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Dec 2005

Volume 76, Issue 12, Articles (12xxxx)

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Implementation of a modern resonant ultrasound spectroscopy system for the measurement of the elastic moduli of small solid specimens

Albert Migliori and J. D. Maynard

Rev. Sci. Instrum. 76, 121301 (2005); http://dx.doi.org/10.1063/1.2140494 (7 pages) | Cited 30 times

Online Publication Date: 29 December 2005

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The use of mechanical resonances to determine the elastic moduli of materials of interest to condensed-matter physics, engineering, materials science and more is a steadily evolving process. With the advent of massive computing capability in an ordinary personal computer, it is now possible to find all the elastic moduli of low-symmetry solids using sophisticated analysis of a set of the lowest resonances. This process, dubbed “resonant ultrasound spectroscopy” or RUS, provides the highest absolute accuracy of any routine elastic modulus measurement technique, and it does this quickly on small samples. RUS has been reviewed extensively elsewhere, but still lacking is a complete description of how to make such measurements with hardware and software easily available to the general science community. In this article, we describe how to implement realistically a useful RUS system.
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87.50.Y- Biological effects of acoustic and ultrasonic energy
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Long-term stabilization of the length of an optical reference cavity

Gaëtan Hagel, Marie Houssin, Martina Knoop, Caroline Champenois, Michel Vedel, and Fernande Vedel

Rev. Sci. Instrum. 76, 123101 (2005); http://dx.doi.org/10.1063/1.2136069 (4 pages) | Cited 3 times

Online Publication Date: 14 December 2005

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To obtain a high degree of long-term length stabilization of an optical reference cavity, its free-spectral range is locked by means of an accurate and stable frequency synthesizer. The locking scheme is twofold: a laser is locked on the Nth mode of a reference Fabry-Perot cavity and part of the laser light is shifted in frequency to be in resonance with the (N+1)th mode of the cavity. This shift is generated by an acousto-optical modulator (AOM) mounted in a double-pass scheme, matching half of the free-spectral range of the reference cavity. The resulting absolute stabilization of the length of the cavity reaches the 10−11 level per second, limited by the lock transfer properties and the frequency stability of the AOM control synthesizer.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc Modulation, tuning, and mode locking
42.79.Hp Optical processors, correlators, and modulators
42.79.Jq Acousto-optical devices

Polarization mode dispersion: Characterization of optical fiber using cross-correlation interferometry

T. B. Gibbon, A. B. Conibear, and A. W. R. Leitch

Rev. Sci. Instrum. 76, 123102 (2005); http://dx.doi.org/10.1063/1.2136880 (3 pages)

Online Publication Date: 14 December 2005

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The interferometric measurement technique is known to be a quick and reliable method for accurately measuring polarization mode dispersion (PMD) in an optical fiber. In this paper we present the means by which this technique may further be used to obtain qualitative information about the birefringent properties of the fiber under test. Polarization maintaining fiber segments are used to show that a concatenation of n birefringent segments gives rise to an interferogram with 3n interference peaks. The peak positions are further related to the total birefringent contribution of each of the fiber segments. These findings are then used to interpret measurement results and comment on the PMD and related birefringent properties of numerous single mode fibers. Stress is shown to introduce PMD in uncabled single mode fiber. Interferometric measurements are also used to determine the number of birefringent segments in both undeployed and deployed cabled fibers. Polarization optical time domain reflectometry is used successfully to verify these results.
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42.81.Cn Fiber testing and measurement of fiber parameters
42.81.Gs Birefringence, polarization
42.81.Dp Propagation, scattering, and losses; solitons
07.60.Ly Interferometers
07.60.Hv Refractometers and reflectometers

Slice imaging of photodissociation of spatially oriented molecules

M. Laura Lipciuc, Alrik J. van den Brom, Laura Dinu, and Maurice H. M. Janssen

Rev. Sci. Instrum. 76, 123103 (2005); http://dx.doi.org/10.1063/1.2138691 (7 pages) | Cited 8 times

