bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive mode locking of lasers using bacteriorhodopsin molecules
Authors: Reddy K. P. J.
Published: July 2002

Passive mode locking of lasers using the protein molecule bacteriorhodopsin which acts as a slow saturable absorber is proposed. Based on the self-consistent approach, expressions for the laser pulse energy and pulsewidth are derived. It is shown that mode-locked pulses of 64 fs duration and 7 nJ energy could be generated in the visible region by this method.
Epitaxial layer transfer by bond and etch back of porous Si
Authors: Yonehara Takao , Sakaguchi Kiyofumi , Sato Nobuhiko
Published: July 2002

We demonstrate a novel method for bond and etch back silicon on insulator in which an epitaxial Si layer over porous Si is transferred onto a dissimilar substrate by bonding and etch back of porous Si. The highest etching selectivity (100 000:1) between the porous Si and the epitaxial layer is achieved by the alkali free solution of HF, H2O2, and H2O which is essential for this single etch-stop method to produce a submicron-thick active layer with superior thickness uniformity (473±14 nm) across a 5 in. silicon-on-insulator wafer.
Optical anisotropy and spin polarization in ordered GaInP
Authors: Wei Su-Huai , Zunger Alex
Published: July 2002

Spontaneous CuPt-like ordering of GaxIn1−xP causes a splitting at the valence band maximum (VBM) and induces an anisotropy in the intensities of the transitions between these split VBM components and the conduction band minimum. We calculate these intensities as function of ordering parameter η, and show that the transition intensities depend strongly on the light polarization ê and the degree of long-range order η in the sample. Furthermore, for sufficiently ordered single-subvariant sample, 100% spin polarization of emitted photoelectrons is predicted.
Crosstalk in dynamic optical interconnects in photorefractive crystals
Authors: Andersen Peter E. , Petersen Paul M. , Buchhave Preben
Published: July 2002

We have investigated the crosstalk between two neighboring gratings in photorefractive Bi12SiO20 optical interconnects. The gratings are induced by the interference between one reference beam and two object beams. By applying a suitable phase shift in one of the object beams, we can selectively switch off one of the gratings. The crosstalk between the two gratings is experimentally determined from the diffraction efficiency in the remaining grating before and after applying the phase shift. The magnitude of the crosstalk is determined by the intensity ratio between the reference beam intensity and the object beam intensity. Crosstalk can be avoided by choosing a certain intensity ratio between the reference and the object beams.
Improved crystalline quality of AlAsxSb1−x grown on InAs by modulated molecular-beam epitaxy
Authors: Zhang Yong-Hang , Chow David H.
Published: July 2002

This letter reports a dramatic improvement in crystalline quality of AlAs0.16Sb0.84 ordered alloys compared with random ones grown by modulated molecular-beam epitaxy (MMBE) on InAs substrates. The average As/Sb ratio in these ordered alloys is accurately controlled by the modulation of As2 and Sb2 beams. The surface morphology of the epilayers is mirrorlike to the naked eye and appears texture- and cluster-free under an electron scanning microscope. X-ray diffraction measurements reveal that the lattice-matched conditions for AlAsxSb1−x epilayers to InAs can be easily achieved by simply changing the As-shutter dutycycle. Distinct satellite peaks corresponding to the ordered structure with a period of about 11 Å are also clearly observed. Strong photoluminescence (PL) is observed from GaAs0.08Sb0.92/AlAs0.16Sb0.84 single quantum well structures up to room temperature under a very low photoexcitation (5 W/cm2). At 5 K the PL linewidth is 4.5 meV.
Diamond film growth in low pressure premixed ethylene-oxygen flames
Authors: Kim J. S. , Cappelli M. A.
Published: July 2002

A study of diamond film synthesis in low pressure premixed ethylene-oxygen flames is described. Experiments are performed in a low pressure flat-flame facility that has been employed previously to study diamond synthesis in premixed acetylene-oxygen flames. High film quality and uniformity are observed for substrate temperatures of approximately 700 °C and flame equivalence ratios of 2.41. There exists a distinct range in flame equivalence ratios for high quality diamond deposition that is comparable to that seen in acetylene-oxygen mixtures. The measured diamond growth rates are approximately one-quarter of that observed for acetylene-oxygen flames. However, when factoring in differences in the operating conditions, carbon utilization is approximately one-half of that observed for premixed acetylene-oxygen flames.
Effect of ultraviolet light on fatigue of lead zirconate titanate thin-film capacitors
Authors: Lee J. , Esayan S. , Safari A. , Ramesh R.
Published: July 2002

Fatigue of Pb(Zr0.52Ti0.48)O3 (PZT) thin-film capacitors was studied under UV light (He-Cd laser, λ=325 nm). The remanent polarization of the PZT film capacitors increased upon light illumination. Fatigue resistance was also improved under UV light. During fatigue test, the change in polarization of PZT films upon UV light illumination increased gradually with cycling. These results were examined within the framework of the polarization screening model, which is suggested as an essential process for fatigue. This leads to a conclusion that more charged defects are involved in the fatigue process through internal screening of polarization.
Direct observation of hexagonal boron nitride at the grain boundary of cubic boron nitride by high resolution electron microscopy
Authors: Zhou Wei-Lie , Ikuhara Yuichi , Murakawa Masao , Watanabe Syuichi , Suzuki Tetsuya
Published: July 2002

