp. 12246-12249 ◽  
Author(s):  
J. C. Woicik ◽  
G. E. Franklin ◽  
Chien Liu ◽  
R. E. Martinez ◽  
I.-S. Hwong ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Standing Waves ◽  
Scanning Tunneling ◽  
Structural Determination ◽  
Tunneling Microscopy ◽  
X Ray

Nb-H Thin Films: On Phase Transformation Kinetics

2017 ◽  
Vol 371 ◽  
pp. 160-165
Author(s):  
Vladimir Burlaka ◽  
Kai Nörthemann ◽  
Astrid Pundt
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Scanning Tunneling ◽  
State Change ◽  
Transformation Kinetics ◽  
Tunneling Microscopy ◽  
Fast Phase ◽  
Phase Transformation Kinetics ◽  
Local Lattice ◽  
The Impact

It was recently shown that phases forming in thin films undergo a coherency state change depending on the film thickness. For Nb-H thin films, the coherency state was reported to change at about 38 nm. In this study the impact of the coherency state on the phase transformation kinetics is investigated for Nb films of two different film thicknesses (25 nm and 80 nm), below and above the state change thickness. The phase transformation in thin metal-hydrogen films can be studied by surface topography analyses via scanning tunneling microscopy (STM) because of the strong local lattice expansion of the hydride precipitates. STM on Nb-H reveals fast phase transformation kinetics for the 25 nm Nb-film, and much slower kinetics for the 80 nm film. This is suggested to be related to the change in the coherency between the Nb-matrix and the hydride precipitates.

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