Online Publication Date: 14 December 2005

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An electrostatic ion lens to spatially orient parent molecules and to image the angular distribution of photofragments is presented. Photodissociation of laboratory-oriented molecules makes it possible to study the dynamics of the dissociation process in more detail compared to photodissociation of nonoriented molecules. Using the velocity map imaging technique in combination with the slice imaging technique, the spatial recoil distribution of the photofragments can be measured with high resolution and without symmetry restrictions. Insertion of orientation electrodes between the repeller and the extractor of a velocity mapping electrostatic lens severely distorts the ion trajectories. The position where the ions are focused by the lens, the focal length, can be very different in the directions parallel and perpendicular to the inserted orientation electrodes. The focal length depends on the exact dimensions and positions of the electrodes of the ion lens. As this dependence is different in both directions, this dependence can be used to correct for the distorted ion trajectories. We discuss the design of an electrostatic ion lens, which is able to orient parent molecules and map the velocity of the photofragments. We report sliced images of photofragments from photolysis of spatially oriented CD3I molecules to demonstrate the experimental combination of molecular orientation and velocity map slice imaging with good resolution.
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41.85.Ne Electrostatic lenses, septa
33.80.Gj Diffuse spectra; predissociation, photodissociation
82.50.-m Photochemistry
37.20.+j Atomic and molecular beam sources and techniques

A microbeam wavelength-dispersive x-ray fluorescence system and its application for thin-film analysis

Ning Gao, Zewu Chen, and Qifan Xiao

Rev. Sci. Instrum. 76, 123104 (2005); http://dx.doi.org/10.1063/1.2140448 (5 pages) | Cited 3 times

Online Publication Date: 14 December 2005

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A low-power wavelength dispersive x-ray fluorescence (WDXRF) system with a spatial resolution of 25 μm has been built to measure thin-film thickness. By using advanced x-ray optics and a 50-W air-cooled x-ray tube, the system achieved a detection limit equivalent to that of a conventional WDXRF system that employs a 4-kW x-ray tube and a spatial resolution of 10 mm in diameter. For a 25-nm-thick tantalum underlayer, a detection limit of 0.18 nm was achieved and measurement precision of 2% was obtained with a measurement time of 100 s.
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07.85.-m X- and γ-ray instruments
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Compact high-resolution spectral phase shaper

S. Postma, P. van der Walle, H. L. Offerhaus, and N. F. van Hulst

Rev. Sci. Instrum. 76, 123105 (2005); http://dx.doi.org/10.1063/1.2140465 (4 pages) | Cited 10 times

Online Publication Date: 14 December 2005

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The design and operation of a high-resolution spectral phase shaper with a footprint of only 7×10 cm2 is presented. The liquid-crystal modulator has 4096 elements. More than 600 independent degrees of freedom can be positioned with a relative accuracy of 1 pixel. The spectral shaping of pulses from a broadband Ti:sapphire laser is verified by a hybrid cross-frequency-resolved optical gating/Grenouille measurement and intensity autocorrelation. We demonstrate the ability to split one pulse into two or more pulses with a programmable delay of more than 8.5 ps. To our knowledge this represents the most compact high resolution device in liquid-crystal modulator-based shaping to this date.
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41.85.Ct Particle beam shaping, beam splitting
42.60.Fc Modulation, tuning, and mode locking
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Hp Optical processors, correlators, and modulators

Focused-laser interferometric position sensor

Stephen J. Friedman, Brett Barwick, and Herman Batelaan

Rev. Sci. Instrum. 76, 123106 (2005); http://dx.doi.org/10.1063/1.2130667 (5 pages) | Cited 5 times