Cubic boron nitride (c-BN) film deposited on a Si substrate was observed by high resolution electron microscopy. Thin layers, 1–2 nm, of hexagonal boron nitride (h-BN) phase were often found at the boundaries of c-BN grains. The observed interplanar spacing was about 0.33 nm, which coincided with that of the (0002) plane of h-BN. The nucleation mechanism of c-BN film is briefly discussed based on the formation of the h-BN phase at the grain boundaries. The existence of the h-BN phase at the boundaries of c-BN grains may be the reason for the occurrence of compressive stress and cracks in c-BN thin films.
Low temperature epitaxial silicon film growth using high vacuum electron-cyclotron-resonance plasma deposition
Authors: DeBoer Scott J. , Dalal Vikram L. , Chumanov George , Bartels Randy
Published: July 2002

We report on the growth technique and electrical properties of epitaxial Si films grown at low temperatures using an electron-cyclotron-resonance plasma deposition technique. We have used standard high vacuum apparatus to grow high quality films at 450–525 °C. A critical step in achieving high quality films is an in situ hydrogen plasma cleaning of the wafer before growth. We have systematically studied the influence of ion bombardment during growth by biasing the substrate, and find that the films are crystalline for substrate bias voltages less negative than about −15 V, but become polycrystalline as the magnitude of the negative bias is increased. The crystallinity of the film was measured using Raman spectroscopy. The undoped films are n type with carrier concentrations in the 1016–1017 cm−3 range. The Hall mobilities measured for the films are comparable to values obtained in bulk Si crystals. We can achieve abrupt profiles in carrier concentrations between the heavy doped substrate and the epilayer, with no evidence of diffusion.
Study of InAlAs/InGaAs heterojunction bipolar transistor layers by optically detected cyclotron resonance
Authors: Chen Y. F. , Shen J. L. , Dai Y. D. , Jan G. J. , Lin H. H.
Published: July 2002

We report an investigation of optical and electronic properties in InAlAs/InGaAs heterojunction bipolar transistor layers by optical detection of cyclotron resonance (ODCR). Strong ODCR spectra structured by quantum oscillations have been observed, from which the effective mass and the carrier concentration of the two-dimensional electron gas can be obtained. The measured cyclotron mass is heavier than the conduction-band-edge mass in bulk InGaAs. We find that the carrier concentration increases with the spacer thickness. Quite unexpectedly, we also find that the effective mass increases with decreasing the carrier concentration.
Temperature dependence of photoluminescence lifetimes in ordered GaInP2
Authors: Thomeer R. A. J. , Driessen F. A. J. M. , Giling L. J.
Published: July 2002

The temperature dependence of carrier lifetimes in ordered (o) GaInP2 epilayers was investigated with and without cladding layers of disordered (d) GaInP2. The extremely long lifetime of the emission that moves with laser excitation density and the shorter lifetime of the nonmoving emission persist up to T=50 and 300 K, respectively. Both decays involve localized holes. By removal of the d top layer of the double heterostructure, an enhanced hole diffusion to the surface occurs, which results in a slightly faster, nonexponential decay. It is argued that, within the nominally o layer, a type II recombination occurs and that o and d GaInP2 exhibit a type II band lineup. The appropriate band curvatures in the d top layer cause hole localization at the d side of the o–d interfaces. The minority carrier lifetime shows two-dimensional behavior between T=70 and 170 K, and decrease above 170 K.
Assessment of beam intensity profiles in an iodine laser using optical fibers
Authors: Raffo C. A. , Rebollo M. A. , Doti R.
Published: July 2002

A method has been developed for measuring the spatial profile of the output beam of an iodine laser at 1.315 μm, which requires only using two optical fibers, one for collecting a reference signal and the other for detecting the laser intensity at a given point of the wavefront. The precision is sufficient for laser engineering purposes.
Fourier transform microwave spectrometer using an electric-field cross-correlation technique
Authors: Ramsey J. M. , Whitten W. B.
Published: July 2002

An electric-field cross-correlation technique is described which can be used for measuring microwave rotational absorption spectra and which has a wide range of applications in other areas. The spectrometer is a novel implementation of a Michelson interferometer. The wide bandwidth source is obtained by modulating a single-frequency signal with a pseudorandom binary sequence. The variable phase delay for determining the cross-correlation function is obtained synthetically from an identical but out-of-phase pseudorandom sequence. The spectrometer operates at X-band frequencies with a bandwidth of ≂100 MHz and a resolution of ≂100 kHz. The J=1←0 transition of 16O12C32S was observed.
KSU project: CRYEBIS for producing slow, bare, heavy-ion beams
Authors: Stöckli Martin P. , Cocke C. Lewis
Published: July 2002

The design and construction of a cryogenic electron beam ion source is in progress at Kansas State University. In about two years this source should produce high yields of bare and few-electron argon ions with low kinetic energies (∼keV–MeV). The design is similar to the latest French designs {CRYEBIS II [J. Arianer, C. Goldstein, H. Laurent, and M. Malard, IEEE Trans. Nucl. Sci. NS-30, 2737 (1983)] and DIONE [B. Gastineau, J. Faure, and A. Courtois, Nucl. Instrum. Methods B9, 538 (1985)]}. However, several significant changes were incorporated in order to get a simpler and more flexible design. The key factors of the operation which are expected to limit the performance are discussed. The general design is outlined which allows significant future upgrading to obtain nongaseous as well as much heavier, highly ionized ions.
Inexpensive, portable, digital data logger
Authors: Morgan F. D.
Published: July 2002

