Self-Assembly of Nickel Icosahedrons and Truncated Octahedral Nanocrystals on a SrTiO3 (111) Support

Microscopy ◽  
2020 ◽  
Author(s):  
Atif Rasheed
Keyword(s):  
Self Assembly ◽  
Scanning Tunneling Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Work Of Adhesion ◽  
Scanning Tunneling ◽  
Equilibrium Crystal Shapes ◽  
Crystal Properties ◽  
Energy Ratios ◽  
Octahedral Nanocrystals

Abstract Nickel nanocrystals have received much attention for their ferromagnetic properties. The crystal properties are strongly dependent on their facets and therefore detailed study of their morphology, facets and orientation is critical for magnetic applications. In this work, equilibrium crystal shapes of self-assembled nickel nanocrystals on the (111) termination of strontium titanate (SrTiO3) at room temperature and under ultra-high vacuum (UHV) conditions have been investigated using scanning tunneling microscope (STM). SrTiO3 (111) substrate was sputtered (0.5 keV, 2.5 µA, 10 min) and annealed (900 °C, 1 h) under UHV conditions. Three different periodicities were observed: (2.21 ± 0.01) nm corresponding to (4 × 4) reconstruction, (3.31 ± 0.02) nm corresponding to (6 × 6) reconstruction, and (2.85 ± 0.05) nm, rotated at 30° with respect to (4 × 4) reconstruction, corresponding to (3√3 × 3√3)R30° reconstruction. Nickel (~1 ML) was deposited using an e-beam evaporator on the substrate preheated to 320 °C and the sample was post-annealed multiple times. Nickel took platonic shapes of supported icosahedron comprising of (111) facets and truncated octahedron comprising of (001) and (111) facets. Based on surface energy ratios of truncated octahedrons at equilibrium the work of adhesion was calculated to be (3.889 ± 0.167) J/m2.

scholarly journals Strain-Relief Patterns and Kagome Lattice in Self-Assembled C60 Thin Films Grown on Cd(0001)

2021 ◽  
Vol 22 (13) ◽  
pp. 6880
Author(s):  
Zilong Wang ◽  
Minlong Tao ◽  
Daxiao Yang ◽  
Zuo Li ◽  
Mingxia Shi ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Kagome Lattice ◽  
Tunneling Microscopy ◽  
Kagomé Lattice ◽  
Temperature Scanning ◽  
C60 Films

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

scholarly journals Au(100) as a Template for Pentacene Monolayer

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2393
Author(s):  
Artur Trembułowicz ◽  
Agata Sabik ◽  
Miłosz Grodzicki
Keyword(s):  
Self Assembly ◽  
Molecular Layer ◽  
High Vacuum ◽  
Gold Surface ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Height Difference ◽  
Characteristic Features ◽  
Reconstructed Surface

The surface of quasi-hexagonal reconstructed Au(100) is used as the template for monolayer pentacene (PEN) self-assembly. The system is characterized by means of scanning tunneling microscopy at room temperature and under an ultra-high vacuum. A new modulated pattern of molecules with long molecular axes (MA) arranged along hex stripes is found. The characteristic features of the hex reconstruction are preserved herein. The assembly with MA across the hex rows leads to an unmodulated structure, where the molecular layer does not recreate the buckled hex phase. The presence of the molecules partly lifts the reconstruction—i.e., the gold hex phase is transformed into a (1×1) phase. The arrangement of PEN on the gold (1×1) structure is the same as that of the surrounding molecular domain on the reconstructed surface. The apparent height difference between phases allows for the distinction of the state of the underlying gold surface.

scholarly journals A modular ultra-high vacuum millikelvin scanning tunneling microscope

2020 ◽  
Vol 91 (2) ◽  
pp. 023703 ◽  
Author(s):  
Dillon Wong ◽  
Sangjun Jeon ◽  
Kevin P. Nuckolls ◽  
Myungchul Oh ◽  
Simon C. J. Kingsley ◽  
...  
Keyword(s):  
Scanning Tunneling Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscope

A reliable compact ultra-high vacuum scanning tunneling microscope

Vacuum ◽  
1995 ◽  
Vol 46 (3) ◽  
pp. 219-222 ◽  
Author(s):  
IV Lyubinetsky ◽  
PV Mel'nik ◽  
NG Nakhodkin ◽  
AE Anisimov
Keyword(s):  
Scanning Tunneling Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscope

Low-temperature ultra-high-vacuum scanning tunneling microscope

1992 ◽  
Vol 42-44 ◽  
pp. 1621-1626 ◽  
Author(s):  
R. Gaisch ◽  
J.K. Gimzewski ◽  
B. Reihl ◽  
R.R. Schlittler ◽  
M. Tschudy ◽  
...  
Keyword(s):  
Low Temperature ◽  
Scanning Tunneling Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscope

Application of Scanning Tunneling Microscopy to the Study of Metals: Spectroscopy and Topography

1986 ◽  
Vol 77 ◽  
Author(s):  
R. C. Jaklevic ◽  
W. J. Kaiser
Keyword(s):  
Scanning Tunneling Microscope ◽  
Standard Sample ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Ordered Array ◽  
And Performance ◽  
Smooth Planes ◽  
Equal Height

ABSTRACTThe design and performance of a scanning tunneling microscope for use in the study of metal surfaces is described. The system was designed for ultra high vacuum together with standard sample cleaning and characterization techniques. The STM provides both topographic and spectroscopie information. Topographic images of well annealed Au(lll) show very smooth planes with single atomic steps. Corrugation on the (111) planes, which is expected from reconstruction models for this surface, is not seen. Other areas show monatomic steps in the form of an ordered array with a period corresponding to that derived from previous studies. A possible alternative reconstruction mechanism is suggested by these STM data. On the same surface are steeper sloped regions with multiple steps of equal height with wide facets. Spectroscopie first derivative data for Au and Pd show peaks which correspond to surface and bulk electronic states, for both filled and unfilled cases. The energy values of these states are compared directly with the results of other experimental methods. The use of combined topographic and spectroscopie mode for metals is anticipated.

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