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Aug 2004

Volume 75, Issue 8, pp. 2499-2777

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Instrumentation for trace detection of high explosives

D. S. Moore

Rev. Sci. Instrum. 75, 2499 (2004); http://dx.doi.org/10.1063/1.1771493 (14 pages) | Cited 113 times

Online Publication Date: 26 July 2004

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There is at present an urgent need for trace detection of high explosives, with applications to screening of people, packages, luggage, and vehicles. A great concern, because of recent terrorist activities, is for the development of methods that might allow detection and identification of explosives at a stand off distance. Nearly every analytical chemical method has been or is being applied to this problem. This review outlines the properties of explosives that might be utilized in detection schemes, discusses sampling issues, presents recent method developments with particular attention to detection limits, speed of analysis, and portability, and looks towards future developments.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
82.80.Bg Chromatography
78.30.-j Infrared and Raman spectra
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.75.+h Mass spectrometers
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back to top NUCLEAR PHYSICS, FUSION AND PLASMAS

Array of HgI2 detectors on the HL-1M Tokamak

Yang Jinwei, Zhang Wei, and Wang Shiqing

Rev. Sci. Instrum. 75, 2513 (2004); http://dx.doi.org/10.1063/1.1771484 (4 pages) | Cited 1 time

Online Publication Date: 26 July 2004

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An array of seven HgI2 detectors, which are suitable for detecting the time and space evolution of the x-ray radiation flux and energy spectrum in the range between 15–150 keV relevant to suprathermal electron and runaway electrons was installed on the HL-1M Tokamak (R0 = 1.02 m, a = 0.26 m, BT = 3.5 T, IP = 350 kA, ne = 3–6×1013 cm−3, Te = 0.8–1.5 keV). Our iodine mercury (HgI2) semiconductor detectors possess the properties of low noise level, high detection efficiency, high counting rate, high energy resolution, and working at room temperature. Every detector is a high quality, high purity detector cut out of a big size HgI2 crystal. A new type of multichannel energy spectrometer with a high speed acquisition system was developed. Therefore, the spatial and temporal distribution of the x-ray energy spectrum induced by thermal and superthermal electrons can be observed.
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52.55.Fa Tokamaks, spherical tokamaks
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
52.70.La X-ray and γ-ray measurements
52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
29.40.Wk Solid-state detectors
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Time-resolved measurements with a mercury resonance ionization imaging detector

M. R. Shepard, J. P. Temirov, O. I. Matveev, N. V. Chigarev, B. W. Smith, and J. D. Winefordner

Rev. Sci. Instrum. 75, 2517 (2004); http://dx.doi.org/10.1063/1.1771485 (7 pages)

Online Publication Date: 26 July 2004

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The recently developed mercury resonance ionization imaging detector (RIID) has many potential applications in the field of imaging science. We have demonstrated that useful information can be obtained from the time-resolved ionization signal detected along with the image of the object. Clearly distinguishable time-resolved signals from resonance ionization of mercury atoms and photoelectrons created within the channels of a microchannel plate by a UV signal transition of Hg at 253.7 nm were observed. Also, a new source of noise has been identified as low-mass ion desorption by 253.7 nm radiation from the inner parts of the Hg RIID. The time-resolved signal detection allowed temporal correction for the additional noises caused by nonresonant ionization processes inside the RIID, such as photoelectric effect and low-mass ion desorption. The temporal resolution of the RIID could be used for frequency shifted radiation detection and imaging.
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42.79.Pw Imaging detectors and sensors
72.40.+w Photoconduction and photovoltaic effects
79.60.Bm Clean metal, semiconductor, and insulator surfaces
68.43.Mn Adsorption kinetics
back to top MICROSCOPY AND IMAGING

Top-down topography of deeply etched silicon in the scanning electron microscope

Oliver C. Wells, Conal E. Murray, Jonathan L. Rullan, and Lynne M. Gignac

Rev. Sci. Instrum. 75, 2524 (2004); http://dx.doi.org/10.1063/1.1771491 (5 pages) | Cited 2 times