An A/D converter has been interfaced to an Epson HX-20 computer to log geophysical data.
Influence of the vibrating system of a multipinhole-plate ultrasonic nebulizer on its performance
Authors: Maehara Naoyoshi , Ueha Sadayuki , Mori Eiji
Published: July 2002

A multipinhole-plate ultrasonic atomizer was experimentally optimized, employing a bender bimorph vibrator structure made up of a thin pinhole plate and a circular ring piezoelectric element. Effects of the vibration mode upon the performance were studied in terms of the sound pressure generation and the behavior of bubbles caused by cavitation. The performance was also examined with regard to the number of pinholes and the shape of the pinhole plate. As a result, the atomizer was proved to be able to jet and nebulize ordinary liquid most efficiently by the second harmonic vibration mode if the vibrating system is supported along the circumference of the ring piezoelectric element. It was also proved that the maximum atomizing rate is approximately proportional to the number of pinholes and that the spray pattern can easily be controlled by changing the shape of the pinhole plate.
Influence of the scattered electrons from the interchannel web of a multichannel-plate detector on the resolution and the background of an electron energy analyzer
Authors: Franchy R.
Published: July 2002

The background of an electron energy analyzer with a position-sensitive detector based on microchannel plates is reduced by installing a biased grid in front of the channel plate. The scattered electrons from the interchannel web of the detector are removed when the grid is positively biased with respect to the face of the channel plate.
Self-balancing resistance bridge
Authors: Kaplan Alvaro , Zimmerman George O. , Edmonds Dean S.
Published: July 2002

An automatically balanced resistance bridge with below-picowatt dissipation in the measured resistance has been developed. The bridge, capable of measuring resistances between 20 Ω and 10 kΩ with an accuracy of 5%, was specifically designed to allow resistance measurements to be made at low temperatures without introducing an appreciable heat source to the cryostat. It consists of a Wheatstone bridge having a photoresistor as one of its arms. The feedback balance is accomplished by means of light-emitting diodes which control the photoresistor. A novel feedback principle used in the bridge is described.
RACETRACK: Novel device for basic research on magnetized plasmas
Authors: Kuthi A. , Zwi H. , Schmitz L. , Chelf D. , Wong A. Y.
Published: July 2002

The construction and operation of a novel magnetized plasma device are described. The device combines characteristics of both linear mirror and toroidal confinement. It opens up new areas of basic plasma physics research. Examples of experiments on potential formation are presented.
System for investigating the response of piezoelectric solids to large cyclic stresses
Authors: Amin Ahmed
Published: July 2002

A system for investigating the elastoelectric response of piezoelectric solids to large cyclic stresses is described. System architecture, computer control, and examples of the system output are given.
Detection of clustered H2 at 4.2 K
Authors: Graebner J. E.
Published: July 2002

A special calorimeter is described which is capable of detecting molecular hydrogen trapped in solid material. It takes advantage of the energy released by the slow ortho–para conversion of H2 after rapid cooling from room temperature to 4.2 K. The technique is simple, quantitative, and nondestructive, and can be used on any nonmagnetic host with a sensitivity of ∼1017 H2, or typically 1 ppm for a 1-cm3 sample. The rate of decay also gives information about the local configuration of the H2. Data are presented for H2 clustered in 50-Å-diam microvoids in films of electroless deposited Cu.
Convenient measurement of small impulses
Authors: Brost G. , Deaton T. , Duvall B. , Boyle W. , Tinsley J. , Bohn C. , Stephen M. , Souders J.
Published: July 2002

This paper describes a convenient method which has been used for the measurement of small impulses (1–20 dyn s). An inductive displacement gauge was used to monitor displacement of a ballistic pendulum.
Long-path absorption cell for use with condensable samples
Authors: Bragg S. L. , Wiswall C. E.
Published: July 2002

A small-volume long-path absorption cell has been designed for use with condensable samples. The absorption cell is temperature controlled and operates over the temperature range of −10 to 80 °C. To prevent condensation of the sample on the mirror surfaces, the mirrors are individually temperature controlled and maintained a few degrees above the ambient temperature of the absorption cell. The cell has been tested and used to measure weak absorptions in water vapor in the near infrared.
Novel method for stabilizing the optical output of pulsed light sources
Authors: Yamashita Mikio
Published: July 2002

A method for stabilizing the optical output of pulsed light sources is described that uses a unique optical feedback loop. The method can assure an excellent stability of the optical output, and offers the advantage that it can be applied to a broad range of optical intensity. Stability tests of a pulsed light source using a GaP green light-emitting diode (LED) stabilized by the proposed method are also described.
Response of a Fabry–Perot cavity to phase modulated light
Authors: Hils Dieter , Hall J. L.
Published: July 2002

We present a solution to the lock-in detection method which is valid for arbitrary values of the modulation frequency. Our solutions agree with the results of the quasistatic theory, in the limit of small modulation frequency compared to the resonance linewidth.
Inexpensive and versatile computer interface for an EPR spectrometer
Authors: Giugliarelli G. , Tancini P. , Cannistraro S.
Published: July 2002