Online Publication Date: 21 December 2005

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We describe a simple method to measure the position shifts of an object with a range of tens of micrometers using a focused-laser (FL) interferometric position sensor. In this article we examine the effects of mechanical vibration on FL and Michelson interferometers. We tested both interferometers using vibration amplitudes ranging from 0 to 20 μm. Our FL interferometer has a resolution much better than the diffraction grating periodicities of 10 and 14 μm used in our experiments. A FL interferometer provides improved mechanical stability at the expense of spatial resolution. Our experimental results show that Michelson interferometers cannot be used when the vibration amplitude is more than an optical wavelength. The main purpose of this article is to demonstrate that a focused-laser interferometric position sensor can be used to measure the position shifts of an object on a less sensitive, micrometer scale when the vibration amplitude is too large to use a Michelson interferometer.
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42.79.Pw Imaging detectors and sensors
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
07.60.Ly Interferometers
42.79.Qx Range finders, remote sensing devices; laser Doppler velocimeters, SAR, and LIDAR

Diffraction efficiency and diffraction bandwidth of thermal-gradient and composition-gradient crystals

R. Smither, K. Abu Saleem, M. Beno, C. Kurtz, A. Khounsary, and N. Abrosimov

Rev. Sci. Instrum. 76, 123107 (2005); http://dx.doi.org/10.1063/1.2130928 (19 pages) | Cited 2 times

Online Publication Date: 21 December 2005

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Measurements were made at the Advanced Photon Source at Argonne National Laboratory on the diffraction efficiency and diffraction bandwidth of a thermal-gradient crystal (Si) and a composition-gradient crystal (Si-Ge) to which a thermal gradient was applied. Gradient crystals are crystals in which the spacing between crystalline planes varies with the position in the crystal. This change in the crystal plane spacing is obtained by applying a thermal gradient to a single crystal or by growing a two-component crystal in which the ratio of the two components changes with position in the crystal. Measurements were made at two energies, 92.6 and 153 keV. Both crystals were 1-cm cubes. Laue diffraction (transmission diffraction) was used in all experiments. The thermal gradient was applied perpendicular to the [111] diffraction planes of the pure silicon crystal and perpendicular the [400] diffraction planes in the composition-gradient crystal (Si-Ge). The thermal gradient applied to the crystals was quite uniform. This resulted in nearly spherical surfaces for the crystalline planes. Changing the value of the thermal gradient applied to the crystals changed the radius of curvature of the spherical surface. The thermal gradients were varied between 0.0 and 114 °C/cm, resulting in radii of curvature from near infinity down to 40 m. By adjusting the thermal gradient applied to the crystals, one obtained diffraction efficiencies between 0.90 and 0.95 and bandwidths of up to 100 arc sec. The diffraction efficiency in the Laue geometry is defined as the ratio of the intensity of the diffracted beam to the intensity of the undiffracted beam that passes through the crystal when there is no diffraction. The length of the crystal traversed by the x-ray beam was 1.0 cm in all cases.
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61.05.cp X-ray diffraction

Fast and compact multichannel photon coincidence unit for quantum information processing

Sascha Gaertner, Harald Weinfurter, and Christian Kurtsiefer

Rev. Sci. Instrum. 76, 123108 (2005); http://dx.doi.org/10.1063/1.2149007 (6 pages)

Online Publication Date: 21 December 2005

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We present a fast and compact multichannel coincidence unit to count all possible single and coincidence detection events in an experiment with eight single-photon detectors at once. Using high-speed electronics and a microcontroller, this device is able to process up to 800 000 events/s. The coincidence window can be tuned within a range of 4–12 ns. The device can be easily scaled to any number of input channels and is thus ideally suited for efficient multiphoton quantum information processing.
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42.50.-p Quantum optics
42.30.-d Imaging and optical processing
03.67.Hk Quantum communication
03.67.Lx Quantum computation architectures and implementations

GaP THz wave generator and THz spectrometer using Cr:Forsterite lasers

Ken Suto, Tetsuo Sasaki, Tadao Tanabe, Kyosuke Saito, Jun-ichi Nishizawa, and Masahiko Ito