Online Publication Date: 26 July 2004

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It is proposed to measure the cross sections of steep-sided etched lines and similar deep surface topography on partially completed silicon integrated circuit wafers using either the backscattered electron (BSE) or the low-loss electron (LLE) image in the scanning electron microscope (SEM). These images contain regions where the collected signal is zero because there is no direct line of sight between the landing point of the electron beam on the specimen and the BSE or LLE detector. It is proposed to use the boundary of such a region in the SEM image as a geometrical line to measure the surface topography. Or alternatively, a shadow can be seen in the distribution of either BSE or LLE with an image-forming detector system. The use of this shadow position on the detector to measure deep surface topography will be demonstrated.
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68.47.Fg Semiconductor surfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.65.Cf Surface cleaning, etching, patterning
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
back to top CONDENSED MATTER; MATERIALS

Depth sensing and dissipation in tapping mode atomic force microscopy

Hugues Bodiguel, Hélène Montes, and Christian Fretigny

Rev. Sci. Instrum. 75, 2529 (2004); http://dx.doi.org/10.1063/1.1771495 (7 pages) | Cited 13 times

Online Publication Date: 26 July 2004

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Tapping mode atomic force microscopy is frequently used to image the surface of soft materials; it is also a powerful technique for nanomechanical analysis of surfaces. We report here an investigation of the depth sensing of the method on soft polymers. The chosen approach is based on the analysis of phase images of a model filled elastomer material. It leads to the determination of the depths of the hard particles lying under the surface. We found that tapping mode can probe interfaces buried under up to 80 nm of polymer. Under given tapping conditions, the penetration depth of the tip into the polymer is observed to depend on the layer thickness. However we show that, for a given penetration depth, the dissipated energy is independent of the thickness of the polymer layer under the tip. This suggests that the phase signal does not originate in the bulk viscoelasticity of the elastomer. Our observations support the hypothesis that, in tapping mode experiments on elastomers, the phase signal has an adhesive origin. Then, on surfaces with uniform interfacial properties, the phase images may reflect the local elastic properties of the sample, since they modify the tip-surface adhesive interactions.
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07.79.Lh Atomic force microscopes
68.37.Ps Atomic force microscopy (AFM)
68.35.Md Surface thermodynamics, surface energies
05.70.Np Interface and surface thermodynamics

Ultra-stable oven designed for x-ray reflectometry and ellipsometry studies of liquid surfaces

Matt Brown, Serif Uran, Bruce Law, Lyle Marschand, Larry Lurio, I. Kuzmenko, and T. Gog

Rev. Sci. Instrum. 75, 2536 (2004); http://dx.doi.org/10.1063/1.1771496 (5 pages) | Cited 4 times

Online Publication Date: 26 July 2004

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Stable temperature control is highly desirable for reflectivity studies of binary liquid mixtures. In this article we report on the construction of an oven that possesses good temperature stability ( ∼ 1 mK/day) and small transverse temperature gradients (<1 mK/cm). The oven has a horizontal geometry and can be used for either x-ray reflectometry or ellipsometry measurements from the liquid∕vapor surfaces of such systems. Details of the oven design together with test results are provided.
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07.60.Hv Refractometers and reflectometers
07.60.Fs Polarimeters and ellipsometers
07.20.Hy Furnaces; heaters
68.03.-g Gas-liquid and vacuum-liquid interfaces
back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Low-noise computer-controlled current source for quantum coherence experiments

S. Linzen, T. L. Robertson, T. Hime, B. L. T. Plourde, P. A. Reichardt, and John Clarke

Rev. Sci. Instrum. 75, 2541 (2004); http://dx.doi.org/10.1063/1.1771499 (4 pages) | Cited 2 times

Online Publication Date: 26 July 2004

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We describe a dual current source designed to provide static flux biases for a superconducting qubit and for the Superconducting QUantum Interference Device (SQUID) which measures the qubit state. The source combines digitally programmable potentiometers with a stabilized voltage source. Each channel has a maximum output of ±1 mA, and can be adjusted with an accuracy of about ±1 nA. Both current supplies are fully computer controlled and designed not to inject digital noise into the quantum bit and SQUID during manipulation and measurement of the flux. For a 275 μA setting, the measured noise current is 2.6 parts per million (ppm) rms, in a bandwidth of 0.0017–10 Hz, from which we estimate dephasing times of hundreds of nanoseconds in the particular case of our own qubit design. By resetting the current every 10 min, we are able to reduce the drift to no more than 5 ppm at a current of 750 μA over a period of 3 days. The current source has been implemented without thermal regulation inside a radiofrequency-shielding room, and is used routinely in our quantum coherence experiments.
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85.25.Dq Superconducting quantum interference devices (SQUIDs)
84.30.Jc Power electronics; power supply circuits
back to top CONDENSED MATTER; MATERIALS

