摘要:

This paper reviews and critically assesses progress in the field of surface and near‐surface imaging microscopies based on secondary ion mass spectrometry. The ion microscope performs a variety of analytical functions, including complete mass spectra and isotope ratios from areas on the submicron scale, and lateral distribution analysis using ion imaging, with high sensitivity for all elements of the periodic table. Recent developments have improved the ion microscope’s ability to image a specimen’s elemental morphology with spatial resolutions below 100 nm. Criteria for the quantitative evaluation of ion images and the instruments that produce them are reviewed within the framework of information‐transmission theory. A complete and general description of the physical principles guiding the types of instrumentation available is thus presented, with emphasis on the accuracy and precision of an analytical measurement. Several directions for future developments are proposed.

ISSN:0034-6748    

DOI:10.1063/1.1139523

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A scanning tunneling microscope capable of operating at low temperatures,T=400 mK, and in high magnetic fields,B=8 T, is described. Accompanying electronics, under the control of an IBM PC/AT, provide routine spatially resolved spectroscopy, allowing characterization of properties such as superconducting energy gaps and local density of states on the surface. Data are presented to illustrate the usefulness of spatially resolved spectroscopy at low temperatures and in high magnetic fields.

ISSN:0034-6748    

DOI:10.1063/1.1139524

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Detailed operations of the apparatus for the stroboscopic observation of periodic phenomena at the region of line frequencies, such as the magnetic domain response, under the scanning electron microscopy are described in this paper. To achieve the stroboscopic observation at such low frequencies, a new line‐sampling technique has been introduced instead of the conventional point‐sampling method. In addition to the line‐sampling stroboscopy, a multiframe operation is also introduced to display the stroboscopic images of different phase values simultaneously. These operations are simply realized by applying the raster separation and the blanking on the display monitor scope under the multiple line‐sampling during the one‐drive period. To demonstrate the ability of this simple apparatus, some results of the stroboscopic observation of magnetic domains in an Fe–Si sample under a 60‐Hz drive field are also presented in this paper.

ISSN:0034-6748    

DOI:10.1063/1.1139662

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The positions of the lines seen in an electron channeling pattern depend on the type and orientation of the crystal producing the pattern and on the energy of the incident electron beam. It is possible to make three lines intersect at a point by altering the energy or equivalently the wavelength, &lgr;, of the incident electrons. A mathematical expression, valid for all crystal classes, is derived for this wavelength in terms of the Miller indices and plane spacings of the Bragg planes which give rise to the three lines in question. The theory has been tested by using the hexagonal layer material NbSe2. The channeling lines whose Bragg planes are (22.0), (3¯0.0), and (22¯.2¯) were found to intersect at &lgr;=0.0098 nm which leads to acspacing ofc=1.26±0.01 nm. The x‐ray value is 1.254 nm. The analysis is formulated so that it can be used on a computer without graphics facilities.

ISSN:0034-6748    

DOI:10.1063/1.1139525

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The concept of a spatial frequency‐dependent, detective quantum efficiency [=DQE( f )] is applied to the performance assessment of a prototype parallel detection system for electron energy‐loss spectrometry. The various factors which determine DQE( f ) in such a system are discussed and comparisons are made with a serial detection system. Also, the effects of the electron source energy spread on the overall spectrometer DQE( f ) are discussed. In these examples, the clear importance of including the spatial frequency dependence of DQE is demonstrated.

ISSN:0034-6748    

DOI:10.1063/1.1139526

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A deceleration system for a parallel ion beam in the energy range of 50 to 500 eV is described. The system is used for sputtering yield measurements as a function of the angle of ion incidence. Measured yield data for Cu and Au sputtered by 100‐ and 300‐eV D+ions are reported and compared to computer calculations. Experimental and calculated data show only a weak dependence on the angle of incidence. However, at glancing incidence the experimental values are larger up to a factor of 2 compared to the calculated ones. This is attributed to the surface roughness not included in the calculations.

ISSN:0034-6748    

DOI:10.1063/1.1139527

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

An instrument for photon counting measurements in a Lidar experiment is described. Single events can be stored up to rates of 25 MHz and it is capable of 4096 data acquisitions for each measurement. Time information by two successive photons is achieved with an accuracy better than 14 ns. The system is interfaced with an HP 1000F series computer. A window discriminator/shaper for formatting the photomultiplier pulses is also described.

ISSN:0034-6748    

DOI:10.1063/1.1139528

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A vidicon tube‐based optical multichannel analyzer (OMA) was interfaced to a minicomputer to facilitate the acquisition of real‐time light transmission (or fluorescence anisotropy), right‐angle scattering, and fluorescence spectra at subsecond rates. The apparatus was designed for kinetic studies of the optical responses of living cells to stimulation with physiological and other activators, and features menu‐driven interactive graphics for presentation and handling of the intensity, wavelength, and time data in two or three dimensions. Stimulus‐induced secretion of acriflavine‐loaded human blood platelet dense granule contents is shown as an example of the apparatus capabilities.

ISSN:0034-6748    

DOI:10.1063/1.1139529

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Digital optical data storage and processing are rapidly increasing in technological importance. The magneto‐optic spatial light modulator (MOSLM) is a relatively low‐cost, small pixel optical parallel input device that is capable of binary amplitude or binary phase modulation of each pixel. Thus, it is well matched to digital optical coherent storage and processing technology. However, potential problems associated with its use include: lack of a design for a general minicomputer interface, lack of interactive data‐page file generation software, lack of ability to switch single pixels in some cases, lack of remote‐from‐computer operation capability, spurious pixel switching, and catastrophic failure due to thermal effects. The hardware and software components of a versatile minicomputer interface that has been successful in overcoming all of these problems are described. This interface allows easy data entry of entire data pages or single pixels and minimizes cross talk and noise developed over long cable lengths. In tests, the designed interface has produced highly stable operating characteristics.

ISSN:0034-6748    

DOI:10.1063/1.1139530

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We have developed a low‐cost rapid‐scanning autocorrelator which enables us to monitor picosecond optical pulses up to almost 100 ps. To achieve wide‐scan range, each arm of a Michelson‐type interferometer is scanned 180° out of phase by using audio speakers, and also only one‐half of a full autocorrelation waveform of the pulses is observed. The present apparatus is usefully used to measure about 80‐ps pulses generated from a cw mode‐locked Nd:YAG laser.

ISSN:0034-6748    

DOI:10.1063/1.1139531

出版商:AIP    

年代:1987

数据来源: AIP