摘要:

During the last 10 years various types of soft x‐ray monochromators have been developed, which are optically based on the plane grating focusing condition introduced in 1980. These instruments as well as those using the original 1980 optical configuration are reviewed and compared to the other type of high performance soft x‐ray grating monochromator, the Rowland circle based spherical grating monochromator (SGM). Performance data of a plane grating monochromator (HE‐PGM‐3), which was recently commissioned at BESSY and which offers a broad spectral range (40–2000 eV) and very high spectral resolution (up toE/&Dgr;E∼10 000) are given in more detail. The performance of grating and crystal monochromators is compared in the 1–2 keV photon energy range. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1145258

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have developed a laboratory grazing‐emission x‐ray fluorescence (GEXRF) spectrometer. The instrument utilizesinvacuowavelength‐dispersive detection. Due to the high resolution of a crystal monochromator at long wavelengths, the range of applicability of grazing x‐ray techniques is substantially extended to the longer wavelengths as compared to techniques used presently. It is demonstrated that interference fringes in the take‐off angle dependence of the fluorescent x‐ray intensity of a layered sample can be resolved using a conventional x‐ray tube. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1145250

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new method for the determination of vertical concentration profiles and its application to bilayer diffusion couples are presented. The method combines sputter sectioning techniques withexsitutotal‐reflection x‐ray fluorescence (TXRF) analysis. It allows quantitative depth‐resolved analysis of alloys consisting of elements with atomic numbers ≥13, quantitatively and depth resolved. In contrast to other surface sensitive techniques like Auger electron spectrometry or secondary ion mass spectrometry, TXRF offers the advantage of determining the sampling depth with the same instrument, so that no assumptions about sputtering rates or auxiliary measurements are necessary. With this method a depth resolution of 2.5 nm is obtained, which is comparable with the best achievable results from other depth profiling methods. Moreover, an additional TXRF scan in a nondestructive mode of operation makes a mutual comparison with the results of the sectioning technique possible. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1145260

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new and improved type of x‐ray capillary optics unit (ellipsoidal), is developed, tested, and characterized using a table‐top x‐ray microbeam setup. The beam profiles of the x‐ray beams generated by the 7.5 &mgr;m ellipsoidal capillary were constructed from ‘‘knife‐edge’’ scans across the beam. The detection limits for various elements were determined, and the spatial resolution, when the beam was used in scanning mode, was demonstrated. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1145266

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A target of gaseous polarized hydrogen was formed by injecting polarized hydrogen atoms (produced by Stern–Gerlach spin separation) into a storage cell consisting of a cylindrical tube open at both ends. The target was placed in a storage ring to study the target characteristics (nuclear polarization, target thickness, radiation resistance). A weak transverse guide field (5 G) was applied to define the polarization direction. When atoms in a single hyperfine state were selected, the nuclear polarization of the target was measured to be 0.80±0.02. The areal density of the target under these conditions was (5.5±0.2)×1013H/cm2, while for two spin states (applicable to experiments in high energy rings where a strong magnetic field can be applied to the target) the target thickness was found to be (8.2±0.3)×1013H/cm2. The target polarization was unaffected by prolonged exposure of the target to beams up to 1 mA. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146388

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a new type of radial collimator made of boron fibers. Coupled with a position sensitive detector system it is optimal for neutron diffraction studies of internal strain measurements. We show the results of the calibration and first test measurements on such a system. The obtained characteristics are excellent and allow a substantial (30) gain factor in data acquisition time. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146402

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The absolute value of refractive index and its variation with temperature of benzene and chloroform at He‐Ne laser wavelength 6328 A˚ are measured. The measurements are carried out using laser interferometric technique. This technique is based on the shift of interference pattern when rotating the sample in one arm of a newly developed Mach–Zehnder interferometer. The refractive index shows a linear relationship with temperature in the range of interest. The thermal refractive index coefficients of benzene and chloroform are all negative. Applying Maxwell’s theory and Lorentz–Lorenz function, the obtained results are used for calculating the optical permittivity (or dielectric susceptibility) as a function of temperature and many other important related physical constants. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146356

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An accurate optical distance meter that features a pulsed laser diode as a light source and two avalanche photodiodes as detectors, is reported. A cascade connection of avalanche transistors drives the laser diode to emit a periodic output pulse of 0.8 ns rise time. The photodiode rise time was found to increase whenever the incident intensity decreased below a certain threshold. Measurement errors caused by this effect were corrected by numerical processing. The optical distance meter yielded a calibration error of 0.5 mm for a white paper target placed 1 m from the laser source. The distance meter was also utilized to profile the bottom of a plastic waterpipe. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146373

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Phase fluorometry and fluorescence lifetime imaging require a source of exciting light which can be modulated at radiofrequency. This is difficult to achieve with reasonable efficiency using conventional light sources with external modulators such as Pockels cells, while laser sources are limited in wavelength tunability. In this paper a low‐cost and versatile high‐frequency modulated light source is described which is well suited to frequency‐domain fluorescence measurements. The source is a modified deuterium arc lamp which can be driven directly at frequencies up to approximately 130 MHz, and which provides a highly stable source of ultraviolet and visible light. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146325

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A microcomputer‐controlled x‐ray absorption spectrometer was built which can measure 1000 ms resolved extended x‐ray‐absorption fine structure for dynamic system of the reaction in solution. Further, we built a new stopped‐flow apparatus suitable for x‐ray absorption spectroscopy in dispersive mode. The spectrometer integrates the x‐ray absorption signals over a time interval (gate time) at any time measured from the time of sample mixing. The gate time depends on the concentration of the sample solution and the x‐ray intensity from x‐ray generator. The raw data on the time resolved‐K‐edge absorption are presented to demonstrate the feasibility of this spectrometer. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146340

出版商:AIP    

年代:1995

数据来源: AIP