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Dec 2000

Volume 71, Issue 12, pp. 4361-4685

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Low-cost optical instrumentation for biomedical measurements

Yordan Kostov and Govind Rao

Rev. Sci. Instrum. 71, 4361 (2000); http://dx.doi.org/10.1063/1.1319859 (14 pages) | Cited 15 times

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Low-cost instruments for measurement in medicine, biotechnology, and environmental monitoring are presented. Recent developments in optoelectronic technology enable practical compact designs. This article presents the available types of light emitters, detectors, and wavelength selection components that are used in low-cost instruments. The main spectroscopic techniques (absorption, reflectance, luminescence intensity, lifetime, and polarization, evanescent wave and surface plasmon resonance) that are used with these instruments are described. Numerous examples of devices for a broad variety of biomedical measurements are presented. © 2000 American Institute of Physics.
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01.30.Rr Surveys and tutorial papers; resource letters
87.64.-t Spectroscopic and microscopic techniques in biophysics and medical physics
42.62.Be Biological and medical applications
87.63.L- Visual imaging
07.60.Rd Visible and ultraviolet spectrometers
42.72.-g Optical sources and standards
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
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back to top OPTICS; ATOMS and MOLECULES; SPECTROSCOPY

Two-dimensional x-ray focusing from compound lenses made of plastic

M. A. Piestrup, J. T. Cremer, H. R. Beguiristain, C. K. Gary, and R. H. Pantell

Rev. Sci. Instrum. 71, 4375 (2000); http://dx.doi.org/10.1063/1.1326051 (5 pages) | Cited 12 times

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We have measured the intensity profile and transmission of x rays focused by a series of either spherical or parabolic lenses fabricated using Mylar® (C5H4O2) or Kapton® (polyimide). The use of plastics can extend the range of operation of compound refractive lenses, improving transmission and aperture size and reducing focal length. The number of unit lenses range from 193 to 600 for each compound refractive lens. Two-dimensional focusing was obtained for photon energies 8–14 keV with imaging distances of less than 1 m. For example, full-width-half-maximum linewidths down to 16 μm at a distance of only 47 cm from the lens were achieved at 9 keV. The effective apertures of the refractive lenses were measured between 250 and 364 μm with peak transmissions between 10% and 33%. © 2000 American Institute of Physics.
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41.50.+h X-ray beams and x-ray optics
42.79.Bh Lenses, prisms and mirrors

X-ray parabolic collimator with depth-graded multilayer mirror

V. V. Protopopov, V. A. Shishkov, and V. A. Kalnov

Rev. Sci. Instrum. 71, 4380 (2000); http://dx.doi.org/10.1063/1.1327305 (7 pages) | Cited 1 time

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A very reliable and easily adjustable x-ray parabolic collimator with uniform intensity distribution in its output cross section is designed using the technology of depth-graded multilayer mirrors. The W/C multilayer mirror structure was specially designed so as to compensate for the decrease in output intensity at lower grazing angles. The advantages of depth-graded multilayer mirrors with respect to laterally graded ones are inexpensive and versatile technology, the absence of any need of precise axial adjustment along the parabolic profile, and the possibility of creating any desired reflection curve shape. With a focal length of 1015 mm and a source projection of 0.1 mm, the total angular divergence of the output beam was measured to be 25 angular seconds at Cu Kα radiation, i.e., only 5 arcsec larger than the theoretical limit. The total output flux at both the Cu Kα1 and Cu Kα2 lines is a factor of 50 larger than that delivered by a conventional Si(111) monochromator. © 2000 American Institute of Physics.
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07.85.-m X- and γ-ray instruments
42.79.Bh Lenses, prisms and mirrors
42.79.Ag Apertures, collimators

New setup for angular distribution measurements of Auger electrons from fixed in space molecules

R. Guillemin, E. Shigemasa, K. Le Guen, D. Ceolin, C. Miron, N. Leclercq, K. Ueda, P. Morin, and M. Simon

Rev. Sci. Instrum. 71, 4387 (2000); http://dx.doi.org/10.1063/1.1327310 (8 pages) | Cited 19 times

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A new experimental setup for measurement of the angular distributions of energy selected Auger electrons emitted from fixed in space molecules is presented. The system is based on two identical ion detectors with a small angular acceptance placed at 0° and 90° relative to the polarization axis of the incident radiation, and a high luminosity double-toroidal electron analyzer combined with position sensitive detection. This setup allows selection of the molecular alignment for σ and π ionization channels simultaneously and provides an energy and ejection angle measurement of the outgoing electron. The performance in terms of energy and angular resolution, as well as the calibration procedure, are discussed. Sample results obtained on the carbon monoxide ionized above the C 1s threshold are presented. © 2000 American Institute of Physics.
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07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment
07.81.+a Electron and ion spectrometers
33.80.Eh Autoionization, photoionization, and photodetachment