Sensitivity improvement in surface infrared spectroscopy: Design, characteristics, and application of a high-temperature graphite source

Eldad Herceg, Hugo Celio, and Michael Trenary

Rev. Sci. Instrum. 75, 2545 (2004); http://dx.doi.org/10.1063/1.1771500 (6 pages) | Cited 5 times

Online Publication Date: 26 July 2004

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An infrared source designed to increase the sensitivity of the technique of reflection absorption infrared spectroscopy (RAIRS) for the detection of molecular adsorbates at submonolayer coverages on metal surfaces is described. The source is based on a graphite element with a lifetime of 500 h when operated at a temperature of ∼ 2300 K in a static pressure of 800 Torr of argon. The design allows for rapid and easy replacement of the low cost graphite element. The signal-to-noise ratio (SNR) achieved with this source for spectra obtained with both mercury cadmium telluride and indium antimonide detectors is a factor of 3-higher than obtained with a standard silicon carbide (SiC) source operated at ∼ 1500 K. With the higher SNR available with the graphite source it was possible to detect two vibrational features, δs(CH3) of methyl at 1247 cm–1, and ν(CH) of methylidyne at 2956 cm–1, that were not detected in previous RAIRS studies.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
68.43.Mn Adsorption kinetics
78.30.Hv Other nonmetallic inorganics

Performance summary on a high power dense plasma focus x-ray lithography point source producing 70 nm line features in AlGaAs microcircuits

Rodney Petr, Alexander Bykanov, Jay Freshman, Dennis Reilly, Joseph Mangano, Maureen Roche, Jason Dickenson, Mitchell Burte, and John Heaton

Rev. Sci. Instrum. 75, 2551 (2004); http://dx.doi.org/10.1063/1.1771502 (9 pages) | Cited 15 times

Online Publication Date: 26 July 2004

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A high average power dense plasma focus (DPF), x-ray point source has been used to produce ∼ 70 nm line features in AlGaAs-based monolithic millimeter-wave integrated circuits (MMICs). The DPF source has produced up to 12 J per pulse of x-ray energy into 4π steradians at ∼ 1 keV effective wavelength in ∼ 2 Torr neon at pulse repetition rates up to 60 Hz, with an effective x-ray yield efficiency of ∼ 0.8%. Plasma temperature and electron concentration are estimated from the x-ray spectrum to be ∼ 170 eV and ∼ 5⋅1019 cm−3, respectively. The x-ray point source utilizes solid-state pulse power technology to extend the operating lifetime of electrodes and insulators in the DPF discharge. By eliminating current reversals in the DPF head, an anode electrode has demonstrated a lifetime of more than 5 million shots. The x-ray point source has also been operated continuously for 8 h run times at 27 Hz average pulse recurrent frequency. Measurements of shock waves produced by the plasma discharge indicate that overpressure pulses must be attenuated before a collimator can be integrated with the DPF point source.
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84.40.Lj Microwave integrated electronics
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
52.59.Px Hard X-ray sources
52.59.Hq Dense plasma focus
back to top THERMOMETRY; THERMAL DIFFUSIVITY; ACOUSTIC; PHOTOTHERMAL AND PHOTOACOUSTIC

Photoacoustic determination of the plasmon enhanced electric field at a corrugated metal interface

R. J. Matelon, D. M. Newman, and M. L. Wears

Rev. Sci. Instrum. 75, 2560 (2004); http://dx.doi.org/10.1063/1.1775317 (4 pages) | Cited 4 times

Online Publication Date: 26 July 2004

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The intensity of the optical electric field in the vicinity of a corrugated Ni interface is evaluated in the presence of surface plasmons. A photoacoustic technique is used to measure the energy absorbed by the sample which together with a simultaneous conventional measurement of reflectance allows determination of the total energy flow into and out of the interface. The value of the optical electric field is then evaluated on the basis of energy conservation and found to be intensified by a factor of 2.5 as surface plasmons are resonantly generated.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
42.79.Dj Gratings
back to top MICROSCOPY AND IMAGING

Stabilized atomic force microscopy imaging in liquids using second harmonic of cantilever motion for setpoint control