Rev. Sci. Instrum. 76, 123109 (2005); http://dx.doi.org/10.1063/1.2140223 (3 pages) | Cited 14 times

Online Publication Date: 27 December 2005

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We have developed a type of THz wave generator that uses Cr:Forsterite lasers as the pump and signal sources for difference frequency generation in GaP (Cr:F source system). We confirmed the generation of THz waves in the frequency range from 0.3 to 7.5 THz, which is just similar to that obtained using the THz wave generator previously developed utilizing yttrium aluminum garnet and optical parametric oscillator (OPO) lasers (OPO source system). A peak output power of 100 mW was obtained from 1.2 to 5 THz when the power of the two input beams was 3 mJ each, similar to the OPO source system. A wide measurable frequency range from below 0.6 THz to over 6 THz was obtained by using the Cr:F source system as the light source of a spectrometer, which has the merits of simple structure, easy maintenance, and low cost compared with the OPO source system. Although the linewidth of the Cr:F source system is greater than that of the OPO source system, the THz spectrometer still has sufficient resolution for measuring solids or liquids at room temperature.
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07.57.−c
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
63.20.D- Phonon states and bands, normal modes, and phonon dispersion
87.64.−t

High-temperature calcium vapor cell for spectroscopy on the 4s2 math–4s4p math intercombination line

Christopher J. Erickson, Brian Neyenhuis, and Dallin S. Durfee

Rev. Sci. Instrum. 76, 123110 (2005); http://dx.doi.org/10.1063/1.2148992 (5 pages) | Cited 2 times

Online Publication Date: 27 December 2005

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We have demonstrated a high-temperature vapor cell for absorption spectroscopy on the Ca intercombination line. The cell uses a dual-chamber design to achieve the high temperatures necessary for an optically dense vapor while avoiding the necessity of high-temperature vacuum valves and glass-to-metal seals. We have observed over 50% absorption in a single pass through the cell. Although pressure broadening in the cell prevented us from performing saturated-absorption spectroscopy, the broadening resulted in higher signal-to-noise ratios by allowing us to probe the atoms with intensities much greater than the 0.2 μW/cm2 saturation intensity of the unbroadened transition. The techniques presented in this article could easily be applied to study other transitions in a variety of atomic species.
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07.60.Rd Visible and ultraviolet spectrometers
42.65.-k Nonlinear optics

Anomalous attenuation at low temperatures in high-intensity helium beam sources

H. Hedgeland, A. P. Jardine, W. Allison, and J. Ellis

Rev. Sci. Instrum. 76, 123111 (2005); http://dx.doi.org/10.1063/1.2149008 (5 pages) | Cited 2 times

Online Publication Date: 27 December 2005

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High-intensity supersonic helium beam sources are a critical component in modern thermal energy helium atom scattering apparatuses. In common with sources developed elsewhere, we have observed beam attenuation at low temperature as the helium flow through the nozzle is increased. A detailed analysis of the measurements demonstrates that direct backscattering in the nozzle-skimmer region is likely to be the major attenuation source. A numerical model, which describes the principle sources of scattering in the region between source and skimmer, is shown to provide a good description of the experimental data for a range of flow conditions and for stagnation temperatures between 37 and 300 K. The model includes partial accommodation of atoms scattered from surfaces of the skimmer and chamber, together with a realistic scattering potential. We use the model to predict the effect of various geometric alterations, aimed at improving the ultimate beam intensity.
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37.20.+j Atomic and molecular beam sources and techniques
34.35.+a Interactions of atoms and molecules with surfaces

Evaluation of the sensitivity to mechanical vibrations of an IR Fourier spectrometer

L. Comolli and B. Saggin

Rev. Sci. Instrum. 76, 123112 (2005); http://dx.doi.org/10.1063/1.2149009 (8 pages) | Cited 7 times