A computer interface for an EPR spectrometer is based on the IEEE 488 standard and is controlled by the HP86A.
New apparatus for studying fatigue deformation at high magnifications
Authors: Stephens Robert R. , Hoeppner David W.
Published: July 2002

One of the steps taken to enhance accurate fatigue life estimations and material modeling is the development of an electrohydraulic, servo-controlled feedback fatigue apparatus that has been joined to a scanning electron microscope. This apparatus allows in situ observations of cyclically loaded specimens undergoing fatigue deformation. Using this apparatus, recordings can be made of the events related to the surface response of materials under different loading conditions, showing how microstructural features influence crack nucleation and propagation behavior. With the development of this apparatus, existing mathematical models describing the fatigue process can be enhanced or improved, and more accurate fatigue life estimation methods can be obtained. The apparatus developed is described herein, as well as a few selected results.
Measurement of large displacements of the toroidal current centroid using an external coil diagnostic
Authors: Che H. Y. , Ivers T. H. , Mauel M. E.
Published: July 2002

Several sinusoidal and saddle coils have been used to measure the toroidal current centroid of discharges produced in a pulsed tokamak experiment. Careful analysis of the external coil measurements and elaborate calibrations made the measurements possible even for large displacements of the plasma current and the noncircular geometry of the diagnostic coils. The calibration techniques and the data analysis formula are described, and examples of the use of the external coils to measure m=1 kinks of unstable toroidal Z-pinch discharges are presented.
High-pass bird-cage coil for nuclear-magnetic resonance
Authors: Watkins Joel C. , Fukushima Eiichi
Published: July 2002

Cylindrical bird-cage coils generate uniform magnetic fields transverse to the cylinder axis for use in the large sample nuclear-magnetic resonance (NMR) experiments. We describe the design and construction of an eight-rung high-pass bird-cage coil to operate at 80 MHz in a cylindrical bore of a superconducting magnet. The coil is 12.7 cm in diameter by 30.5 cm long and has a 7-cm-diam region in the center where the field intensity is within 10% of the average.
Sensitivity improvement of a Varian E-109 EPR spectrometer with a low noise microwave amplifier
Authors: Dexheimer S. L. , Klein M. P.
Published: July 2002

The installation of a low noise GaAsFET microwave preamplifier into a Varian E-109 homodyne X-band EPR spectrometer is described, and measurements of the resulting improvement in sensitivity as a function of microwave power are presented. Particular attention is paid to modification of the automatic frequency control (AFC) system to compensate for the preamplifier gain, which would otherwise result in instability of the AFC servoloop and decreased spectrometer performance at moderate microwave power levels. Specific details are provided for modification of the Varian E-102 bridge, but the general approach is applicable to other spectrometers.
Optical spectroscopy at cryogenic temperatures using a Block–Piermarini diamond-anvil cell
Authors: Leroux M. , Leymarie J. , Méheut G. , Neu G.
Published: July 2002

A simple experimental setup allowing low-temperature high-pressure spectroscopy, with in situ pressure adjustment, is described. A Block–Piermarini diamond-anvil cell is used together with standard laboratory materials. Results of semiconductor photoluminescence studies, using argon as a pressure-transmitting medium, are given as an illustration and are also used for the study of the pressure conditions. Pressure homogeneity is better than 100 MPa up to 6 GPa, and the residual uniaxial component of the stress can be lower than 100 MPa.
High-accuracy oxygen polarograph for photosynthetic systems
Authors: Meunier P. C. , Popovic R.
Published: July 2002

A new system is presented here, whose design is based on the electrochemical phenomena occurring on the platinum electrode that we examined before [P. Meunier and R. Popovic (unpublished)]. The architecture of the system is articulated around an IBM-PC computer which controls the polarization of the electrodes, the triggering of the flash lamp, and the acquisition of data. The potentiostat circuit and new electrode design improve the response of the electrode to a rise time of 4 ms and a decay time constant of 21 ms, without the signal being distorted by filters and without using the first derivative of the signal. This polarograph shows a 50-dB signal-to-noise ratio (0.3% error) during experiments with the motile algae Dunaliella tertiolecta. The determination of amplitudes of oxygen production is performed with third-order cubic spline interpolations, after subtraction of the current base line. The resulting accuracy and reproducibility will enable researchers to attain a higher degree of refinement in the quantification of properties of the oxygen evolving complex.
Simple, externally triggered filter changer
Authors: Basak Soumen , Ferrone Frank A.
Published: July 2002

We describe a simple, mechanical device to interchange two optical filters rapidly upon external command. The device has two stable points, eliminating backlash and step counting problems.
The new(?) wave: Digital lock-in amplifiers
Authors: Rubin L. G.
Published: July 2002

The digital lock-in amplifier, implemented by either hardware or software, is not a recent development. Evidence to this effect is provided by examples of publications spanning the past 20 yr.
New densimeter for cryogenic fluids by magnetic levitation of a high-T
c superconductor
Authors: Fujii K. , Takenaka M. , Nara K.
Published: July 2002

