PHOTOINDUCED PRODUCTS IN A C60 MONOLAYER ON ${\rm Si}(111) (\sqrt{3}\times \sqrt{3})\hbox{-}{\rm Ag}$: AN STM STUDY

Irradiation of ultraviolet-visible light onto a C 60 monolayer on [Formula: see text] resulted in a chemical reaction between adjacent C 60 molecules, as confirmed by scanning tunneling microscopy (STM) images. The major photoinduced products were double-bonded (two covalent C–C bonds between molecules) C 60 dimers and linear trimers. We also found single-bonded (single covalent bond between molecules) C 60 dimers and linear trimers, and two-dimensional C 60 oligomers as minor products. Observed atomic geometry of the nonbonding contact between a C 60 dimer (or a trimer) and a neighboring dimer (or a trimer), which are parallel to each other regarding their axes, is different from that reported between C 60 molecules in three-dimensional C 60 crystals, where there is no interaction with a substrate.

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Relaxation of Nanostructures on the Si(111)(7×7) Surface by High Temperature Scanning Tunneling Microscopy

Surface Review and Letters ◽

10.1142/s0218625x98001195 ◽

1998 ◽

Vol 05 (03n04) ◽

pp. 821-832 ◽

Cited By ~ 15

Author(s):

Ayahiko Ichimiya ◽

Yoriko Tanaka ◽

Kazuhiko Hayashi

Keyword(s):

Scanning Tunneling Microscopy ◽

Three Dimensional ◽

Thermal Relaxation ◽

Scanning Tunneling ◽

Two Dimensional ◽

Tunneling Microscopy ◽

Temperature Variable ◽

Long Lifetime ◽

Temperature Scanning ◽

Silicon Islands

Single silicon islands have been produced on the Si(111)(7 × 7) surface by a scanning tunneling microscope (STM) tip. Thermal relaxation of the isolated islands is observed by temperature variable scanning tunneling microscopy with strong tip effects. The sizes of islands depend on time t with a functional form of (t0-t)α. It is found that α≃2/3 for single bilayer islands, and α≃1 for three-dimensional ones. During the decomposition of three-dimensional islands, step bunching of over-layers takes place, while the islands have certain facets, like a pyramid just after the creation. At the final stages of the three-dimensional island decompositions, two-dimensional ones with 5 × 5 structure always appear. We have found that characteristic 5 × 5 islands with a long lifetime are formed during relaxation, but the 7 × 7 islands have mostlt a short lifetime. Rotation of small islands is also observed during relaxation. We discuss the results in terms of two-dimensional vapor phase processes.

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ON THE ROLE OF KINKS AND STRAIN IN HETEROEPITAXIAL GROWTH: AN STM STUDY

Surface Review and Letters ◽

10.1142/s0218625x00000750 ◽

2000 ◽

Vol 07 (05n06) ◽

pp. 673-677

Author(s):

E. LUNDGREN ◽

M. SCHMID ◽

G. LEONARDELLI ◽

A. HAMMERSCHMID ◽

B. STANKA ◽

...

Keyword(s):

Diffusion Process ◽

Scanning Tunneling Microscopy ◽

Three Dimensional ◽

Growth Mode ◽

Scanning Tunneling ◽

Two Dimensional ◽

Heteroepitaxial Growth ◽

Tunneling Microscopy ◽

Exchange Diffusion

Interlayer diffusion of Co over steps of vacancy islands on the Pt(111) surface as studied by scanning tunneling microscopy is presented. It is demonstrated that Co atoms descend Pt steps by an exchange diffusion process at the step edge with the Pt atoms. Further, the exchange diffusion process is observed to occur at the corners (kinks) of the vacancy islands. The importance of kinks concerning whether the growth mode of a heteropitaxial film is two-dimensional or three-dimensional is demonstrated for the case of thin Co films on Pt(111). We argue that the strain in the Co film is to a large extent responsible for the kink formation.

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KINETIC PATHWAY IN STRANSKI-KRASTANOV GROWTH OF Ge ON Si(001)

Modern Physics Letters B ◽

10.1142/s0217984990001732 ◽

1990 ◽

Vol 04 (22) ◽

pp. 1379-1384 ◽

Cited By ~ 2

Author(s):

Y.-W. MO ◽

M.G. LAGALLY

Keyword(s):

Scanning Tunneling Microscopy ◽

Three Dimensional ◽

Scanning Tunneling ◽

Two Dimensional ◽

Tunneling Microscopy ◽

Kinetic Processes

Scanning tunneling microscopy studies of the kinetic processes involved in the two-dimensional (2D) to three-dimensional (3D) transition in Stranski-Krastanov growth of Ge on Si(001) reveal a novel type of 3D cluster that serves as the kinetic pathway for this transition.

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Scanning Tunneling Microscopy of Amorphous Carbon Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180343 ◽

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).

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