Online Publication Date: 27 December 2005

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This article presents an experimental and theoretical investigation of the sensitivity to mechanical disturbances of a Fourier-transform infrared spectrometer, the Planetary Fourier Spectrometer, currently orbiting around Mars onboard ESA Mars Express orbiter. A theoretical analysis has been performed in order to highlight the expected effects of the vibrations, then laboratory tests have been designed and carried out for instrument characterization. The two classical types of disturbance effects were expected in the case of mechanical vibrations: the interfering type, leading to an additive contribution to the interferograms, and the modifying type, which changes the interferometer sensitivity. Both effects have been evidenced in the experimental tests and the instrument sensitivity derived; moreover, the effects on the spectra, which are the Fourier transform of interferograms, are highlighted and characterized. The effects of both harmonic and random broadband spectrum disturbances have been considered. While the broadband disturbances increase uniformly the noise, harmonic disturbances produce localized effects in the spectra and replicas of the spectral features with wave-number shifts proportional to disturbance frequency. It has also been highlighted that, the disturbances from mechanical vibrations being uncorrelated with the interferometric signals, by spectrum averaging, like all the other noise sources, they can be reduced. Methods for spectrum diagnostics and for increasing the signal-to-noise ratio in vibration-affected spectra are proposed as well.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
95.55.Qf Photometric, polarimetric, and spectroscopic instrumentation
95.55.Br Astrometric and interferometric instruments
07.60.Ly Interferometers
42.30.Kq Fourier optics
42.87.-d Optical testing techniques
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Compact 300 keV electron gun for radiation processing

L. Auditore, R. C. Barnà, D. De Pasquale, S. Interdonato, A. Italiano, A. Trifiró, and M. Trimarchi

Rev. Sci. Instrum. 76, 123301 (2005); http://dx.doi.org/10.1063/1.2140466 (4 pages)

Online Publication Date: 14 December 2005

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A new self-shielded system for surface radiation treatments has been developed, based on a 300 keV electron gun, able to irradiate a 100 mm×10 mm area. The compact and durable system described in this paper provides the required dose of treatment for several industrial or scientific research applications, with a good reproducibility of the parameters.
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29.25.Bx Electron sources
87.53.-j Effects of ionizing radiation on biological systems
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An upgraded 32-channel heterodyne electron cyclotron emission radiometer on Tore Supra

J. L. Ségui, D. Molina, G. Giruzzi, M. Goniche, G. Huysmans, P. Maget, and M. Ottaviani

Rev. Sci. Instrum. 76, 123501 (2005); http://dx.doi.org/10.1063/1.2140225 (6 pages) | Cited 13 times

Online Publication Date: 14 December 2005

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A 32-channel, 1 GHz spaced heterodyne radiometer is used on the Tore Supra tokamak to measure electron cyclotron emission (ECE) in the frequency range 78–110 GHz for the ordinary mode (O:E‖B,k⊥B) and 94–126 GHz for the extraordinary mode (X:E⊥B,k⊥B). The radial resolution is essentially limited by ECE relativistic effects, depending on electron temperature and density, and not by the channels’ frequency spacing. The time resolution depends on the acquisition scheme: the system allows for both 1 ms and 10 μs acquisition. For example, this leads to precise electron temperature mapping during MHD activity. First experimental results obtained with this upgraded 32-channel radiometer are presented.
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52.70.Gw Radio-frequency and microwave measurements
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
52.55.Fa Tokamaks, spherical tokamaks
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.27.Ny Relativistic plasmas
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
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A multiaxis stage configured for rapid observations of plane samples at multiple angles

Michael Lamvik and Sonia Grego

Rev. Sci. Instrum. 76, 123701 (2005); http://dx.doi.org/10.1063/1.2140444 (3 pages)

