Understanding the Contrast Mechanism in Scanning Tunneling Microscopy (STM) Images of an Intermixed Tetraphenylporphyrin Layer on Ag(111)

Langmuir ◽  
2008 ◽  
Vol 24 (5) ◽  
pp. 1897-1901 ◽  
Author(s):  
Karmen Comanici ◽  
Florian Buchner ◽  
Ken Flechtner ◽  
Thomas Lukasczyk ◽  
J. Michael Gottfried ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Contrast Mechanism ◽  
Stm Images

Scanning Tunneling Microscopy of Amorphous Carbon Films

1990 ◽  
Vol 48 (1) ◽  
pp. 318-319
Author(s):  
Mircea Fotino ◽  
D.C. Parks
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Amorphous Carbon ◽  
Carbon Films ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Amorphous Carbon Films ◽  
Image Optimization ◽  
Step Procedure ◽  
Stm Images

In the last few years scanning tunneling microscopy (STM) has made it possible and easily accessible to visualize surfaces of conducting specimens at the atomic scale. Such performance allows the detailed characterization of surface morphology in an increasing spectrum of applications in a wide variety of fields. Because the basic imaging process in STM differs fundamentally from its equivalent in other well-established microscopies, good understanding of the imaging mechanism in STM enables one to grasp the correct information content in STM images. It thus appears appropriate to explore by STM the structure of amorphous carbon films because they are used in many applications, in particular in the investigation of delicate biological specimens that may be altered through the preparation procedures.All STM images in the present study were obtained with the commercial instrument Nanoscope II (Digital Instruments, Inc., Santa Barbara, California). Since the importance of the scanning tip for image optimization and artifact reduction cannot be sufficiently emphasized, as stressed by early analyses of STM image formation, great attention has been directed toward adopting the most satisfactory tip geometry. The tips used here consisted either of mechanically sheared Pt/Ir wire (90:10, 0.010" diameter) or of etched W wire (0.030" diameter). The latter were eventually preferred after a two-step procedure for etching in NaOH was found to produce routinely tips with one or more short whiskers that are essentially rigid, uniform and sharp (Fig. 1) . Under these circumstances, atomic-resolution images of cleaved highly-ordered pyro-lytic graphite (HOPG) were reproducibly and readily attained as a standard criterion for easily recognizable and satisfactory performance (Fig. 2).

scholarly journals The Effect of Deposition Time on the Surface Coverage of Sublimation Deposited Solid-Phase Glycine and Proline Molecules Measured by Scanning Tunneling Microscopy

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 2962
Author(s):  
Young-Sang Youn
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Room Temperature ◽  
Deposition Time ◽  
Surface Coverage ◽  
Solid Phase ◽  
Scanning Tunneling ◽  
Adsorption Model ◽  
Tunneling Microscopy ◽  
Langmuir Adsorption ◽  
Stm Images

The effect of deposition time on the surface coverage of sublimation deposited solid-phase glycine and proline molecules onto a Ge(100) surface was studied at room temperature using scanning tunneling microscopy (STM). The STM images obtained at various coverages of glycine and proline adsorbed on the Ge(100) surface showed that (i) the adsorption rate for both molecules gradually decreased with increasing deposition time, obeying the Langmuir adsorption model, and (ii) the coverage of glycine on the Ge(100) surface is higher than that of proline under the same deposition conditions, which may be due to the differences in their molecular weight or molecular sticking probability.

Scanning Tunneling Microscopy Imaging of Defects in Layered Compounds

1990 ◽  
Vol 209 ◽  
Author(s):  
G. P. E. M. Van Bakell ◽  
J. Th. M. De Hosson ◽  
T. Hibma
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Structural Features ◽  
Layered Compounds ◽  
Scanning Tunneling ◽  
X Ray Diffraction ◽  
Tunneling Microscopy ◽  
Microscopy Imaging ◽  
X Ray ◽  
Sample Orientation ◽  
Stm Images

ABSTRACTStructural features of TiS2 were studied by scanning tunneling microscopy (STM) and single-crystal X-ray diffraction was applied as a complementary technique. STM images in air and at room temperature revealed, beside the trigonal symmetry of the lattice, several new features having this symmetry as well. We conclude that these features not only are to be described by structural defect phenomena which affect octahedral sites in the 1T-CdI2 structure but tetrahedral sites as well. Sample orientation determination by X-ray diffraction provides a unique relation between feature types and sites. A model is proposed in which displaced Ti atoms account for the observed features.

scholarly journals Thermal evolution of the morphology of Ni/Ge(111)-c(2 × 8) surface

2014 ◽  
Vol 32 (4) ◽  
pp. 641-647 ◽  
Author(s):  
Agnieszka Tomaszewska ◽  
Jhen-Hao Li ◽  
Xiao-Lan Huang ◽  
Tsu-Yi Fu
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Room Temperature ◽  
Thermal Evolution ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Nucleation Sites ◽  
Dual Polarity ◽  
Stm Images

AbstractThe thermal evolution of the interface formed by room temperature (RT) deposition of Ni atoms (coverage 0.1, 0.5, 1.2 ML) onto a Ge(111)-c(2 × 8) surface has been studied with the use of scanning tunneling microscopy (STM). Atomically resolved STM images revealed that, at RT, the boundaries between the different c(2 × 8) domains acted as nucleation sites for Ni atoms. After annealing the surface with deposited material at 473 to 673 K the formation of nano-sized islands of NixGey compounds was observed. In addition, the occurrence of ring-like structures was recorded. Based on the dual-polarity images the latter were assigned to Ni atoms adsorbed on Ge adatoms.

