摘要:

The x‐ray response of an 800×800 Texas Instruments virtual phase charge‐coupled device (CCD) has been measured in the range 1–8 keV. In the single‐photon counting mode, we find excellent energy resolution (∼250 eV FWHM) for single‐pixel Fe55x‐ray events at a spatial resolution of 15 &mgr;m. The detector quantum efficiency for all events is 65% at 2.3 keV (SKline) and ∼34% at 5.9 keV (MnKline from Fe55). The CCD response is linear in energy to a few percent over the 1–8 keV energy range. These results demonstrate that virtual phase CCDs are superior imaging x‐ray spectrometers with applications for x‐ray astronomy and laboratory plasma research.

ISSN:0034-6748    

DOI:10.1063/1.1137345

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Double‐axis x‐ray spectrometer measurements at flat, low‐absorbing mosaic crystals produce broad and asymmetric Bragg‐reflection profiles. If the absorption coefficient changes during the sample preparation process, as in the case of graphite and graphite intercalation compounds, a determination of the instrumental profile is almost impossible. Using triple‐axis spectrometers, the Bragg‐reflection profiles are independent of the sample transparency, and peak profiles can be determined with high resolution and minor corrections.

ISSN:0034-6748    

DOI:10.1063/1.1137346

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

An instrument measuring the temperature dependence of minority‐carrier lifetimes without contacts is described. The temperature range is 100 to 420 K, and the shortest decay time observed is about 2 &mgr;s. The instrument utilizes the photo decay of microwave power reflected from the sample, therefore, it is a contactless method. As an example, the instrument was applied to high‐quality silicon crystals used in very large scale integrated circuit fabrication. The measured temperature dependence could be explained by the Shockley–Read–Hall theory by assuming a level for the recombination centers at 0.18 eV from the valence band.

ISSN:0034-6748    

DOI:10.1063/1.1137347

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We have constructed an apparatus which enables one to measure, simultaneously, the shear modulus, the viscosity, and the surface pressure of a monomolecular film on water under a hydrostatic compression. It is particularly suitable for measurements of the static shear modulus of insoluble monolayers. A capillary wave generator/detector system was also incorporated to determine the surface pressure. The trough is a Teflon cup 12.7 cm (5.4 in.) in inner diameter with sloping interior sides. As the cup is raised, while maintaining the water elevation fixed, the film is uniformly compressed. A rotor suspended at the center from a fine torsion fiber is used to measure the mechanical properties (surface viscosity and/or surface shear modulus). To measure the quasistatic shear properties, the cup is rotated through a small angle and the residual deflection of the rotor determined. Dynamic shear response is probed by studying transient torsional oscillations following a sudden angular displacement of the torsion fiber. There are no barrier seals and circular symmetry is maintained at all times. The apparatus has a resolution of 5×10−4surface poise of shear viscosity and 1×10−4dyn/cm of static shear modulus.

ISSN:0034-6748    

DOI:10.1063/1.1137348

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A practical means has been established for starting a discharge between refractory metal electrodes in ultrahigh vacuum and to sustain it stably for a long time. Thin single‐crystal films were thus obtained. Unlike what is done in the sputtering method, no inert gas is used here. The emission of gaseous particles in the present method occurs due to plasma power, the particles having, therefore, an appreciable amount of kinetic energy. This fact distinguishes it from the E‐gun method, in which evaporated particles are not energized. We present, as an example, the results obtained when applying the method to tungsten. The gas supply that sustains the plasma state comes from the melting surface of two rod‐shaped electrodes surrounded by a helical filament. The arc‐type discharge, easily starts by applying an input voltage of only about 1.5–2.5 kV between the electrodes while simultaneously bombarding them with electrons emitted from the filament, and is electrically controlled by a load resistance and a servo mechanism continuously adjusting the gap between the consuming electrodes. A stationary discharge is, therefore, attained. Starting voltages are quite reproducible and depend little on the gap length, provided that this last parameter is less than about 2 mm. The discharge, closely related to both discharge power and gap length, is of practical use only within a stable region. Excessive power supply produces splashing of the electrodes, while insufficient power results in the disappearance of the discharge. The evaporation rate depends on the power of the plasma column. Effects due to partial pressure of materials other than that of rods are sufficiently eliminated by the ultrahigh vacuum system.

ISSN:0034-6748    

DOI:10.1063/1.1137349

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

An extensometer extender has been constructed which allows the use of room‐temperature extensometry for measurement of axial strain at high temperatures. The device can accept most commercial extensometers, is inexpensive to build, and easy to use. No modification of extensometer electronics are required. This paper describes the design requirements for high‐temperature extensometry and shows how the present design meets these criteria. Drawings and rationale for construction are given so that the device may be easily modified for specific applications. Use of the device for strain controlled low‐cycle fatigue of soft specimens at elevated temperatures demonstrates the success of this design.

ISSN:0034-6748    

DOI:10.1063/1.1137350

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A new electrochemical instrument is described that permits the rapid and precise measurement of electrode parameters of reaction. The described techniques, previously called electrochemical potential spectroscopy, are particularly valuable in studying solid‐state reactions and phase transitions and are generally useful whenever approximations to equilibrium data are required on slow processes. The instrument may also be viewed as a general purpose instrument for measurement of electrical capacitance. It automatically measures the voltage–composition– current–time relations on an electrochemical cell by systematically stepping the voltage through a series of programmed constant voltage steps. The instrument is designed for three‐electrode measurements and has been fully developed and tested on a large number of electrochemical systems. Three commercial lithium cells are measured to illustrate the method, its time saving advantages, and its weaknesses. Comparison is also made to open circuit data collected on Li–V2O5. Three electrode measurements are reported elsewhere.

ISSN:0034-6748    

DOI:10.1063/1.1137351

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A new thermal conductivity cell is described which can be used to measure the bulk thermal conductivity and the thermal contact resistance of paper and other thin‐film materials. The cell incorporates a hydraulic piston which can apply pressures up to 1700 psi to the sample which is situated between the optically flat end faces of two brass columns. By measuring the thermal resistance of paper samples of various thicknesses, it is demonstrated that a pressure of 1700 psi effectively eliminates the thermal contact resistance. By comparing measurements at zero and maximum applied pressure, both the bulk conductivity and the contact resistance can be calculated. This is illustrated with several types of paper. In all cases, there is a qualitative correlation between the measured contact resistance and the surface roughness of the sheet. The technique can also be used for thin polymer films, and for layered structures such as the ink donor films used in thermal transfer printing.

ISSN:0034-6748    

DOI:10.1063/1.1137352

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A computer interface for a PARC model 1205A Optical Multichannel Analyzer (OMA) is described. This interface uses the output from the OMA’s internal analog‐to‐digital converter rather than the usual parallel I/O facility. The ADC output is transmitted from the OMA to the computer over a single 75‐&OHgr; coax cable. Since the data obtained from each OMA scan may be stored in the computer memory, extremely versatile processing algorithms may be used, and normal OMA operation is not affected. The software used is also described.

ISSN:0034-6748    

DOI:10.1063/1.1137353

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The lower section of the sample drive rod and sample holder of a P.A.R. Model 155 vibrating sample magnetometer has been modified in order to allow measurements to be made on both powder and variously shaped and sometimes large single‐crystal samples, and to allow a carbon‐glass thermometer to be mounted very near the sample.

ISSN:0034-6748    

DOI:10.1063/1.1137354

出版商:AIP    

年代:1983

数据来源: AIP