Online Publication Date: 14 December 2005

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We describe a mechanical configuration that allows any point on a flat sample to be moved to any angle of tilt and rotation (within the limits of which the stage is capable) while maintaining the area of interest at a constant focus and within the field of view of a fixed optical system. We describe eight axes of movement required to obtain the desired stability of focus and view area. We demonstrate the proposed concept by assembling an instrument using mostly existing parts. This optical-microscope-based instrument allows sample tilts to 60° and unlimited rotation while maintaining the point of interest within better than 17 μm in x, y, and z of the center of the field of view of a 100× optical system.
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07.60.Pb Conventional optical microscopes
42.15.Eq Optical system design

A multiphoton laser scanning microscope setup for transcranial in vivo brain imaging on mice

Gabriele Nase, P. Johannes Helm, Trond Reppen, and Ole Petter Ottersen

Rev. Sci. Instrum. 76, 123702 (2005); http://dx.doi.org/10.1063/1.2140487 (5 pages) | Cited 7 times

Online Publication Date: 14 December 2005

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We describe a multiphoton laser scanning microscope setup for transcranial in vivo brain imaging in mice. The modular system is based on a modified industrial standard Confocal Scanning Laser Microscope (CSLM) and is assembled mainly from commercially available components. A special multifunctional stage, which is optimized for both laser scanning microscopic observation and preparative animal surgery, has been developed and built. The detection unit includes a highly efficient photomultiplier tube installed in a Peltier-cooled thermal box shielding the detector from changes in room temperature and from distortions caused by external electromagnetic fields. The images are recorded using a 12-bit analog–to–digital converter. Depending on the characteristics of the staining, individual nerve cells can be imaged down to at least 100 μm below the intact cranium and down to at least 200 μm below the opened cranium.
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87.63.L- Visual imaging
42.62.Be Biological and medical applications
07.60.Pb Conventional optical microscopes
87.19.L- Neuroscience

Electron-beam tip/sample heating device for a scanning tunneling microscopy

H. F. Ding, J. E. Pearson, Dongqi Li, Ruihua Cheng, F. Y. Fradin, and S. D. Bader

Rev. Sci. Instrum. 76, 123703 (2005); http://dx.doi.org/10.1063/1.2140339 (4 pages) | Cited 9 times

Online Publication Date: 21 December 2005

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We present an electron-beam heating device for a scanning tunneling microscopy (STM) that can be used for heating both the STM tip and the sample to 2200 K. Mounted on a linear bellows with electrical feedthroughs, the device can be readily installed into the transfer path of a vacuum load lock. We demonstrate the heating capability of the device by flash cleaning Ru(0001) and Fe(001) crystals, and W tips. The flash-cleaned W tips are coated with Fe and further used for spin-polarized imaging of the Mn/Fe(001) system.
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07.79.Cz Scanning tunneling microscopes

An atomic force microscope tip as a light source

Valentin Lulevich, Chris Honig, and William A. Ducker

Rev. Sci. Instrum. 76, 123704 (2005); http://dx.doi.org/10.1063/1.2149149 (5 pages) | Cited 3 times

Online Publication Date: 21 December 2005

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We present a simple method for causing the end of a silicon nitride atomic force microscope (AFM) tip to emit light, and we use this emitted light to perform scanning near-field optical microscopy. Illumination of a silicon nitride AFM tip by blue (488 nm) or green (532 nm) laser light causes the sharp part of the tip to emit orange light. Orange light is emitted when the tip is immersed in either air or water; and while under illumination, emission continues for a period of many hours without photobleaching. By careful alignment of the incident beam, we can arrange the scattered light to decay as a function of the tip-substrate separation with a decay length of 100–200 nm. The exponential decay of the intensity means that the emitted light is dominated by contributions from parts of the tip that are near the sample, and therefore the emitted orange light can be used to capture high-resolution near-field optical images in air or water.
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07.79.Lh Atomic force microscopes
42.72.-g Optical sources and standards
78.55.Hx Other solid inorganic materials
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Eucentric four-axis ultrahigh vacuum goniometer for reflection high-energy electron diffraction applications