A molecular beam/surface spectroscopy apparatus for the study of reactions on complex model catalysts

J. Libuda, I. Meusel, J. Hartmann, and H.-J. Freund

Rev. Sci. Instrum. 71, 4395 (2000); http://dx.doi.org/10.1063/1.1318919 (14 pages) | Cited 34 times

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We describe a newly developed ultrahigh vacuum (UHV) experiment which combines molecular beam techniques and in situ surface spectroscopy. It has been specifically designed to study the reaction kinetics and dynamics on complex model catalysts. The UHV system contains: (a) a preparation compartment providing the experimental techniques which are required to prepare and characterize single-crystal based model catalysts such as ordered oxide surfaces or oxide supported metal particles; and (b) the actual scattering chamber, where up to three molecular beams can be crossed on the sample surface. Two beams are produced by newly developed differentially pumped sources based on multichannel arrays. The latter are capable of providing high intensity and purity beams and can be modulated by means of a vacuum-motor driven and computer-controlled chopper. The third beam is generated in a continuous or pulsed supersonic expansion and is modulated via a variable duty-cycle chopper. Angular and time-resolved measurements of desorbing and scattered molecules are performed with a rotatable doubly differentially pumped quadrupole mass spectrometer with a liquid-nitrogen cooled ionizer housing. Time-resolved but angle-integrated measurements are realized with a second nondifferentially pumped quadrupole mass spectrometer. In situ measurements of adsorbed species under reaction conditions are performed by means of an adapted vacuum Fourier transform infrared spectrometer. The spectrometer provides the possibility of time-resolved measurements and can be synchronized with any of the beam sources. This contribution provides a general overview of the system and a description of all new components and their interplay. We also present test data for all components employing simple adsorption/desorption and reaction systems. © 2000 American Institute of Physics.
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34.50.Lf Chemical reactions
37.20.+j Atomic and molecular beam sources and techniques
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
07.75.+h Mass spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
back to top PARTICLE SOURCES, OPTICS and ACCELERATION

Laser-driven atomic-probe-beam diagnostics

B. A. Knyazev, J. B. Greenly, and D. A. Hammer

Rev. Sci. Instrum. 71, 4409 (2000); http://dx.doi.org/10.1063/1.1324738 (6 pages) | Cited 1 time

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A new laser-driven atomic-probe-beam diagnostic (LAD) is proposed for local, time-resolved measurements of electric field and ion dynamics in the accelerating gap of intense ion beam diodes. LAD adds new features to previous Stark-shift diagnostics which have been progressively developed in several laboratories, from passive observation of Stark effect on ion species or fast (charge-exchanged) neutrals present naturally in diodes, to active Stark atomic spectroscopy (ASAS) in which selected probe atoms were injected into the gap and excited to suitable states by resonant laser radiation. The LAD scheme is a further enhancement of ASAS in which the probe atoms are also used as a local (laser-ionized) ion source at an instant of time. Analysis of the ion energy and angular distribution after leaving the gap enables measurement, at the chosen ionization location in the gap, of both electrostatic potential and the development of ion divergence. Calculations show that all of these quantities can be measured with sub-mm and ns resolution. Using lithium or sodium probe atoms, fields from 0.1 to 10 MV/cm can be measured. © 2000 American Institute of Physics.
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52.75.Fk Magnetohydrodynamic generators and thermionic convertors; plasma diodes
07.77.Ka Charged-particle beam sources and detectors
52.70.Ds Electric and magnetic measurements

Computer optimization for high-resolution time-of-flight mass spectrometer

U. Even and Bernhard Dick

Rev. Sci. Instrum. 71, 4415 (2000); http://dx.doi.org/10.1063/1.1322583 (6 pages) | Cited 12 times

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We describe the theoretical computation, and provide construction details, of a high-resolution time-of-flight mass spectrometer that can replace reflectrons in many applications. © 2000 American Institute of Physics.
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07.75.+h Mass spectrometers
41.85.-p Beam optics
02.60.Pn Numerical optimization
07.05.Tp Computer modeling and simulation

Optimization of a one-dimensional time-of-flight mass spectrometer

Uzi Even and Bernhard Dick

Rev. Sci. Instrum. 71, 4421 (2000); http://dx.doi.org/10.1063/1.1322584 (10 pages) | Cited 3 times