A new magnetic densimeter for cryogenic fluids has been developed by adapting a magnetic levitation of a high-Tc superconductor. In this instrument, a superconducting material made of Y–Ba–Cu–O is sealed in a hollow glass buoy, and a stable levitation of the buoy is carried out with the Meissner effect of the superconductor simply by placing the buoy in the fluid above a ring-shaped permanent magnet. The fluid density is obtained from the magnetic force required to levitate the buoy in the fluid. To measure this force, the magnet is suspended from an electronic balance and the reaction force acting on the magnet is determined directly as a change of the apparent weight of the magnet. Details are given of the theoretical calculation of the force acting on the superconductor in the magnetic field and of the construction of the apparatus. The measurements of the saturated liquid density of nitrogen have shown a standard deviation of 0.014%. The total uncertainty of the measurements is estimated to be less than 0.06%. The results agree with reliable literature values within the experimental uncertainty.
Para-flex stage for microtopographic mapping
Authors: Teague E. Clayton , Young Russell D. , Scire Fredric , Gilsinn David
Published: July 2002

The design and performance of a high-precision X–Y stage which uses a unique type of flexure pivots is described. Performance achieved with a symmetrical arrangement of four arm/pivots for each axis is such that pitch, roll, and yaw is less than one arcsecond for 1×1-mm stage motion. Vertical vibration during stage motion is less than 2.5 nm peak to valley, with the major limitation being insufficient decoupling from the drive mechanism. Also described is the application of the stage for performing microtopographic mapping with a stylus transducer.
Energy-modulated x-ray microtomography
Authors: Kinney John H. , Johnson Quintin C. , Saroyan R. Allyn , Nichols Monte C. , Bonse Ulrich , Nusshardt Rudolf , Pahl Reinhardt
Published: July 2002

We describe an instrument for computerized x-ray tomography which can provide fully three-dimensional examination of small samples (a few millimeters to a few centimeters) with resolution variable from 5 to 100 μm. Elemental and chemical-state distributions are obtained with high resolution by modulating the energy of the incident x-ray beam. An essential component is the monochromator we designed and optimized for chemical microtomography. It has a narrow energy bandpass and a large degree of harmonic suppression, provides a uniform x-ray beam with small angle of divergence, and is cooled in a way that eliminates thermal and vibrational instabilities.
Measurement of interfacial dilational properties: A software-driven apparatus
Authors: Loglio Giuseppe , Tesei Ulisse , Cini Renato
Published: July 2002

The construction of a time-resolved surface viscoelastometer for the study of fluid/fluid interfaces is described in detail. Instrument design and operation are based on the formalism of systems theory. An interfacial-area change (i.e., an external stimulus) is generated according to a given time function; the ensuing dynamic surface tension response is continuously recorded in synchronism with the stimulus. The principal characteristic of the equipment is a computer-controlled mechanical motion of the area-confining device (i.e., of a particular ring barrier, in place of the traditional linear barriers). The software allows a wide variety of oscillatory or transient experiments to be conducted. Instrument performance is illustrated by a typical experimental response, obtained under conditions of small-amplitude area perturbation, for a submicellar aqueous solution of surfactant. The recorded trace is fitted to a theoretical two-parameter model. Results show the effectiveness of the controlled-surface-deformation technique, allowed by the instrument, for determining static and dynamic interfacial properties.
Approximation of the nonparalyzable dead time by the shortest time interval
Authors: Sabol J.
Published: July 2002

The method based on the approximation of nonparalyzable dead time by the shortest time interval between two successive pulses at the output of the radiation detection system or any other system for processing and counting random event trains has been proposed and investigated.
Time-of-arrival digital photon correlator
Authors: Singh B. P. , Chopra S.
Published: July 2002

Design and fabrication of the R 6501 microprocessor-based photon correlator, equally applicable to Gaussian as well as non-Gaussian radiation, is described. It works on the principle of directly registering the arrival times of photoelectrons.
Use of a frequency convertor in microwave hypersonic attenuation measurements
Authors: Vanreyten N. , Michiels L. , Mangelschots I.
Published: July 2002

We describe how a frequency convertor in a microwave system reduces the interference problem in hypersonic attenuation measurements on samples which display a temperature-dependent sound velocity.
Critical assessment of fluorescence polarization measurements with a FACS IV cell sorter
Authors: Muller Claude P. , Krabichler Gert
Published: July 2002

The usefulness and limitations of the Becton–Dickinson fluorescence-activated cell sorter FACS IV for fluorescence polarization measurements were examined. A set of tests to determine the characteristics of the detection geometry, the optical properties of the beam splitter, and the capability to process fluorescence polarization data is presented. Recommendations are provided for correcting instrumental deficiencies.
Automated system for measurement of the effective surface-charge decay rate of unshielded electrets
Authors: Clator Irvin G.
Published: July 2002

A rotating probe assembly suitable for effective surface-charge decay-rate measurements is described. Utilizing computer acquistion of data, low resolution charge distribution measurements can be made.
Simple interface between electrochemical systems and FTIR spectrometers
Authors: Holze R. , Freisenich U. , Stach W.
Published: July 2002

An electronic interface connecting the potentiostat of an electrochemical measurement system to a Fourier transform infrared (FTIR) spectrometer as used for in situ IR reflection absorption studies is described. It makes use of readily available components, is installed without any changes in the hardware of the spectrometer or the potentiostat, and allows fast and reliable spectroelectrochemical measurements.
Simple method of measuring vibration amplitudes at better than nanometer sensitivity
Authors: Greaves T. J. , Curzon F. L.
Published: July 2002