A. Schmehl, R. R. Schulz, and J. Mannhart

Rev. Sci. Instrum. 76, 123901 (2005); http://dx.doi.org/10.1063/1.2138687 (4 pages)

Online Publication Date: 14 December 2005

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The design and performance of a four-axis low-profile eucentric UHV goniometer for in situ reflection high-energy electron diffraction (RHEED) studies during film deposition is reported. The design provides one translational and three rotational degrees of freedom that are fully independent. Although developed to facilitate high-pressure RHEED during the growth of oxide thin films by pulsed laser deposition, this goniometer design is applicable to other UHV techniques including molecular beam epitaxy. The goniometer requires only a single DN 100 CF flange (6 in. o.d., 100 mm i.d.), making it suitable for small deposition systems, too. Samples, attached to a resistively heated holder, can be easily transferred on and off of the goniometer without breaking vacuum. The holder accommodates samples up to 10 mm×10 mm in size and allows them to be heated to 900 °C in pure oxygen while being attached to the goniometer. Full eucentric motion of the hot sample is possible with a typical axis precision of <0.1°. Most of the mechanism is located in air, allowing the use of standard materials and lubricants, substantially reducing the in-vacuum mechanics, and increasing the precision, reliability, and robustness of the system.
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07.85.-m X- and γ-ray instruments
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
81.15.Fg Pulsed laser ablation deposition
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Composite bimetallic gasket and compact mechanical anvil retainer for magnetic measurements in a diamond-anvil cell to 30 GPa

Mamoru Ishizuka

Rev. Sci. Instrum. 76, 123902 (2005); http://dx.doi.org/10.1063/1.2140447 (4 pages) | Cited 2 times

Online Publication Date: 14 December 2005

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A composite gasket was designed for diamond-anvil cells where the load was supported mainly by the inner part made of NiCrAl with a diameter slightly larger than the culet of the anvil. A BeCu girdle encased the NiCrAl washer and prevented it from fracturing. The thickness of the gasket was about 30 μm at a pressure of 30 GPa applied with a pair of diamond anvils having 500 and 550 μm culets. The magnetic contribution of the composite gasket to the background signal was almost the same as that of a BeCu gasket having the same size. The diamond anvils were fixed to the pistons with four miniature screws through small BeCu rings that were press fitted to the circumference of the diamond anvils. The performance of this composite gasket together with the anvil retainer was illustrated by the measurements of the temperature dependence of the dc magnetic susceptibility of Cs2CuF4 under various pressures up to 26 GPa using a superconducting quantum interference device vibrating coil magnetometer.
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07.55.-w Magnetic instruments and components
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
75.30.Cr Saturation moments and magnetic susceptibilities

Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts

Z. Zhao, T. Diemant, T. Häring, H. Rauscher, and R. J. Behm

Rev. Sci. Instrum. 76, 123903 (2005); http://dx.doi.org/10.1063/1.2140449 (8 pages) | Cited 3 times

Online Publication Date: 14 December 2005

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We describe the design and performance of a high-pressure reaction cell for simultaneous kinetic and in situ infrared reflection (IR) spectroscopic measurements on model catalysts at elevated pressures, between 10−3 and 103 mbars, which can be operated both as batch reactor and as flow reactor with defined gas flow. The cell is attached to an ultrahigh-vacuum (UHV) system, which is used for sample preparation and also contains facilities for sample characterization. Specific for this design is the combination of a small cell volume, which allows kinetic measurements with high sensitivity under batch or continuous flow conditions, the complete isolation of the cell from the UHV part during UHV measurements, continuous temperature control during both UHV and high-pressure operation, and rapid transfer between UHV and high-pressure stage. Gas dosing is performed by a designed gas-handling system, which allows operation as flow reactor with calibrated gas flows at adjustable pressures. To study the kinetics of reactions on the model catalysts, a quadrupole mass spectrometer is connected to the high-pressure cell. IR measurements are possible in situ by polarization-modulation infrared reflection-absorption spectroscopy, which also allows measurements at elevated pressures. The performance of the setup is demonstrated by test measurements on the kinetics for CO oxidation and the CO adsorption on a Au/TiO2/Ru(0001) model catalyst film at 1–50 mbar total pressure.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
07.75.+h Mass spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques

