摘要:

In this article, a contamination-irradiation facility designed to measure contamination effects on far-ultraviolet optical surfaces is described. An innovative feature of the facility is the capability of depositing a contaminant, photopolymerizing the contaminant with far-ultraviolet light, and measuring the reflectance of the contaminated sample, allin situ. In addition to describing the facility, we present far-ultraviolet reflectance measurements for a contaminated mirror. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149152

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A novel four nuclear magnetic resonance (NMR)-tube holder is described for quantitative Raman and resonance Raman spectroscopy. This cell has advantages over other divided cell designs in producing high precision quantitation and eliminating off-axis errors. Raman spectra were obtained for both absorbing and nonabsorbing solutions, and the results compared to those obtained using a single tube holder. The relative Raman intensities in a 1:1 mixture of benzene and chloroform taken in the single holder were within 6&percent; of those of the pure solvents taken with the four NMR tube holder. The resonance Raman scattering cross section of chromate was determined to be within 6&percent; of the value obtained from a single-tube holder. All of these errors in accuracy and precision are within the errors normally associated with the quantitative measurement of Raman cross sections. These results show that the four-tube holder can be used for precise and accurate measurement of both Raman and resonance Raman scattering. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149153

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Conventional dispersive Fourier transform spectrometry (DFTS) is a powerful tool for determining optical constants of materials. However, the refined and intrinsically high-cost mechanically scanned interferometers that are necessary are not well suited to use in hostile environments or for time-resolved operation. We describe here a novel approach to DFTS that employs a combination of a Wollaston prism and a linear detector array. It is ideally suited to the precision characterization of thin films with physical thicknesses of up to about 1000 wavelengths or typically about 1 mm. The simplicity and optical efficiency of conventional DFTS are combined with the inherent robustness, superior time resolution, and high repeatability of spatial interferometry. The technique offers an optical throughput that is an order of magnitude higher than spectrophotometry or spectral ellipsometry while accuracies of 1 part in104and repeatability of 1 part in105are possible for the measurements of the real part of the refractive index. The imaginary component of the refractive index of thick transparent samples has been measured with an absolute error of less than2×10−4.The technique may be readily applied from the vacuum ultraviolet to the mid infrared. We present proof-of-principle measurements of optical constants at wave numbers between 9000 and 25 000 cm−1for a self-supporting film of Melinex and for a thin film of ZnSe grown by molecular beam epitaxy onto a glass substrate. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149154

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Doping techniques are of great importance in developing new materials and devices. We present here a novel approach for doping impurity in thin film by using dual-beam pulsed-laser deposition technique that allowsin situcontrolling doping under a wide range of conditions. We demonstrated doping Agin situinYBa2Cu3O7−&dgr;thin films and for the first time observed long bar-like Ag structures with a length up to 150 &mgr;m in the as-deposited films, which may have important application in the fabrication of superconductor-normal metal-superconductor Josephson junctions. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149168

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Dedicated to the investigation of the temperature dependence of mechanical stress in thin films (up to700 °Cin vacuum), a sensitive apparatus has been built up to measure the substrate curvature of a beam-shaped sample by deflection of a splitted laser beam from both ends. The measuring sensivity is about 0.1 MPa for a typical film thickness of 1000 nm. The long-term value over 24 h is about±0.5 MPadue to ambient-temperature drifts. The determination of absolute stress magnitudes is possible by comparative measurements between the measuring bending beam and a reference one before and after film deposition or film removal. Investigations on sputteredCu0.57Ni0.42Mn0.01films have shown that (1) the stress relaxes above300 °Cand remains nearly constant between 430 and550 °Cduring the first heating, (2) a hysteresis behavior occurs during the repeated cycles, and (3) the stress at room temperature increases a little with the cycle number. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149155

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A temperature-programed (TP) electron-stimulated desorption ion angular distribution (ESDIAD)/time-of-flight (TOF) system was developed in order to observe surface processes in real time by ESDIAD images and to measure TOF spectra of desorbing ions for identification of the mass and the kinetic-energy distribution of ions. The instrumentation of this system is described. This system was applied to(&sqrt3;×&sqrt3;)R30°-CO/Ru(001)(0.33 ML) and CO-saturated Ru(001) surfaces. As for the(&sqrt3;×&sqrt3;)R30°-CO/Ru(001),the increase of the half width at half maximum of the ESDIAD images upon annealing was found corresponding to the thermal excitation of the bending mode and/or hindered translation. On the other hand, as for the CO-saturated surface, the static disorder of the molecular axis of CO was larger, and apparent thermal excitation was not observed. After partial desorption of CO from the CO-saturated surface where the surface changes into the&sqrt3;×&sqrt3;structure at 400–430 K, the yield ofO+increased due to the change in the adsorption site of CO. TOF spectra for ammonia adlayers(NH3andND3)were also measured by the developed system and the isotopic ratios for ESD yields depending on the adsorption states (chemisorbed first layer and physisorbed second layer) were obtained. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149156

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A high-pressure, high-temperature apparatus has been developed for the analysis of sorbents capable of removing alkali compounds to the concentration levels required by advanced, coal-fired power generating systems. The reactor is capable of operating at temperatures up to1200 °Cand pressures up to 2.0 MPa. A laser-based technique—photofragment fluorescence—enablesin situanalysis of the sodium content in a gas stream before and after a sorbent bed thereby determining the efficiency of the alkali removal by the various sorbents studied (typically alumino-silicate clays). The design and development of both the reactor and the laser-based analytical technique is described. ©1998 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1149157

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have recorded the magnetic signal generated by the human cardiac muscle with the help of a very sensitive flux-gate sensor. First, we have verified the feasibility of such detection inside a magnetically shielded room, then repeated this same experiment within our laboratory and in a low shielded environment. Results have shown the easy operation of a flux-gate sensor for this purpose and the efficiency of fast numerical processing in a low shielded environment. This leads in both cases to a voltage signal-to-noise ratio of about 5 within a 100 Hz bandwidth, which corresponds to the actual limit of the flux-gate probe.©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149158

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have measured the room temperature resonant quality factorsQfor a large set of resonant modes for each of several fused silica blocks and one fused silica cylinder. The modal frequencies ranged from 7.8 to 50 kHz. Our best results were obtained when the samples were suspended in a single loop of fine wire. For every sample tested we have measured at least one mode withQ⩾107.Our highestQfor any sample measured was(1.86±0.06)×107for a block resonating at 26.4 kHz. Our tests included several different types of high purity fused silica, but could not detect any significant differences in mechanical loss. We believe ourQmeasurements are limited by losses due to our suspensions, asQdepends strongly on the shape of each resonant mode and the proximity of each mode’s nodal regions to the wire suspension points. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149159

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We present a step-motor based cryogenic tuning device for a highQelectrical resonator. The resonator can be tuned in the 145–175 Hz frequency range. Tuning is achieved by moving a superconducting core inside the 3 H superconducting coil of the resonator. The resonator intrinsic quality factor of1.8×106is found to be unaffected by the superconducting core and by the drive system. The noise of the resonator has been measured to be thermal. The device has been developed to improve sensitivity and bandwidth performance of cryogenic resonant gravitational wave detectors equipped with resonant capacitance transducers. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149166

出版商:AIP    

年代:1998

数据来源: AIP