摘要:

AbstractNanofabrication on silicon surfaces has been achieved in a manner similar to e‐beam/resist technology, in which hydrogen serves as a monolayer resist for exposure by the electron beam from an ultrahigh vacuum (UHV) scanning tunneling microscope (STM). In this scheme, hydrogen is selectively desorbed from Si(100)2×1:H surfaces that have been prepared by atomic hydrogen dosing under UHV background conditions. To remove hydrogen, the tip bias is raised, under feedback control, and then the desired pattern is drawn. Two regimes of hydrogen desorption are observed: at higher energies, above ∼6.0 V, direct electron‐stimulated desorption occurs, whereas at lower biases, desorption occurs via a multiple excitation vibrational heating mechanism and exhibits a strong current dependence. Patterning linewidth down to a single dimer row has been achieved in the vibrational heating regime. The selective removal of hydrogen suggests many possibilities for subsequent chemical treatments in which the hydrogen‐terminated silicon remains inert. We have performed experiments which demonstrate selective oxidation of, and nitrogen incorporation into, the STM‐pattern

ISSN:0021-2148    

DOI:10.1002/ijch.199600003

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractResearch by our group aimed at studying the chemistry of surfaces with atomic‐resolution scanning tunneling microscopy is reviewed. Three areas of application are discussed: semiconductor surface chemistry, adsorption processes at metals, and in situ studies of dissolution and oxidation‐reduction chemistry of miner

ISSN:0021-2148    

DOI:10.1002/ijch.199600004

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA review is given of scanning tunneling microscopy (STM) studies of reactions between different chemical species on metal surfaces. Results presented for a variety of systems show that STM can give unique insight at the atomic level into the mechanistic details of surface reactions and decomposition of molecules. This is illustated with a number of examples of reactions occuring on single‐crystal metal surfaces, such as Ni(110), Cu(110), Ag (110), Rh (110), and Pt(111). The ability of the local STM probe to study the influence of defect sites on reactivity is highlighted, and similarities and differences in reactivity of different systems are discussed. Finally, the application of STM to enhance reactivity via tip interactions is addresse

ISSN:0021-2148    

DOI:10.1002/ijch.199600005

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractSolid‐phase epitaxy (SPE) of thin silicon film with a thickness of 0.2–2 bilayers (BL) on Si(111)‐(7 × 7) surface was studied by scanning tunneling microscopy. At small coverage, the SPE growth proceeds via coarsening of islands. As the coverage exceeds the percolation threshold, a ‘mirror’ process consisting of coarsening of voids in the continuous layer takes place. The SPE growth of a thicker continuous layer results in a partly disordered flat surface, displaying a mixture of different reconstructions. Quantitative characterization of this surface by the formalism of pair distribution functions reveals an anisotropy in the orientational order that may indicate that SPE occurs preferably in the step direction. A possibility to use an SPE‐grown layer as a two‐dimensional model for bulk processes in solid

ISSN:0021-2148    

DOI:10.1002/ijch.199600006

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe co‐adsorption of pre‐ and post‐annealed C60molecules on Si(100)‐2×1 surfaces has been investigated using scanning tunneling microscopy in ultrahigh vacuum. The images reveal that the adsorption characteristics of the post‐annealed adsorbates are different from their pre‐annealed counterparts. The post‐annealed C60molecules bond either to the top of the dimer rows or to the missing dimer defects, while the pre‐annealed molecules predominantly occupy the four‐dimer sites in the troughs. The apparent size and height of post‐annealed C60molecules are smaller than those of the pre‐annealed ones. Our observations suggest that the post‐annealed C60molecules are chemisorbed on the surface, because the molecules covalently bond to Si atoms during the sample annealing. In contrast, the adsorption of the pre‐annealed C60molecules can be explained by a dipole‐induced‐dipole interaction between the molecules and the Si(100

ISSN:0021-2148    

DOI:10.1002/ijch.199600007

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractSurface features and adsorbates perturb the electronic properties of the surrounding substrate surface. This modifies the adsorption, dynamics, and chemistry of nearby atoms and molecules. Using scanning tunneling microscopy, we have imaged these perturbations and the resulting ordering and dynamics for benzene on Cu{111} at low temperature and dilute coverage. We discuss the important implications that substrate‐mediated interactions can have on the atomic‐scale mechanisms and control of film growth and heterogeneous selective cataly

ISSN:0021-2148    

DOI:10.1002/ijch.199600008

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe images of benzene on Pt(111), as obtained by the scanning tunneling microscope, have been calculated theoretically. The simulations show that the shape of the molecule pattern in the image is strongly dependent on the chemisorption site on the surface, in agreement with the experimental data. For a given site, the variations of the images with the geometric parameters of the adsorption are discussed. The internal structure of the pattern is enhanced when the molecule is more distorted or adsorbed closer to the surface. By a decomposition of the calculated image on different subsets of molecular orbitals, the shape of the hollow site image is analyzed in detail. It is shown that is is not possible to restrict the calculation to the π orbitals of benzene and that the s orbitals built from the 2s atomic orbitals of carbon play an important role

ISSN:0021-2148    

DOI:10.1002/ijch.199600009

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe scanning electrochemical microscope (SECM) is one of the scanning probe techniques that have been developed following the introduction of the scanning tunneling microscope. The approaches that have been used to modify surfaces with lateral resolution using the SECM are presented and discussed. These approaches made it possible to drive a variety of microelectrochemical reactions on surfaces, as well as to study the mechanism of these processes due to the unique advantages that the SECM offers.

ISSN:0021-2148    

DOI:10.1002/ijch.199600010

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe atomic force microscope (AFM) measures force and displacement with high sensitivity and submillisecond temporal resolution. By functionalizing the AFM probe with specific chemical groups or macromolecules it is possible to characterize the chemical and physical properties of single molecules on the nanometer scale. In this paper we discuss the key issues that must be addressed when designing and characterizing a successful immobilization chemistry, and describe the chemistry we developed to covalently immobilize oligonucleotides in a specific orientation.

ISSN:0021-2148    

DOI:10.1002/ijch.199600011

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractDuring the past decade the area of near‐field optics has seen an exponential growth. This is a result of the resolution of the technical problems that had prevented the potential of this powerful optical methodology from being generally applied. As a result of committed and steady progress in resolving these technical problems the fundamental principles of near‐field optics are now generally accepted and the technology is widely used. The potential of these advances has important implications in a variety of areas, from chemistry to information storage to the characterization of structures with potential in fundamental mesoscopic physics, and in the characterization of practical devices in electronics and photonics which are rapidly reaching nanometer dimensionalities. In this paper, the progress that has been made in Jerusalem in developing a near‐field microscope fully integrated with conventional far‐field, confocal far‐field, and all forms of force and other scanned probe microscopies will be described. The potential of this unique imaging system in chemical applications is also

ISSN:0021-2148    

DOI:10.1002/ijch.199600012

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY