摘要:

An interferometric rapid-scanning autocorrelator employing two antiparallel rotating mirrors in a variable arm is optimized for maximum optical path difference as a function of the separation of the two rotating mirrors. A very compact design (mirror separation≈mirror diameter) is possible without a reduction in the maximum pulse width that can be measured. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149065

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A velocity interferometer system for any reflector, utilizing a laser of coherence length less than the optical path difference (OPD) between the two interferometer arms, is described and tested. In this instrument the laser beam is passed through the interferometer both before and after it is reflected from the target. As a result the coherence length of the laser need only be twice the relatively small distance traveled by the target in the time taken for light to traverse the OPD. Results are presented for a nonspecular target. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149066

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We complemented with data taken in transmission mode the recently described tests of the novel spectromicroscope MEPHISTO (Microscope a` Emission de Photoe´lectrons par Illumination Synchrotronique de type Onduleur). Transmitted x rays were converted by a photocathode into photoelectrons, which were subsequently electron-optically processed by the spectromicroscope producing submicron-resolution images. Test images demonstrated excellent contrast. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149067

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have commissioned a new instrument for high resolution inelastic x-ray scattering on the inelastic scattering beamline of the Synchrotron Radiation Instrumentation Collaborative Access Team on sector 3 of the Advanced Photon Source. So far, the instrument is set up at 13.84 keV with a total energy resolution of 7.5 meV and a momentum resolution of⩽0.1 Å−1.We present technical details of the instrument, which includes an in-line monochromator, a focusing mirror, and a focusing analyzer. The performance of the instrument was demonstrated in studies of phonons in diamond and chromium. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149068

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report ultrashort pulse, 1 kHz repetition rate x-ray generation in the 5–20 keV spectral region, induced by the interaction of laser radiation with copper nitrate solution and ethylene glycol liquid-jet targets. The characteristics of the copper nitrate source are relevant for application to time-resolved x-ray diffraction studies as well as for spectroscopic x-ray absorption studies. The x-ray sources were operated uninterrupted for in excess of 5 h with no detectable buildup of debris on the associated optics. The x-ray flux generated by both sources is estimated to be of the order of106 photons s−1 sr−1in the 5–20 keV region. The spectra have been measured with both a PIN photodiode, and with transmission measurements taken using aluminum filters. We find that the plasma emission has a broadband component attributed to bremsstrahlung emission, with the bulk of the x-ray emission emitted from the chamber lying between 5 and 20 keV for both sources. The copper nitrate emission, however, delivers a dominant emission peak at 9 keV, attributed to the characteristic K emission of copper. ©1998 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1149120

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A fast pulsed capillary discharge device has been developed and implemented. The device combines the features of a transient hollow cathode discharge with the inherent characteristics of the capillary discharge, to obtain VUV to XUV radiation with ns rise time. The discharge operates in a 0.8 mm inner diameter alumina capillary, at 10–30 kV applied voltage. On axis discharge initiation is assisted by electron beams, which are characteristic of the hollow cathode effect. A short, 5 ns full width at half maximum XUV pulse is produced in association with a ∼1 kA, 5 ns current pulse. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149069

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

An all fiberoptic accelerometer, based on Michelson interferometry, has been developed theoretically and experimentally. It makes use of an oscillating mass suspended by a transduction fiber in a mass support. The interferometric configuration is formed by a 3 dB single-mode fiberoptic beam splitter, on two distal endfaces of which high-reflectance aluminum films were directly coated and served as reflecting mirrors. An ac phase tracking modulation–demodulation scheme has been employed to process the signal. The performance of a prototype of the accelerometer has been investigated, and the results indicated that the measured frequency spectrum is qualitatively consistent with the theoretical prediction, and the detected output wave forms are also in good agreement with that of the applied simulation signals. In addition, the constraint on the lateral movement of the acceleration-sensitive mass with two specific diaphragms has been experimentally verified, nevertheless, it needs to be optimized further. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149070

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A versatile spectroscopic flow cell for high pressure liquids and supercritical fluid solutions is described. The cell is capable of being coupled to either standard or fiber optic spectrometers. There are two perpendicular optical paths that are adjustable in length and aperture diameter. The cell has shown it can be used for absorption, emission, or scattering spectroscopy. The design is simple, inexpensive, serviceable, uses conventional materials, and is self aligning. With apertures of 5.7 mm the cell has been tested to pressures up to 500 atm and temperatures up to 90 °C. However, the cell would allow usage at higher temperatures and pressures if desired. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149071

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The fabrication and operation of a stable and intense source of atomic hydrogen from an easily movable nozzle is described in detail. The source uses a well-known air-cooled, extended cavity microwave source using molecular hydrogen, but conducts the dissociated atoms to the experimental interaction region via inert Teflon “spaghetti” tubing. A resulting collimated beam with a dissociation fraction exceeding 0.8 and with an average number density of atomic hydrogen of6×1012 cm−3at a distance of 2 mm from the exit of the source is obtained. This source of H is attractive, because it is movable and easily interfaced into beam–beam type experiments. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149072

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

For the first time Stark experiments in a pulsed nozzle Fourier transform microwave spectrometer are successfully performed with the pulsed molecular beam parallel to the resonator axis, together with a new geometry for the Stark electrodes which prevents line broadening due toE-field inhomogeneity. The coaxially oriented beam-resonator arrangement, introduced in the 1990s, is known to provide a considerable improvement in resolution and sensitivity in comparison to the perpendicular geometry, but Stark effect experiments performed in a microwave cavity, using the conventional cubic electrode geometry with this arrangement, suffer from an inhomogeneous field distribution. This gives rise to broadened profiles of the Stark shifted lines and a persistent zero-field line. The linewidth achieved with our new configuration is now close to the typical value found in the absence of a Stark field: less than 10 kHz at 10 GHz half width at half height, which makes the system very suitable for yielding precise values of the dipole moment, a piece of chemical information especially important in understanding both structure and charge distribution of molecular complexes. The performances of the novel design electrodes and the improvements achieved are demonstrated by several examples. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1149073

出版商:AIP    

年代:1998

数据来源: AIP