Jens Schiener, Susanne Witt, Martin Stark, and Reinhard Guckenberger

Rev. Sci. Instrum. 75, 2564 (2004); http://dx.doi.org/10.1063/1.1777405 (5 pages) | Cited 8 times

Online Publication Date: 26 July 2004

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We present an automated stabilization of the imaging process in tapping mode atomic force microscopy. For biological applications, the requirement of stable imaging conditions to achieve reliable high resolution is contradicted by the necessity to work in solution to ensure biological functionality: thermal and saline variations of the viscosity, in particular when exchanging the solution the sample is surrounded with, strongly affect the cantilever motion rendering the imaging process instable. Using anharmonic contributions in the deflection signal, the amplitude setpoint is controlled to compensate for unavoidable drift in the free oscillation. By this additional feedback, the tip–sample interaction is maintained stable at a low value, making the instrument robust against drift and tolerant to environmental changes. As a delicate test sample, the “single ring”-mutant of the bacterial chaperonin GroEL from E. coli was imaged. To prove the efficiency of our setup, we show highly stabilized, continuous imaging with minimized user interaction while strong perturbations by exchange of the buffer solution were imposed during the scanning.
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07.79.Lh Atomic force microscopes
87.14.E- Proteins
87.15.K- Molecular interactions; membrane-protein interactions
87.80.-y Biophysical techniques (research methods)
back to top CONDENSED MATTER; MATERIALS

New approach for the measurement of damping properties of materials using the Oberst beam

Jean-Luc Wojtowicki, Luc Jaouen, and Raymond Panneton

Rev. Sci. Instrum. 75, 2569 (2004); http://dx.doi.org/10.1063/1.1777382 (6 pages) | Cited 11 times

Online Publication Date: 26 July 2004

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The Oberst method is widely used for the measurement of the mechanical properties of viscoelastic or damping materials. The application of this method, as described in the ASTM E756 standard, gives good results as long as the experimental set-up does not interfere with the system under test. The main difficulty is to avoid adding damping and mass to the beam owing to the excitation and response measurement. In this paper, a method is proposed to skirt those problems. The classical cantilever Oberst beam is replaced by a double sized free-free beam excited in its center. The analysis is based on a frequency response function measured between the imposed velocity at the center (measured with an accelerometer) and an arbitrary point on the beam (measured with a laser vibrometer). The composite beam (base beam + material) properties are first extracted from the measurement by an optimization algorithm. Young’s modulus and structural damping coefficient of the material under test can be deduced using classical formulations of the ASTM E756 standard for typical materials or using a finite element model for more complex cases. An application to a thick and soft viscoelastic material is presented, the results are shown to be consistent with Kramers–Kronig relations.
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46.70.De Beams, plates, and shells
46.35.+z Viscoelasticity, plasticity, viscoplasticity
46.25.Cc Theoretical studies
back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Quantum-based microwave power measurements: Proof-of-concept experiment

T. P. Crowley, E. A. Donley, and T. P. Heavner

Rev. Sci. Instrum. 75, 2575 (2004); http://dx.doi.org/10.1063/1.1771501 (6 pages) | Cited 5 times

Online Publication Date: 27 July 2004

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We present an initial proof-of-concept experiment to measure microwave power based on quantum-mechanical principles. Ground-state cesium atoms exposed to microwaves at 9.192 631 770 GHz oscillate between two hyperfine states at a rate that is proportional to the rf magnetic field strength. This provides a quantum-based method of measuring rf field strength that depends only on the fundamental parameters in the proportionality constant. A small fountain apparatus was used to prepare laser-cooled cesium atoms in a single hyperfine state, which were then launched through a cylindrical cavity operating in the TE011 mode. After passing through the cavity, the fraction of atoms in the two hyperfine states was measured. Rabi oscillations between the two states were observed as a function of microwave field strength. The scaling with field strength and with time in the cavity agreed with theory to within 0.4%. The field strength in the cavity was used, together with measured S parameters, to determine the microwave power incident at a reference plane outside the fountain apparatus. The difference between the quantum-based microwave power measurement and a traditional microwave power measurement was less than 5% of the measured power.
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07.55.Ge Magnetometers for magnetic field measurements
07.68.+m Photography, photographic instruments; xerography
37.10.De Atom cooling methods
37.10.Gh Atom traps and guides
32.30.Rj X-ray spectra
back to top GENERAL INSTRUMENTS

