摘要:

The keynote sets the stage for all that is to come. In the next five days we will learn where we are now and where we are going. The scanning probes provide us with data that is quite new and informative. Of course, we must still rely on all of the tools from other disciplines for a complete investigation of a given problem, but nonetheless, there is an established regime where the probes are supreme. The 7×7 reconstruction of the silicon (111) surface is a primary example where the tunneling current provides new information that is not obtainable with other means.1Our knowledge of this surface has reached the point where we can make detailed measurements of the electronic structure2and chemical reactivity3of each atomic site on this reconstructed surface. The theorists have been challenged by the data and they are stretching their calculations to new limits. The study of steps on this surface serves as an example where the new methodology is useful over a larger scale. It is hard to imagine how the structure of multiple steps,4or the details of the distribution of steps,5could be obtained with other technologies. Throughout this conference the topics, selected from various fields and multiple disciplines, will demonstrate the unique character of the scanning probes. Our progress has been chronicled by the editors who are responsible for the covers of technical and scientific magazines. We list the covers that they have chosen in Table I. In Table II we list book covers. The images started to appear in 1986. The year 1987 was a poor year; we did not find a single entry. But the interest picked up in 1988, in 1989, and again in 1990. We are confident that the trend will continue well beyond 1991.

ISSN:0094-243X    

DOI:10.1063/1.41412

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The Scanning Tunneling Microscope (STM) has stimulated a range of new microscopies which essentially use the same scanning and feedback principles to obtain nanometer resolution images. In this contribution, we review the history of scanned probe techniques and discuss some of the new directions that have evolved with particular reference to work done in our own group.

ISSN:0094-243X    

DOI:10.1063/1.41408

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Super resolution optical microscopy in the near field will be discussed. A brief survey of the principles of the method of near field scanning optical microscopy will be presented along with selected results and demonstrations that resolutions an order of magnitude smaller than the wavelength can be achieved.

ISSN:0094-243X    

DOI:10.1063/1.41417

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A type of scanned probe optical microscopy using evanescent fields generated by the total internal reflection of light is described. The fundamental principles of this form of microscopy, called photon scanning tunneling microscopy (PSTM), are discussed. Data is presented to illustrate the behavior of the evanescent field used by the PSTM. Demonstrations of PSTM imaging and spectroscopy are presented, and future applications are suggested.

ISSN:0094-243X    

DOI:10.1063/1.41386

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

New modes of operation of a scanning tunneling microscope (STM) with infrared laser radiation coupled into the tip of the tunneling junction are demonstrated. Difference frequency generation of two laser beams is observed to be caused by the nonlinearity in the current‐voltage characteristic of the junction. The dc current produced by laser‐light rectification and the difference frequency signal are used to obtain atomic resolution surface images of graphite, as well as to control the tip‐sample distance. Such a laser‐driven STM can generate surface images without external bias voltage, and‐when the difference frequency signal is used for the distance control‐even without any dc current between tip and sample. This mode of operation may also allow to study surfaces of insulators.

ISSN:0094-243X    

DOI:10.1063/1.41397

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have demonstrated a new type of near‐field microscope based on the principles of the liquid immersion real‐time confocal scanning optical microscope, with the liquid replaced by a solid material of high refractive index. By using this microscope as a real‐time near field imaging system, a factor of two improvement in the edge response over a confocal microscope has been obtained. The system should also have the advantage that it can image inside a material of high refractive index with a better definition than in air.

ISSN:0094-243X    

DOI:10.1063/1.41404

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

By exploring the surface of an illuminated object at a very short distance by means of a subwavelength detector, it is possible to reconstruct images whose resolution is beyond the diffraction limit. This opportunity due to near field properties can be explained in terms of non radiative field detection that is of optical tunneling effect. We present some recent results obtained by using two different illumination‐detection configurations. The first one using internal reflection allows to analyze the surface of transparent objects whereas the second one using the same tip as subwavelength emittor and detector is suitable for reflecting objects.

ISSN:0094-243X    

DOI:10.1063/1.41405

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An Evanescent Field Optical Microscope (EFOM) is presented, which employs frustrated total internal reflection on a highly localized scale by means of a sharp dielectric tip. The coupling of the evanescent field to the sub‐micrometer probe as a function of probe‐sample distance, angle of incidence and polarization has been characterized quantitatively both experimentally and theoretically. The coupling efficiency of light into the tip agrees with a description based on complex Fresnel coefficients. By scanning the tip images have been obtained of non‐conducting dielectric samples, periodic gratings and non periodic structures, containing both topographic and dielectric information which clearly demonstrate the capacity of the evanescent field optical microscope for nanometer scale optical imaging. The effect of field gradient, tip‐sample distance, polarization direction and tip artifacts on the images has been investigated. Recent results are presented.

ISSN:0094-243X    

DOI:10.1063/1.41406

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The low temperature scanning tunneling microscope, STM, is capable of measuring the local density of states across a surface of a superconductor. This allows vortices and the flux lattice to be imaged by measuring the spatial variations in the local tunneling spectra. Different vortex energy eigenstates can be imaged depending on the tip sample bias. The evolution of the conductance spectrum as the tip passes over the vortex core reveals several subgap peaks. The energy position of these peaks vary with radius and may provide a measure of the coherence length. Angle dependent anisotropies may reflect further complications from the details of the Fermi surface.

ISSN:0094-243X    

DOI:10.1063/1.41407

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

In small capacitance tunnel junctions charging effects can play a significant role or even dominate the tunneling behavior. For a complete description the electrodynamics of the environment have to be taken into account in a proper quantum‐mechanical way. For planar junctions this is now well understood. For STM‐type junctions the situation is less clear. Several experiments will be described which shed some light upon this problem, and the consequences for normal STM operation will be discussed.

ISSN:0094-243X    

DOI:10.1063/1.41428

出版商:AIP    

年代:1991

数据来源: AIP