Atomic Structure of the Domain Walls of the Discommensurate Phases in Ge(111)/Ga

1998 ◽  
Vol 05 (01) ◽  
pp. 175-179 ◽  
Author(s):  
Zheng Gai ◽  
Bo Gao ◽  
Hang Ji ◽  
R. G. Zhao ◽  
W. S. Yang
Keyword(s):  
Domain Wall ◽  
Scanning Tunneling Microscopy ◽  
Atomic Structure ◽  
Domain Walls ◽  
Scanning Tunneling ◽  
Wall Structure ◽  
Tunneling Microscopy ◽  
Domain Wall Structure ◽  
Stm Images

We have studied the γ and β discommensurate phases of the Ge(111)/Ga system with scanning tunneling microscopy (STM). On the basis of the features of these phases known from our STM images as well as from previous papers, models of domain-wall structure of both phases have been proposed for further investigations.

Characterization of Epitaxial Fe on GaAs(110) by Scanning Tunneling Microscopy

1989 ◽  
Vol 151 ◽  
Author(s):  
R. A. Dragoset ◽  
P. N. First ◽  
Joseph A. Stroscio ◽  
D. T. Pierce ◽  
R. J. Celotta
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Lattice Mismatch ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Small Lattice ◽  
Low Coverage ◽  
Substrate Temperatures ◽  
Stm Images ◽  
Interesting System

ABSTRACTIron on GaAs(110) comprises an interesting system not only due to small lattice mismatch, 1.4%, but also because of the magnetic properties of the overlayer. In the present work, scanning tunneling microscopy (STM) was used to investigate bcc Fe films in the 0.1 Å to 20 Å thickness range, grown at 300 K and 450 K substrate temperatures. STM images show Volmer-Weber growth with the formation of 3-D Fe islands 20–30 Å in diameter for 0.1–1 Å deposition at 300 K, increasing to 40–50 Å for thicker films. Iron island sizes at low coverage and thin film roughness at higher coverages both show significant dependence upon growth temperature.

STRUCTURES AND DYNAMICS OF ENDOHEDRAL SCANDIUM METALLOFULLERENES

1996 ◽  
Vol 03 (01) ◽  
pp. 799-802 ◽  
Author(s):  
H. SHINOHARA ◽  
M. TANSHO ◽  
M. INAKUMA ◽  
Y. SAITO ◽  
H. SATO ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Scanning Tunneling Microscopy ◽  
High Performance ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Direct Imaging ◽  
Two Stage ◽  
Endohedral Metallofullerenes ◽  
Stm Images

The endohedral metallofullerenes, such as Sc@C 82, Sc 2@ C 84, and Sc 3@ C 82, have been purified and isolated by using two-stage high-performance liquid chromatography (HPLC). The ESR spectrum of the isolated Sc 3@ C 82 exhibits a perfectly symmetric 22 hyperfined splittings with an inherent linewidth of 0.77 Gauss at 220 K, which is consistent with a unique structure that three scandium atoms are encaged triangularly within the C3v isomer of C 82. In addition, we report the direct imaging of the isolated discandium fullerene ( Sc 2@ C 84) on silicon clean surfaces in an ultrahigh-vacuum environment by utilizing scanning tunneling microscopy (STM). The STM images reveal spherical Sc 2@ C 84 fullerenes, spaced 11.7 Å apart, stacked in close-packed arrays.

Nano-Scale Tribology Study of Organic Adlayer-Metal Interface Using Quartz Crystal Microbalance Combined With Scanning Tunneling Microscopy

2005 ◽  
Author(s):  
Sang M. Lee ◽  
M. Abdelmaksoud ◽  
J. Krim
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Frictional Heating ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Physical Interactions ◽  
Frequency Changes ◽  
Physical Phenomena ◽  
Stm Images

A quartz crystal microbalance combined with scanning tunneling microscopy (STM-QCM) was used to investigate the interactions between organic adlayers (C6H6 and C6H5I) on Cu surfaces and a metallic STM tip. STM images of C6H6 covered Cu surface improved when the QCM was simultaneously oscillated during the imaging. In contrast, STM images of C6H5I covered surfaces became noisy when the sample was oscillated. The two systems moreover exhibited frequency changes of opposite signs in response to STM tip contact, indicative of different physical phenomena at the surface. The dependence of the STM image quality and the frequency shift were interpreted in terms of the adsorbate-substrate chemical and physical interactions, and different levels of frictional heating at the interface.

Simulating Stm Images for the Gaas (110) Surface

1997 ◽  
Vol 492 ◽  
Author(s):  
James R. Chelikowsky ◽  
Hanchul Kim
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Ab Initio ◽  
Surface Structure ◽  
Gaas Surface ◽  
Scanning Tunneling ◽  
Semiconductor Surfaces ◽  
Tunneling Microscopy ◽  
Pseudopotential Calculations ◽  
Stm Image ◽  
Stm Images

ABSTRACTScanning tunneling microscopy (STM) is one of the most successful experimental tools for probing the structure of semiconductor surfaces. However, care must be taken in interpreting the images at the atomistic limit. Often a “naive” interpretation of the STM image can yield an incorrect surface structure. We illustrate this situation via ab initio pseudopotential calculations for the STM image of the (110) GaAs surface. We will compare theoretical STM images to experimental images for the relaxed surface and for a surface with an As vacancy.

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