Novel approach to tensile testing of micro- and nanoscale fibers

E. P. S. Tan and C. T. Lim

Rev. Sci. Instrum. 75, 2581 (2004); http://dx.doi.org/10.1063/1.1775309 (5 pages) | Cited 25 times

Online Publication Date: 27 July 2004

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Due to the strength and size of the micro- and nanoscale fibers, larger conventional universal testing machines are not suitable in performing stretch test of such fibers. Existing microtensile testing machines are custom-made and are complex and expensive to construct. Here, a novel method of using an existing atomic force microscope (AFM)-based nanoindenation system for the tensile testing of microscale or bundled nanoscale fibers is proposed. The microscale poly (L-lactic-co-glycolic acid) fiber ( ∼ 25 μm diameter) was used as an example to illustrate this technique. The microfiber was first attached to a nanoindenter tip and the base via a custom-made holder to ensure that the microfiber was taut and vertically aligned. The force transducer of the nanoindenter was used to measure the tensile force required to stretch the microfiber. The microfiber was stretched using the stepper motor of the AFM system. The elongation of the microfiber was measured by subtracting the elongation of the transducer spring from the total elongation of the microfiber and transducer spring. A plot of the load against elongation of the microfiber was then obtained. The stress and strain of the microfiber was measured by subtracting the elongation of the transducer spring from the total elongation of the microfiber was then obtained. The stress and strain of the microfiber was obtained by dividing the load and elongation by cross-sectional area and gauge length, respectively. With this data, the mechanical behavior of the sample at small strains can be studied. This system is able to provide a high load resolution of 80 nN and displacement resolution of 0.5 nm. However, maximum load and sample elongation is limited and handling of the sample still remains a challenge.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.40.Lm Deformation, plasticity, and creep
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.70.Bt Mechanical testing, impact tests, static and dynamic loads
62.20.F- Deformation and plasticity
62.20.M- Structural failure of materials
back to top NUCLEAR PHYSICS, FUSION AND PLASMAS

Determining the equation-of-state isentrope in an isochoric heated plasma

M. E. Foord, D. B. Reisman, and P. T. Springer

Rev. Sci. Instrum. 75, 2586 (2004); http://dx.doi.org/10.1063/1.1775313 (4 pages) | Cited 2 times

Online Publication Date: 27 July 2004

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A novel method for determining the equation-of-state (EOS) along the release isentrope in an isochoric (constant volume) heated plasma is presented. This approach is demonstrated using simulations of a solid density, 10 eV expanding Al plasma. Determining the material EOS data is validated to pressures near 80 Mbar, much higher than current isentropic compression experiments allow. Limitations at very high temperature (Te ≥ 100 eV), due to the formation of a radiative conduction layer near the rarefaction interface, are also discussed.
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52.65.-y Plasma simulation
52.25.-b Plasma properties
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Line ratio method for measurement of magnetic field vector using Li-multiplet (2 2S−2 2P) emission

A. A. Korotkov, P. D. Morgan, J. Vince, and J. Schweinzer

Rev. Sci. Instrum. 75, 2590 (2004); http://dx.doi.org/10.1063/1.1763250 (13 pages) | Cited 3 times

Online Publication Date: 27 July 2004

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A method has been developed, for use in magnetic confinement devices, to measure the magnetic field vector math in plasmas or gases. It utilizes the intensities of the π and σ components of the resonance multiplet emitted by lithium atoms subjected to a strong Zeeman effect. A difference in dependence of these intensities on the inclination angle θ between math and the line of sight allows one to determine the direction of math, provided the intensity ratio of the π and σ components ξ(θ) is measured. The magnitude of math is routinely inferred from the width of the multiplet. The principles of the measurement are elaborated in detail for the case of a fast Li beam (20–100 keV) used to diagnose a fusion plasma. The deviation of the population of the m states from the statistical one due to a dominant direction for the relative velocity during the excitation of the atoms by plasma ions has been analyzed and corrections to ξ(θ) are calculated. The geometry employed for the measurement is investigated in order to minimize the uncertainties due to systematic and random errors. A procedure for in situ calibration is outlined. As proof of the principle the results from poloidal magnetic field measurements in ohmic and H-mode pulses on the Joint European Torus are analyzed. As expected, much higher components of the poloidal magnetic field BZ and BR have been found at the plasma edge in H-mode pulses indicating the sensitivity of the measurements to the bootstrap current. An accuracy of 10–20% for the poloidal magnetic field component BZ and BR and 1% for B has been reached. Reasonable agreement has been observed between the expected and obtained accuracy. The uncertainty in ξ(θ) is found to be close to the statistical limit at ξ(θ)>6%. The prospects for current density measurement at the plasma edge, which remains a key issue for achieving advanced performance of modern tokamaks, are examined in terms of making use of the developed technique. It is concluded that prospects are good provided the best available Li-beam guns, with equivalent neutral current ∼5 mA, are used. © 2004 American Institute of Physics.
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52.55.Fa Tokamaks, spherical tokamaks
52.25.-b Plasma properties
back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Simple induction probe electric field meter for the detection of electrical fields generated by ion-optical electrodes