It is shown that vibrations driven at fixed frequencies of a few kilohertz can be studied, with displacement sensitivities in the nanometer range, by thermally modulating the length of one arm of a Michelson interferometer, and analyzing the photomultiplier output with a sampling oscilloscope and a spectrum analyzer. This method of measurement has the advantage that the high sensitivity can be attained without a constant temperature enclosure for the interferometer.
Applications for an ultraprecise mass spectrometer requested
Authors: Koets E.
Published: July 2002

A mass spectrometer with a potential error in the 10−12 range (i.e., 1 meV/amu) is inactive now. The machine will be scrapped soon, unless suitable applications (and funding) are found or an interested institute acquires the instrument.
Laser optical pumping of rare-gas metastable atom beams
Authors: Butler W. H. , Hammond M. S. , Lynn J. G. , Dunning F. B. , Walters G. K.
Published: July 2002

Time-of-flight techniques are used to demonstrate the very high rare-gas metastable atom polarizations that can be achieved in a beam through optical pumping with a simple frequency-modulated multimode dye laser.
Large-aperture, axially symmetric ion-optical lens systems using new types of electrostatic and magnetic elements
Authors: Liu W. Z. , Becchetti F. D.
Published: July 2002

We have developed new types of ion-optical systems having larger solid angles (i.e., collecting power) and flexibility than many existing designs. They use relatively simple axially symmetric elements, namely solenoids, axial magnetic dipoles, and radial electric field lenses. The systems can focus, with good optical properties, energetic ions in the range of tens of keV up to tens of MeV kinetic energy and are capable of operating in nondispersive, achromatic modes. The key elements for the latter are new types of defocusing magnetic and electrostatic correction lenses. The lens systems have applications in any existing devices used to collect and focus energetic ions (including electrons). Typical devices are: mass spectrometers, leak detectors and gas analyzers, ion sources, accelerators and ion implantation systems, nuclear particle spectrometers, electron microscopes, ion microprobes, and ion-beam lenses for cancer therapy.
Determination of the magnitudes and signs of flow parameters by hot-wire anemometry. Part I. Measurements using hot-wire X probes
Authors: Acrivlellis Michael
Published: July 2002

Using two commercially available hot-wire X probes, a conventional measurement technique, and the evaluation method described here, the magnitude of the time-averaged velocity vector and the magnitudes of the Reynolds normal stress components as well as the magnitudes and signs of the Reynolds shear stress components can be determined. The evaluation method employs as a basis the spatial directional sensitivity of hot-wire probes and involves the squaring of the anemometer’s output signal. Furthermore, the region of applicability of this method is discussed.
New accessory for strongly scattering samples in Fourier-transform infrared spectroscopy
Authors: Kaihara Mikio , Mametsuka Hiroaki , Gunji Naoki , Gohshi Yohichi
Published: July 2002

The Fourier-transform infrared (FTIR) spectra of pitches or any other strongly scattering samples have large backgrounds. The existence of a large background reduces the accuracy when analyzing the spectrum. Many researchers have tried to reduce the backgrounds by crushing strongly scattering samples as minutely as possible. However, even though the size distributions were less than 10×10−6 m, the spectral backgrounds of pitches were only slightly reduced. The problem remains unresolved. The large background appears because optical compensation between the sample side and the reference side in the IR spectrometer is insufficient from a spectroscopic point of view. Therefore, new dilution materials were proposed for recovering the true meaning of compensation by scattering both the sample and the reference uniformly in our laboratory. However, our method had a problem, i.e., the IR rays reaching the IR detector were attenuated because of the scattering effect of the new dilution materials. To solve this problem, we fabricated a pair of ellipsoidal mirrors and combined new dilution materials together. The spectra measured by our new instrument possess remarkably fine qualities for strongly scattering samples.
Automated sample transport system for chromatography/secondary ion mass spectrometry
Authors: Duffin Kevin L. , Flurer Rick A. , Busch Kenneth L. , Sexton Larry W. , Dorsett John L.
Published: July 2002

The design of a new sample cell for a large-scale secondary ion mass spectrometer is described. Unique to this new source chamber is the incorporation of large piezoelectric translator stages capable of 20 cm×20 cm movement with high resolution. In addition, the source chamber is designed so that interchangeable detector assemblies can be fitted to the chamber.
An improved correction algorithm for number density measurements made with the Forward Scattering Spectrometer Probe
Authors: Lock James A. , Hovenac Edward A.
Published: July 2002

A correction factor to the number density measured by the Forward Scattering Spectrometer Probe (FSSP) which compensates for dead time and coincidence errors was determined by calculating the probabilities of and the average number of particles in the six possible types of dead time and coincidence events. These probabilities and averages were calculated by means of a probabilistic model based on Poisson statistics. A Monte Carlo computer simulation of the FSSP operation was also carried out and the number density correction factor was compared with the Monte Carlo data. For an actual number density of 2000/cm3, it was found that the measured number density was of the order of 300/cm3.
Quartz crystal microbalance thin-film dissolution rate monitor
Authors: Hinsberg William D. , Kanazawa Kay K.
Published: July 2002

We describe the details of construction and operation of an instrument useful for the characterization of dissolution kinetics of thin films. This device, based on a quartz crystal microbalance operating in contact with a liquid, avoids the limitations associated with the use of optical, electrical, and mechanical dissolution rate measurement techniques. The QCM rate monitor has general application to the measurement of the kinetics of dissolution of transparent and opaque thin films such as dielectrics, metals, and polymeric resists.
Coupling coefficient information from the linac-mode spectrum
Authors: Shanker O. , Rai Chowdhuri P. A. , Verma R.
Published: July 2002

