摘要:

From a linear motion equation, the precise linear internal friction expression for the free decay method has been deduced for the first time. A detailed comparison between the newly deduced expression and the currently used approximation has also been addressed.©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148253

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on a compact loading cell for the continuous variation of uniaxial forces up to a few tons in low temperature investigations. The cell is based on a He activated bellow and a mechanical force amplification system. Due to its modular design, it may be used in studies of the effect of uniaxial pressure on solids or thein situvariation of hydrostatic pressure in an anvil cell. High pressure He is supplied by a fine capillary, so that bellow, force amplifier, and experiment may be cooled uniformly to mK temperatures even at high magnetic fields. The pressure in the bellow is controlled by a simple proportional-integral regulator at room temperature. Characteristic features of a piezoelectric sensor, used to measure the load at low temperature, are presented in detail. With the method described here, we observe long-term stability to better than ±0.2 N in sweeps over a wide range of temperatures and fields. The performance of the loading device is illustrated by means of measurements into the superconducting state ofURu2Si2. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148254

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Oblique illumination has superseded the use of lenses in the optical reconstruction of shearograms. Nevertheless, the mechanism behind this operation has, hitherto, not been clearly elucidated. In this article, we describe this mechanism via the use of ray and wave optics principles. A comparative analysis of the performances using white-light and monochromatic illumination is also furnished. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148255

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A versatile modular setup is described which incorporates ellipsometry, surface plasmon spectroscopy, waveguide modes, their corresponding imaging techniques and Brewster angle microscopy in a single instrument. The important design criteria are discussed with special emphasis given to the requirements imposed by imaging under an oblique angle of incidence. Several experimental examples demonstrate the power of the instrument. Imaging nullellipsometry of a patterned monolayer on a highly reflecting support demonstrates a lateral resolution of approximately 1 &mgr;m and an accuracy in the thickness determination in the sub-nm region. The localization of the evanescent field of a surface plasmon was exploited to characterize adsorption layers in turbid and thus highly scattering solutions. An example of how an anisotropic sample can be characterized with the aid of waveguide modes is provided. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148256

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present an ellipsometric technique and ellipsometric analysis of repetitive phenomena, based on the experimental arrangement of conventional phase modulated ellipsometers (PME) conceived to study fast surface phenomena in repetitive processes such as periodic and triggered experiments. Phase modulated ellipsometry is a highly sensitive surface characterization technique that is widely used in the real-time study of several processes such as thin film deposition and etching. However, fast transient phenomena cannot be analyzed with this technique because precision requirements limit the data acquisition rate to about 25 Hz. The presented new ellipsometric method allows the study of fast transient phenomena in repetitive processes with a time resolution that is mainly limited by the data acquisition system. As an example, we apply this new method to the study of surface changes during plasma enhanced chemical vapor deposition of amorphous silicon in a modulated radio frequency discharge ofSiH4.This study has revealed the evolution of the optical parameters of the film on the millisecond scale during the plasma on and off periods. The presented ellipsometric method extends the capabilities of PME arrangements and permits the analysis of fast surface phenomena that conventional PME cannot achieve. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148257

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A versatile and very low-cost programmable pulse generator for nuclear magnetic resonance is reported. The apparatus consists of basic transistor–transistor logic devices, and is equipped with independent 16 channel outputs. Each of the pulse widths and intervals are adjustable in 0.1 &mgr;s resolution. The pulse sequence is made on a 32 bit personal computer, and transferred to the pulse generator hardware through the Centronics printer interface. No additional interface is necessary for a standard personal computer. The pulse data are initially stored in static random access memories, and then read out to construct 16 channel pulse arrays. The apparatus was used for pulsed field gradient spin-echo nuclear magnetic resonance experiments combined with rotation of a quadrupole coil. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148258