Matthew F. Appel, J Ryan McKeachie, Wytze E. van der Veer, and Thorsten Benter

Rev. Sci. Instrum. 75, 2603 (2004); http://dx.doi.org/10.1063/1.1765751 (5 pages) | Cited 1 time

Online Publication Date: 27 July 2004

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A simple electric field probe was developed and used to assess the electrical fields produced inside an ion-optical system. When attached to an XYZ translation stage, this induction probe electrometer is capable of spatially mapping the electrical fields generated by a variety of ion-optical arrangements. Measurements of the electrical fields produced by a conventional reflectron consisting of discrete electrodes and monolithic volume and surface conductive polymeric reflectrons are compared. The performance of the system is validated and a correction is introduced to compensate for capacitive coupling between the probe and the electrode system investigated. © 2004 American Institute of Physics.
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07.68.+m Photography, photographic instruments; xerography
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
41.85.-p Beam optics
back to top MICROSCOPY AND IMAGING

On the stability of Besocke-type scanners

N. Pertaya, K.-F. Braun, and K.-H. Rieder

Rev. Sci. Instrum. 75, 2608 (2004); http://dx.doi.org/10.1063/1.1688439 (5 pages) | Cited 8 times

Online Publication Date: 27 July 2004

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A widespread used construction for the coarse approach mechanism in scanning probe microscopy is the Besocke beetle type. Using stick-slip motion the scanner can thereby be positioned on the millimeter scale horizontally and vertically. This apparent advantage of a high flexibility is bought on the expense of a reduced mechanical stability. Here we present an analysis of the vibrational response of a beetle-type scanner and based on this, a very stable optimized scanner setup. In this setup, shear stack piezoelectric elements are used resulting in very high mechanical resonance frequencies and overall stability. © 2004 American Institute of Physics.
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07.79.-v Scanning probe microscopes and components
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
43.38.Fx Piezoelectric and ferroelectric transducers
back to top THERMOMETRY; THERMAL DIFFUSIVITY; ACOUSTIC; PHOTOTHERMAL AND PHOTOACOUSTIC

A new method to measure viscosity and intrinsic sound velocity of liquids using impedance tube principles at sonic frequencies

Behic Mert, Hartono Sumali, and Osvaldo H. Campanella

Rev. Sci. Instrum. 75, 2613 (2004); http://dx.doi.org/10.1063/1.1771489 (7 pages) | Cited 3 times

Online Publication Date: 28 July 2004

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The attenuation of the sound energy produced by a liquid contained in a cylindrical tube (wave guide) depends on the liquid’s viscosity, sound frequency, tube wall thickness, and tube material. By measuring the acoustic impedance of plane sound waves in a cylindrical wave guide, one can obtain the liquid’s viscosity. Impedance measurements can also provide sound velocity in the liquid medium as another important physical characteristic. In this study a method using the impedance tube technique is presented. This research details the instrument’s principles of operation along pertinent analytical equations and reports experimental results conducted using viscosity standard liquids. It is shown that the instrument can measure both liquid’s viscosity and intrinsic sound velocity with reasonable precision.
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43.58.Dj Sound velocity
43.55.Ev Sound absorption properties of materials: theory and measurement of sound absorption coefficients; acoustic impedance and admittance
43.58.Bh Acoustic impedance measurement
83.85.Jn Viscosity measurements
66.20.-d Viscosity of liquids; diffusive momentum transport
47.80.-v Instrumentation and measurement methods in fluid dynamics
back to top CHEMISTRY

Direct use of the mass output of a thermobalance for controlling the reaction rate of solid-state reactions