Production and characterization of micron-sized filaments of solid argon

Michael Grams, Boleslaw Stasicki, and J. Peter Toennies

Rev. Sci. Instrum. 76, 123904 (2005); http://dx.doi.org/10.1063/1.2135277 (9 pages) | Cited 1 time

Online Publication Date: 21 December 2005

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A continuous 50-μm-diam filament of solid argon is produced in a moderate vacuum (4.2×10−3 mbar) by cooling argon gas to 70–90 K over the last 8 mm of a long fused silica capillary. Prior to formation of the straight filament the jet shows different stages characterized by spraying, snowballing, or spiraling filaments as documented by charge-coupled device (CCD) camera microscope pictures. Consecutive CCD pictures are used to measure the filament velocities, which increase with the driving gas pressure P0 up to about 4.0 cm/s at P0 = 400 bars with an intermediate peak at about 80 bars. This technique may find applications for producing wall-less cryogenic matrices, targets for laser plasma sources of extreme UV and soft-x-ray sources, plasma implosion experiments, or H2 pellets for injection into fusion reactors.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
47.27.wg Turbulent jets

X-ray-absorption fine structure measurement with parallel-plate capacitor: Observation of surface electronic states of metals

Masashi Ishii and Aiko Nakao

Rev. Sci. Instrum. 76, 123905 (2005); http://dx.doi.org/10.1063/1.2148998 (7 pages) | Cited 1 time

Online Publication Date: 27 December 2005

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For surface electronic state analyses of metals, we developed a new x-ray-absorption fine structure (XAFS) measurement technique with a parallel-plate capacitor. Since the capacitance is changed by x-ray-induced photoionization on the metal surface, the surface XAFS spectrum of a metal can be obtained from the capacitance dependent on the x-ray photon energy. We adopted this technique to the Cu metals. The XAFS spectrum at the Cu K absorption edge is different from the conventional XAFS spectrum of either Cu or Cu2O. This finding suggests that the XAFS spectrum indicates two-dimensional (2D) electronic states between the Cu bulk and the Cu2O native oxide layer. The 2D electronic states were characterized by degeneration of Cu 4pπ and a blueshift of Cu 4pσ. These characteristics can be explained by hybridization of vertical Cu 4pz with horizontal 4px and 4py in CuO-like structure at the interface.
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07.85.Nc X-ray and γ-ray spectrometers
78.70.Dm X-ray absorption spectra
73.20.At Surface states, band structure, electron density of states

A double-beam common path laser interferometer for the measurement of electric field-induced strains of piezoelectric thin films

Z. Huang and R. W. Whatmore

Rev. Sci. Instrum. 76, 123906 (2005); http://dx.doi.org/10.1063/1.2149002 (4 pages) | Cited 1 time

Online Publication Date: 27 December 2005

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We report in this paper the development of a modified Mach-Zehnder-type double-beam common path laser interferometer for the measurement of electric field-induced strain in piezoelectric materials, especially for the thin films. Compared to previous interferometers, this one is simpler and more compact, and the measurement and reference arms share a common path for most of the optical length. Example results have been reported for the quartz, lead zirconate titanate (PZT) ceramic sample, and PZT thin films. Double- and single-beam measurements have been carried out at different frequencies for the same spot of a PZT thin-film sample and it was found that the single-beam values were a few times of the values as obtained from the double-beam technique. This phenomenon is confirmed by the laser scanning vibrometer measurements.
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07.60.Ly Interferometers
07.10.Pz Instruments for strain, force, and torque
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.65.Ly Strain-induced piezoelectric fields
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