We present methods to extract the values of intercavity coupling constants for a biperiodic linac chain from the measured mode spectrum. By making use of the form of the dispersion relation and reformulating the problem, we manage to get analytically soluble equations. As a result, our solutions do not require guess values for initiation of iterations unlike in the case of numerical fitting, and we show that the least-squares fitting gives more than one set of solutions.
Photoemission studies of Si(100) oxidation process (abstract)
Authors: Nakazawa M. , Kawase S. , Sekiyama H.
Published: July 2002

Photoemission spectroscopy using synchrotron radiation is a powerful tool to investigate electronic states of solid surfaces. In the present study, the oxidation process of the Si(100) surface has been extensively examined. Experiments were carried out with soft x-rays monochromatized by the grazing incidence monochromator,1 at beamline 8A at the Photon Factory. The energy resolution, including both the electron energy analyzer (a double-pass type CMA) and the monochromator, was estimated from the Au Fermi edge. The Au foil was sputter cleaned by Ar ions. For the photon energy between 40 and 200 eV, the resolution is about 0.3 eV with electron pass energy of 10 eV and monochromator exit slit width of 10 μm. The oxidation process of a Si(100) surface has been examined in situ at the base pressure of 5×10−8 Pa. The Si(100) clean surface is obtained by repeating Ar ion sputtering and annealing. We have measured the Si 2p photoelectron spectra of the Si(100) surface exposed to oxygen. At the early stage of 20–1000 ℓ oxygen exposure at room temperature, outermost Si atoms are partially oxidized and an energy shift of 1–2 eV is observed. The oxidation proceeds much faster when the surface is heated at 300–400 °C during oxygen exposure. In this case, three intermediary components (SiOx x<2) and SiO2 are detected. By further oxidation (104 ℓ oxygen exposure) at 700 °C, a thin SiO2 layer is formed. In addition, valence band and Si L2,3 XANES spectra have been taken for the surface. The results support the oxidation process clarified by the present method.
Real time K-edge subtraction x-ray imaging
Authors: Fukagawa Hiroshi , Noda Chosaku , Suzuki Yoichi , Hasegawa Shin , Ando Masami , Hyodo Kazuyuki , Nishimura Katsuyuki , Akisada Masayoshi , Takenaka Eiichi , Hosaka Ryosuke , Toyofuku Fukae
Published: July 2002

This paper describes an x-ray K-edge subtraction television system for noninvasive angiography utilizing synchrotron radiation. The phantom, including contrast material (iodine), is irradiated by monochromatized dual-energy x-ray flux, alternately, using a high speed monochromator. The monochromator consists of a silicon crystal plate vibrating at 15 Hz so that the phantom is irradiated by the x-ray flux of 150 eV above and below the K-edge photon energy of iodine, 15 times per second. As an x-ray detector, TV cameras optically coupled to an x-ray image intensifier are used and the video signal is processed to display the subtraction image of pairs of successive images in real time. This system was fully implemented and moving phantoms were examined. Both the time interval between the energy change and the exposure time of each image has been shortened to 2 ms.
Spin resolved vacant state spectroscopy by means of x-ray resonance magnetic scattering (invited) (abstract)
Authors: Namikawa K.
Published: July 2002

X-ray resonance magnetic scattering (XRMS) is a combined effect of a spin-dependent electromagnetic interaction and a spin polarization of the intermediate state in resonance. The first observation of XRMS, which was performed by the present author and his co-workers, was concerned with Ni K-shell electrons. Information derived from that experiment was therefore restricted to the polarization of the p-type density of states above the Fermi level. In the present work, however, XRMS from Gd has been observed near the L absorption edge. The spin polarization spectrum relevant to the unoccupied d-type density of states has also been investigated. Owing to a high value of d-band density of states and its high polarization and also to large value of atomic scattering factor, the asymmetrical ratio of XRMS, (I↑−I↓)/(I↑+I↓), amounts to several percent at the maximum by contrast with the value of 1×10−3 for the case of Ni. The majority spin of Gd d band is found to be in excess at approximately 2 eV above the Fermi level and the minority spin in excess at approximately 8 eV above the Fermi level. The results derived from XRMS are compared with the results of a band theory calculation. Both temperature and magnetic field dependencies of the asymmetrical ratio are also discussed.
Optical klystron experiments at Orsay on Super-Aco and prospects in the VUV (invited)
Authors: Prazeres R. , Bazin C. , Bergher M. , Billardon M. , Couprie M. E. , Ortega J. M. , Velghe M. , Petroff Y.
Published: July 2002

