摘要:

A cylindrical energy analyzer with drift spaces is shown to have a second‐order focusing for beam incident angle when the deflection angle is properly chosen. The analyzer has a possibility to be applied to MeV range heavy‐ion beam probes, and will also be available for accurate particle energy measurements in many other fields.

ISSN:0034-6748    

DOI:10.1063/1.1144275

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

The mechanical properties of very small volumes of material can vary greatly from bulk properties. These modified properties are of interest in many areas including the operation of atomic force microscopy (AFM), the study of adhesion and fracture, and the evaluation of electrical contact response. Despite the importance of these properties, AFM has not yet been successfully utilized for their investigation. Most existing AFMs still rely on the control and monitoring of displacements, with forces being inferred from spring constants. This would be fine if other interactions, such as those between the tip and the surface, were minor perturbations. However, this is frequently not the case, particularly for contact mode AFM. Hence very little is known about the forces applied in the contact and their affect on both the tip and the sample. In this article we describe an AFM probe where forces rather than displacements are applied to the tip. This allows absolute determination of contact compliance and hence provides a measure of the tip–surface interaction. As an example of its use we show quantitatively the effect of the adsorbed water and meniscus forces present in ambient probe microscopy.

ISSN:0034-6748    

DOI:10.1063/1.1144276

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A bipolar amplifier, optimized to control a piezo translator of a scanning tunneling microscope, is described. The apparatus is completely designed using discrete components and it offers a very simple solution to controlling movement of any piezo translator.

ISSN:0034-6748    

DOI:10.1063/1.1144472

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

An ultrahigh vacuum atomic force microscope (UHV–AFM) with tunneling current detection has been developed. This microscope uses a new type of pantograph inchworm system. The features of the inchworm system are (i) operation of the clamp in normal clamping mode, (ii) an enlargement of the piezo device stroke for clamper stroke, and (iii) compact system for easy use. Our UHV–AFM has (i) six inchworm movements based on the new mechanism, and (ii) a sharp AFM probe whose tip is machined by a focused ion beam fabrication technique. UHV pressure experiments demonstrate that this system provides a contamination‐free surface and can observe atomic resolution AFM images of MoS2and silicon carbide.

ISSN:0034-6748    

DOI:10.1063/1.1144277

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A general purpose data acquisition and control system for scanning tunneling microscopy (STM) using Visual Basic is presented. This Windows hosted Visual Basic environment is highly desirable for use in STM image manipulation, storage, and printing, but in its standard form is not suitable for most data acquisition and display applications. Many of the inherent limitations in the Visual Basic language have been overcome by the use of direct calls to the Windows Application Program Interface. In this paper, we describe a general Visual Basic STM user interface and control system, and the extensions to the language using the Windows API needed to implement this system.  

ISSN:0034-6748    

DOI:10.1063/1.1144278

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

We developed a piezoelectric scanner for probe microscopes that uses only single‐domain LiNbO3crystals as a piezoelectric transducer material in order to avoid nonlinearity, hysteresis, and creep that is always present in piezoelectric ceramics. A raster area of about 50×50 nm2is within reach of a scanner that uses three double‐plate translators and a scanning voltage of 300 V peak to peak. The performance of monocrystal scanners for investigations in the range of atomic resolution is demonstrated by imaging the well‐known surface of highly oriented pyrolytic graphite.

ISSN:0034-6748    

DOI:10.1063/1.1144279

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

We present a simple and general purpose implementation for monitoring the lateral forces between a near‐field optical probe and a surface. A feedback system based on this technique has been incorporated into a near‐field optical fabrication system based on heatless material removal with an argon fluoride excimer laser. This has allowed the construction of an instrument that is capable of directly patterning a wide variety of materials with a resolution of less than 50 nm.

ISSN:0034-6748    

DOI:10.1063/1.1144280

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A new high‐speed digital framing camera is described. The design is built around a rotating polygon mirror that provides a framing rate of 24 000 frames/s. The camera electronics digitizes an image into a 32×104 grid of pixels, where the second dimension of the grid can be varied and is determined by the 8 bit computer‐aided measurement and control digitizer sampling rate. Available digitizer memory provides for 314 frames at this horizontal resolution. The advantages over other available high‐speed framing cameras are (1) low cost of the system provided the digitizers are available, (2) rapid retrieval of a recorded event, and (3) the ease with which the system can be used. Sample results from an application in high‐power arc photography are given to illustrate the system’s spatial and temporal resolution.

ISSN:0034-6748    

DOI:10.1063/1.1144281

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

Computational aspects of a new matrix equation‐based thermal‐wave subsurface diffraction tomographic method for object field reconstructions of transverse slices (planes) perpendicular to a material surface are presented. The method can be implemented on conventional workstations and mainframe computers. It uses the photothermally measured backpropagation (front detection) or transmission (back‐surface detection) scanned thermal‐wave field data in the solution of the Helmholtz thermal pseudowave equation, by solving the equivalent integral equation. The numerical computations of the inverse problem used in the slice image reconstruction were satisfactorily carried out via the Born approximation. Simulated thermal‐wave tomographic data/case studies were used to evaluate the imaging characteristics of large‐scale computational thermal‐wave diffraction tomography as a quantitative measurement and nondestructive evaluation imaging discipline.  

ISSN:0034-6748    

DOI:10.1063/1.1144282

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

It has been found that the photopyroelectric (PPE) sensor made of thin‐film polyvinylidene fluoride, sputter coated with palladium, can detect trace hydrogen gas in the presence of pure oxygen without significant drift and stabilization problems. Presently, hydrogen concentration as low as 0.1% in flowing 99.9% oxygen has been detected under standard temperature and pressure conditions. The detector has been used without a reference sensor (single mode) which simplifies the sensor system compared to previous work, at the expense of sensitivity limits. This paper describes the detection of hydrogen gas in hydrogen/oxygen mixtures, and deals with some instrumental aspects of the PPE sensor device such as background noise and signal drift. Some techniques for stabilization are also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1144283

出版商:AIP    

年代:1993

数据来源: AIP