M. J. Diánez, L. A. Pérez Maqueda, and J. M. Criado

Rev. Sci. Instrum. 75, 2620 (2004); http://dx.doi.org/10.1063/1.1775318 (5 pages) | Cited 5 times

Online Publication Date: 28 July 2004

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Sample controlled thermal analysis equipment has been developed constituted by an electrobalance in which the mass output (TG signal) is directly used for monitoring the temperature of thermal decomposition reactions under constant rate thermal analysis (CRTA) or stepwise isothermal analysis (SIA) control. The sample weight is programmed to follow a preset linear decrease as a function of the time by means of a conventional controller, that at the time control a second conventional temperature programmer. The CRTA control is achieved by controlling the temperature is such a way that if the mass input is higher than the setpoint, the temperature increases at a predefined heating rate; while if the mass input is lower than the setpoint, the temperature decreases at a predefined cooling rate. The SIA control is achieved by selecting the run–hold command from the menu of the digital input of the temperature programmer. In such a case, the programmed linear heating schedule is in progress while the sample weight is higher than the setpoint and an isothermal dwell is maintained as soon as the weight becomes lower than the setpoint. The direct use of the mass output for the control provides a higher sensitivity for selecting very low values of constant reaction rates than the more conventional methods using the DTG output as control parameter. The thermal degradation of polyvinye chloride (PVC) has been used for checking the behavior of the equipment here developed, showing that the dehydrochlorination of PVC is controlled either by a nucleation and growth of nuclei or by a random scission of the main chain of the polymer.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
82.35.-x Polymers: properties; reactions; polymerization
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
07.20.-n Thermal instruments and apparatus
back to top CONDENSED MATTER; MATERIALS

Test facility for simultaneous measurement of electrical and thermal contact resistance

Prashant Misra and J. Nagaraju

Rev. Sci. Instrum. 75, 2625 (2004); http://dx.doi.org/10.1063/1.1775316 (6 pages) | Cited 5 times

Online Publication Date: 28 July 2004

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A test setup has been developed for simultaneously evaluating the electrical contact resistance (ECR) and thermal contact resistance/conductance (TCR/TCC) across meta–metal contacts at different contact pressures and mean interface temperatures. ECR and TCC across brass–brass contacts in vacuum have been measured simultaneously at different contact pressures and mean interface temperatures. The results obtained are found to be in agreement with the theoretical models available in the literature for ECR and TCC, independently from each other. The maximum absolute uncertainties in the measurement of ECR and TCC with the present setup are estimated to be ±0.003% and ±4.4%, respectively. Apart from contact resistance measurements, the setup is also used to determine thermal conductivity of unknown materials viz., oxygen-free high-conductivity copper and brass, at different temperatures.
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73.40.Cg Contact resistance, contact potential
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
73.40.Jn Metal-to-metal contacts

Spectroscopic cell for fast pressure jumps across the glass transition line

R. Di Leonardo, T. Scopigno, G. Ruocco, and U. Buontempo

Rev. Sci. Instrum. 75, 2631 (2004); http://dx.doi.org/10.1063/1.1763253 (7 pages)

Online Publication Date: 28 July 2004

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We present an experimental protocol for the spectroscopic study of the dynamics of glasses in the aging regime induced by sudden pressure jumps (crunches) across the glass transition line. The sample, initially in the liquid state, is suddenly brought in the glassy state, and therefore out of equilibrium, in a four-window optical crunch cell which is able to perform pressure jumps of 3 Kbar in a time interval of ≈10 ms. The main advantages of this setup with respect to previous pressure-jump systems is that the pressure jump is induced through a pressure transmitting fluid mechanically coupled to the sample stage through a deformable membrane, thus avoiding any flow of the sample itself in the pressure network and allowing us to deal with highly viscous materials. The dynamics of the sample during the aging regime is investigated by Brillouin light scattering. For this purpose the crunch cell is used in conjunction with a high resolution double monochromator equipped with a charge-coupled device detector. This system is able to record a full spectrum of a typical glass forming material in a single 1 s shot. As an example we present the study of the evolution toward equilibrium of the infinite frequency longitudinal elastic modulus (M∞) of low molecular weight polymer [Poly(bisphenol A-co-epichlorohydrin), glycidyl end capped]. The observed time evolution of M∞, well represented by a single stretched exponential, is interpreted within the framework of the Tool–Narayanaswamy theory. © 2004 American Institute of Physics.
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64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
78.35.+c Brillouin and Rayleigh scattering; other light scattering
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Recoil ion momentum spectroscopy using magneto-optically trapped atoms