This paper consists of a general presentation of the Storage Ring FEL activities at LURE (Orsay). We first summarize the results obtained previously with an optical klystron installed on the ACO storage ring, and then make a presentation of the different projects that have begun on the new storage ring Super-ACO. The ACO storage ring experiments were of two kinds: the Free Electron Laser oscillator (FEL), and the coherent harmonic generation (CHG). The first allowed us to reach the visible spectral range, between 6500 and 4600 Å. In the second, we were able to produce coherent emission in the VUV: it was the shortest wavelengths (1773 and 1064 Å) ever obtained with an optical klystron or an undulator acting as a nonlinear medium. In this last configuration, the fundamental wave was an external pulsed and doubled Nd-Yag laser, focused in the optical klystron. The new Super-ACO storage ring has been equipped with a new optical klystron. The first ‘‘spontaneous emission’’ spectra have been observed and they show that the performance is in good agreement with theoretical predictions. FEL oscillator experiments in the visible range are planned for the end of the year. In parallel, CHG experiments in the VUV will begin.
Operation of a five-pole superconducting wiggler in the DCI positron ring and design of the beamline (invited)
Authors: Bazin C. , Dubuisson J. M. , Labéque A. , Level M. P. , Raoux D. , Sommer M. , Zyngier H. , Chomillier J. , Frouin J. , Garreau Y. , Loupias G. , Tarbes J.
Published: July 2002

A five-pole superconducting wiggler has been installed in the DCI positron ring and operated without disturbing the machine characteristics at full energy (1.85 GeV) and maximum current (300 mA). Three beamlines have been built which feed six beam ports. The first two-crystal monochromator to be used for Compton scattering has been commissioned although the sagittal focusing has not yet been tested.
Low-cost microcomputer control of multiplexing during Auger analysis of thin films
Authors: O’Connor T. E. , Windsor N. R. , Schreifels J. A.
Published: July 2002

A simple inexpensive peak detector circuit is described that permits the calculation of peak-to-peak heights during Auger analyzed depth profiles of solid surfaces. This circuit is interfaced with and controlled by a microcomputer where data can be stored and subsequently analyzed.
Modified heat-pulse technique for high-resolution specific heat measurements
Authors: Dixit R. N. , Pattalwar S. M. , Shete S. Y. , Basu B. K.
Published: July 2002

We have modified the standard heat-pulse method using digital techniques to measure the heat capacity of small samples (100–200 mg) with a resolution of better than 0.2% in the temperature range of 77–300 K. In this note, we describe fully the technique and the instrumentation. Some of the results obtained with high Tc superconducting samples are also reported.
Conversion of the SRS to a higher brilliance lattice (invited)
Authors: Thompson D. J. , Suller V. P.
Published: July 2002

The SRS at Daresbury has been upgraded by the addition of quadrupoles which reduce the emittance by a factor of 15. In order to do this without disturbing the beamlines, all 16 straight sections were rebuilt. Additional sextupole and octupole magnets were included, as was additional pumping capacity. Completely new beam monitor and vertical steering systems have been incorporated. The SRS was shut down on 1 October 1986 and, after recommissioning, regular scheduled operation for users at the rate of nearly 6000 h per year has been in effect again since June 1987. Scheduled operation is at 2 GeV with the 5T wiggler operational. The gain in brightness is as expected. Maximum beam current at 2 GeV is now 280 mA. Beam lifetime is 20 h at 200 mA. Diffraction patterns of small angle scattering from muscle obtained with an electronic area detector show that with the improved brilliance, diffraction lines corresponding to spacings exceeding 15 000 Å can be clearly resolved. Work is about to start on the provision of a second superconducting wiggler with 6T field feeding five new experimental stations.
Operational experience with the BESSY storage ring (invited) (abstract)
Authors: Kuske P.
Published: July 2002

The operational experience with a low emittance 800-MeV electron storage ring used as a synchrotron light source (BESSY) is presented. We will discuss problems specific to BESSY and to future high brilliance light sources like the short- and long-term stability of the beam, the lifetime of the stored electrons and the influence of an insertion device on beam dynamics.
High beam current storage at low energy for compact synchrotron radiation rings (invited)
Authors: Takada H. , Tsutsui Y. , Tomimasu T. , Sugiyama S.
Published: July 2002

A study of high beam current storage at a low energy is being conducted on the compact electron storage ring NIJI-1. In general, it is said that the stored beam lifetime is rapidly shortened as the beam energy decreases, and the high beam current storage is difficult to obtain. However, a stored beam current above a 350 mA was obtained at an injection energy of 100 MeV, and the lifetime of the stored beam is considerably long. For example, e-folding lifetime is about 2 h at 100 MeV. In this paper, we estimate the beam current decay rate due to the residual gas scattering, the ion trapping effect, and the Touschek effect, and make clear these contributions to the beam lifetime. It was clear that the Touschek lifetime is lengthened according to the bunch size growth, which is roughly explained by the longitudinal coupled bunch instability.
Fine-alignment exposure system for synchrotron x-ray lithography (invited)
Authors: Itoh Junji , Kanayama Toshihiko , Atoda Nobufumi , Hoh Koichiro
Published: July 2002

We have constructed an exposure system based on a newly developed mask-to-wafer alignment technique for use in a 1/4-μm lithography with synchrotron radiation (SR) x rays. This system consists of optics for fine alignment along the horizontal axis, vertical mask and wafer stages, a position control system, and an aluminum chamber containing them. The alignment technique uses three diffraction gratings arranged symmetrically on the mask and the wafer and detects the relative displacement directly from the phase change of the beats of diffracted light. The chamber is filled with He gas in atmospheric pressure and separated from the SR beam line in ultra high vacuum by a 25-μm-thick Be window. Using the present system, 1/2-μm-wide patterns were printed to the wafer with an alignment accuracy better than ±0.05 μm. Features and performance of the system are described.