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A method for measuring the nonlinear coefficients of piezoceramic resonators with low signal excitation is presented. It consists of the intermodulation produced by two signals with variable amplitude and closely spaced in frequency at the neighborhood of the resonance, performing the measurement of the intermodulation distortion signals at frequencies near excitation. This method is highly sensitive and allows nonlinear measurements to be taken at relatively low levels, avoiding thermal effects. The module and argument of the nonlinear increase in the impedance can be determined by the analysis of these measurements. This method is compared with other previously used methods, and the advantages of the proposed method are analyzed. The described nonlinear coefficient allows us to understand and foresee the nonlinear behavior near the resonance: amplitude-frequency shift effect, decrease of mechanical quality factorQ,and the jump phenomenon observed in frequency sweeps. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148259

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A high pressure, optical system is presented for measuring the refractive index of a supercritical fluid solvent to within±3×10−3at pressures as high as 2500 bar and temperatures of 200 °C. The experimental technique used here is an adaptation of the laser beam displacement method for measuring the refractive index of liquids at ambient pressure. This optical system is used to measure the refractive index of supercritical ethane to pressures of 2000 bar and temperatures of 200 °C. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148260

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

An experimental setup for Fourier transform infrared (FTIR) studies in condensed matter at high pressure and low temperatures is described. We have adapted a close-cycle cryostat(T=20–300K) to the sample compartment, which is used as a cryo chamber, of a FTIR spectrometer (frequency range 10–15 000cm−1).A Cassegrain-type beam condenser is assembled to measure infrared absorptions of samples contained in a membrane diamond anvil cell(Pup to 100 GPa). The tuning of the pressure and the cell alignment is performed from outside the evacuated instrument. An additional light path allows visual observation andin situpressure calibration. The advantages of this system, demonstrated by its application toCH4andAr–(H2)2crystals, are high radiation throughput, long time stability, visual observation of the sample, remote measurement and variation of the local pressure, and remote alignment of the cell with the IR beam. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148261

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Contaminant particles peculiar to a type of equipment emanate inside and around a semiconductor, or thin-film-transistor–liquid-crystal-display device fabrication front-end equipment. To analyze such deposition phenomena and implement contamination control measures, it is necessary to observein situdeposition behavior over a long period. This article describes a measuring instrument for this purpose. Deposition and tearing off of particles or mist take place on the surface of a transparent plate (of glass or quartz) and Mie scattering occurs when a laser beam is irradiated onto the particles or mist from below. The scattered light is detectedin situwhile the detection signals are accumulated and kept track of. In this instrument, a semiconductor laser with beam focusing optics and an ellipsoidal mirror are integrated into a small, portable unit. The laser beam is scanned onto the glass surface over a maximum area of 250 by 250 mm in one or two dimensions. It is possible to adjust the scanned area, scanning speed, and laser beam diameter. One-spot, fixed irradiation is also possible for detection of particle flow or tearing on the surface. The minimum detectable particle size was about 0.3–0.4 &mgr;m for polystyrene latex sphere (PSL) particles deposited on the glass surface with a beam diameter of 35 &mgr;m and a scanning speed of 0.3 m/s (0.14 &mgr;m for a silicon wafer surface). Two kinds of experiments were carried out by the use of one glass with PSL particles deposited on the surface and another glass on whose surface PSL particles were spouted so they would roll without deposition. By using this instrument, it became clear that the response curve for the rolling of the particles agreed well with the Mie equation, whereas the curve for the deposited particles deviated from the equation, but only in the range of minute particle sizes. Another phenomenon clarified throughin situmeasurement was that once deposited, real-world particles were subjected to the influence of the down flow of clean air (0.3 m/s), and some were torn off in a time period on the order of hours. A comparison of the real-world particle deposition rate was made between the grounded and ungrounded states using a glass plate with a transparent conductive thin film. An increase in the deposition rate was observed for the ungrounded state, while a remarkable tearing-off rate was seen for the grounded state. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148285

出版商:AIP    

年代:1997

数据来源: AIP