H. Nguyen, X. Fléchard, R. Brédy, H. A. Camp, and B. D. DePaola

Rev. Sci. Instrum. 75, 2638 (2004); http://dx.doi.org/10.1063/1.1775310 (10 pages) | Cited 13 times

Online Publication Date: 29 July 2004

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A novel apparatus has been developed in which atoms in a magneto-optical trap are used as targets in ion-atom collision experiments. The apparatus is an extension of earlier methodology in which the momentum of the recoiling target is measured and used to deduce the collision Q value and projectile scattering angle. In the present work, the low temperature of the target atoms yields increased momentum resolution, which in turn leads to improved Q value and scattering angle resolution. In addition, because the trapping process leaves some fraction of the atoms in an excited state, the new methodology is ideal for the study of collisions with excited targets. The prototypical system presented is low energy charge transfer between singly charged alkali ions and trapped rubidium atoms in the ground and first excited state.
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82.30.Fi Ion-molecule, ion-ion, and charge-transfer reactions
34.35.+a Interactions of atoms and molecules with surfaces
07.81.+a Electron and ion spectrometers
back to top CHEMISTRY

Development of a measurement system of OH reactivity in the atmosphere by using a laser-induced pump and probe technique

Yasuhiro Sadanaga, Ayako Yoshino, Keisuke Watanabe, Atsushi Yoshioka, Yoko Wakazono, Yugo Kanaya, and Yoshizumi Kajii

Rev. Sci. Instrum. 75, 2648 (2004); http://dx.doi.org/10.1063/1.1775311 (8 pages) | Cited 10 times

Online Publication Date: 29 July 2004

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A novel instrument for measuring OH reactivity in the troposphere has been developed by using a laser-induced pump and probe technique. Air was introduced into a flow tube and OH was produced artificially using O3 photolysis by 266 nm laser. The OH decay rate in the flow tube was monitored by the time-resolved laser-induced fluorescence technique. In this article, the instrument, that is, the measurement principle, the flow tube and the fluorescence detection cell, is presented in detail. Interference by absorption of the 266 nm laser light by O3, and photolysis of NO2 and HCHO was found to be negligible. The influence of recycled OH from the HO2+NO reaction on the measured OH reactivity was estimated by a box model calculation. The systematic error of the measured decay rate was found to be less than 5% even in high NO condition ([NO] = 20 ppbv). The dependence of the measured decay rate on the flow rate in the reaction tube was investigated. A slight change in the total flow rate does not influence the measured decay rate in our experimental condition. The second-order rate coefficients of the OH+CO reactions were measured in order to confirm the accuracy of the measured OH decay rate. The measured rate coefficients were agreed excellently with the recent recommended values. The results of observations in our institute are briefly presented.
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82.33.Tb Atmospheric chemistry
82.50.-m Photochemistry
93.85.-q Instruments and techniques for geophysical research: Exploration geophysics
back to top NUCLEAR PHYSICS, FUSION AND PLASMAS

Single sideband modulator, a key component of Tore-Supra heterodyne reflectometers

R. Sabot, C. Bottereau, J.-M. Chareau, F. Clairet, and M. Paume

Rev. Sci. Instrum. 75, 2656 (2004); http://dx.doi.org/10.1063/1.1777379 (4 pages) | Cited 4 times

Online Publication Date: 29 July 2004

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Although single sideband modulation offers a simple solution to active heterodyne devices and is common in devices working over 150 GHz, it has been scarcely used for reflectometers. For a few years, large bandwidth (12–20 GHz), high performance single sideband modulators (SSBM) have been available. For higher frequency application, a sideband rejection around −25 dBc seems necessary to ensure that the image sideband amplitude remains low after a frequency multiplier. A SSBM provided by Miteq Company presents high enough rejection levels to be assembled with frequency multipliers. Based on this SSBM, we developed a simple microwave scheme suitable for all Tore-Supra reflectometers—from 50 to 155 GHz, dedicated either to density profile reconstruction or to density fluctuation measurements. Compared to the double sideband modulator previously used, SSBM offers higher signal to noise ratio and enables fixed frequency measurements, paving the way for new measurement techniques.
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52.70.Gw Radio-frequency and microwave measurements
52.55.Fa Tokamaks, spherical tokamaks
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
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