摘要:

We have developed anx–y–zscanning stage for mechanically scanned microscopy. The stage is constructed of ‘‘double‐S’’ mode piezoelectric bimorphs. The prototype unit has a deflection sensitivity of 0.3 &mgr;m/V and a travel in each of the three axes of ±60 &mgr;m. The lowest mechanical resonances of the stage are at 190, 220, and 360 Hz, corresponding to thex,y, andzaxes of the stage, respectively. The noise level of the stage, when mounted on an isolation table, is ∼0.1 nm. The performance of the stage can be understood in terms of a simple lumped element model which can be used to optimize such stages for particular applications.

ISSN:0034-6748    

DOI:10.1063/1.1139270

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Ellipsometry is a sensitive nondestructive optical technique which can be successfully used for determining the thickness of an optically transparent thin film deposited on a dielectric substrate. In this laboratory we have constructed a vertical null‐type ellipsometer which has been used with a homemade aluminum Teflon‐coated Langmuir trough, to study thin films at gas–water interface. Surface pressure, surface potential, and ellipsometric measurements have been performed simultaneously. Ellipsometric measurements have been done directly on the aqueous substrate contained in the trough, with and without the film, with reproducibility (±0.02°) and good signal stability (±0.1 mV) on the 10‐mV scale. The performance of the homemade instrument had been checked against the known ellipsometric properties of spread arachidic acid on acidic water solution. In this paper, details of construction and performance of the ellipsometer as well as characteristics of the trough and ellipsometric study of &bgr;‐palmitoyl‐&agr;‐oleoyl‐L‐&agr;‐phosphatidylcholine is presented. Stability of the photometric signal as a function of the structure of the film‐forming molecules is also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1139271

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We present a triple correlator for point processes in which a long batch of pulses is first recorded by direct memory access (DMA) and subsequently analyzed by a microcomputer. Provision is also made for the retrieval of the second‐order correlation function. Applications to the statistical analysis of level crossings by random noise are briefly outlined.

ISSN:0034-6748    

DOI:10.1063/1.1139219

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A spectrometer is reported here for obtaining the infrared spectrum of a single aqueous aerosol particle by a Fourier transform technique. The particle is held in an electrodynamic balance and irradiated simultaneously by the infrared output from a Michelson interferometer and the visible light from a dye laser. The size of the particle is modulated by chopping the IR beam, and the resulting visible scattered light fluctuation is detected at 90° with a photomultiplier tube. The amplitude of the scattered light fluctuation is measured with a lock‐in amplifier at each interferometer mirror position. The electronic circuitry for stepping the interferometer mirror is presented and discussed. Inverting the lock‐in signal by a discrete fast Fourier transform routine (FFT) yields the particle absorption spectrum. The resulting spectrum for an (NH4)2SO4droplet is presented.

ISSN:0034-6748    

DOI:10.1063/1.1139220

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report here on a new EXAFS laboratory facility. It features a variable Rowland radius with a source to bent crystal distance that can vary from 250 to 750 mm. It has a sample carrying table which is mechanically detached from the monochromator and can carry more than 50 lb with no effect on the monochromator. The system is completely computer controlled in such a way that the operator can control every part of the system separately as well as perform complete automatic runs. The data‐analysis programs had been divided into a general package which performs the bookkeeping of files experimental parameters and program parameters and a specific package for the analysis of the EXAFS data. The monochromator is shown to have almost theoretical resolution. We present experimental results of EXAFS on copper. The Fourier transform of these spectra agree very well with the Fourier transform of EXAFS spectra measured on a synchrotron. It is shown that the resolution of 4.5 eV of these data does not present a limitation on the quality of the data. The signal‐to‐noise ratio is, on the other hand, quite critical.

ISSN:0034-6748    

DOI:10.1063/1.1139221

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A device is described forinsitu, rotary pin‐on‐disk wear studies in a commercial scanning Auger microscope. This device is mounted on a single 8‐in. vacuum flange and can be installed in place of the normal sample mounting manipulator. The device allows simultaneous measurement of contact resistance and friction coefficient under controlled atmospheric conditions as wear progresses. The surface composition and topography of the wear track are measured without exposure of the surface to contaminating environments or removal of the pin from the wear track. Modifications made to the vacuum system to facilitate atmospheric control are also described.

ISSN:0034-6748    

DOI:10.1063/1.1139650

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A fluorescent test pattern with submicron dimensions has been produced. With this test pattern the optical characteristics of a confocal scanning laser microscope can be determined. The fabrication procedure of the test pattern and the raw data obtained in a measurement of the transfer function of the confocal scanning laser microscope are presented.

ISSN:0034-6748    

DOI:10.1063/1.1139222

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A commerical, solid‐state television camera has been used to record images of soft x radiation (0.8–12 keV). The performance of the camera is theoretically analyzed and experimentally evaluated compared with an x‐ray photographic film (Kodak direct exposure film). In the application, the camera has been used to provide image patterns of x rays from laser‐produced plasmas. It is demonstrated that the camera has several advantages over x‐ray photographic film.

ISSN:0034-6748    

DOI:10.1063/1.1139223

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A steady concentration gradient is maintained in a narrow vertical diffusion channel making it possible to determine the concentration dependence of the diffusion coefficient in one single experiment. The gradient is sustained by a simple transport system and is observed interferometrically. The apparatus is tested using calcium chloride and sugar. The method is rapid and the results agree fairly well with those reported in the literature. Analyses of the flow velocity and the time to reach the steady state are given.

ISSN:0034-6748    

DOI:10.1063/1.1139224

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A description is given of the prototype polarized neutron reflectometer installed at the intense pulsed neutron source. This instrument is designed for determining the magnetic depth profiles near the surfaces of ferromagnets and superconductors, by measuring the spin‐dependent reflectivities of a well‐collimated (0.01°) beam of cold neutrons from surfaces of a few cm2. Magnetic profiles can be determined with the spatial resolution of 40 A˚, over thicknesses up to 5000 A˚. Variations of the magnetic flux of the order of 10−5G cm2can be detected.

ISSN:0034-6748    

DOI:10.1063/1.1139225

出版商:AIP    

年代:1987

数据来源: AIP