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Space focusing of a linear time-of-flight mass spectrometer (TOFMS) with an arbitrary number N of ion acceleration regions, a field free drift tube, and a reflectron is analyzed. A quality function Q(d,u0) is defined as the fractional error in the flight time of an ion with initial position d and initial velocity u0 with respect to an ion with d = 0 and u0 = 0. This quality function has the form Q(d,u0) = −u0/f(0)+F(u02−d), where the function f(y) depends on the dimensions and the field strengths chosen for the instrument, and F(y) = f(y)/f(0)−1. The quality function is optimized up to the order k by setting all Taylor coefficients of F(y) up to and including yk equal to zero and solving this system of equations for the design parameters of the instrument. A linear TOFMS with N acceleration regions can be optimized in this way with respect to N design parameters. An additional reflectron will not add another optimizable parameter, i.e., no further Taylor coefficient can be made to vanish. After optimization of the TOFMS with respect to all field strengths including that in the reflectron, the quality function becomes independent of the length of the field free drift tube. Hence, the effect of the reflectron is to make space focusing independent from the drift tube length. The quality function for a fully optimized TOFMS depends only on the number N of acceleration stages and is, for a given N, identical for the designs with and without a reflectron. However, the design containing a reflectron has a smaller value of the factor 1/f(0) which determines the error introduced by the initial velocity distribution of the ions. A space focused TOFMS cannot be further focused with respect to the initial velocity u0, since the first term in the Taylor expansion of the quality function in the variable u0 is proportional to the inverse of the total flight time. For a TOFMS with two or more acceleration regions this is the dominant source of error that remains after space focusing. This situation cannot be improved by delayed or pulsed extraction of the ions from the ionization region nor by deceleration of the ions before they enter the field free region. © 2000 American Institute of Physics.
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07.75.+h Mass spectrometers

A pulsed supersonic entrainment reactor for the rational preparation of cold ionic complexes

W. H. Robertson, J. A. Kelley, and M. A. Johnson

Rev. Sci. Instrum. 71, 4431 (2000); http://dx.doi.org/10.1063/1.1326931 (4 pages) | Cited 50 times

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We describe an ion source for the efficient preparation of cold ion-molecule complexes, X−⋅M. The method relies on condensation of solvent molecules, M, onto argon-solvated ions, X−⋅Arm, where the X−⋅Arm species are formed in a primary expansion and the molecular partner, M, is interfaced to this flow in the hydrodynamic region by supersonic entrainment. This hybrid “supersonic afterglow” reactor provides a clean synthetic approach for both bare and argon-solvated complexes, where the latter are particularly useful since their structures can be characterized by “nanomatrix” infrared predissociation spectroscopy. © 2000 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
82.30.Nr Association, addition, insertion, cluster formation
34.80.Lx Recombination, attachment, and positronium formation
36.40.-c Atomic and molecular clusters

Characteristics and design of metal vacuum arc plasma source power supply for pulsed-mode plasma immersion ion implantation

L. P. Wang, K. Y. Gan, X. B. Tian, B. Y. Tang, and P. K. Chu

Rev. Sci. Instrum. 71, 4435 (2000); http://dx.doi.org/10.1063/1.1327312 (3 pages) | Cited 3 times

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Metal vacuum arc plasma sources enhance the capability of plasma immersion ion implantation (PIII) by providing a convenient and efficient means by which to introduce metallic ions into the plasma for metallic ion implantation and/or thin film deposition. The power supply of a metal vacuum arc plasma source is usually based on the artificial transformation line design, but it has several drawbacks. For instance, the pulse width cannot be adjusted conveniently and the pulsing frequency cannot exceed a predefined value. These restrictions make process optimization and synchronization with the sample high voltage modulator complicated in pulsed-mode PIII operation. In this work, we experimentally investigate the voltage–current characteristics of our metal vacuum arc plasma source. Our results suggest two different power supply designs. By adopting the design incorporating a gradual voltage–current decline, we successfully construct a simple and reliable power supply that works in a stable manner for a prolonged period of time. © 2000 American Institute of Physics.
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
52.50.Dg Plasma sources
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
back to top NUCLEAR PHYSICS, FUSION and PLASMAS

Reduction of the source size of gas-puff z-pinch plasmas using an inductive pulsed power system

K. Imasaka, K. Kawazoe, K. Kawauchi, S. Hara, J. Suehiro, and M. Hara

Rev. Sci. Instrum. 71, 4438 (2000); http://dx.doi.org/10.1063/1.1322576 (7 pages) | Cited 3 times

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A small scale inductive pulsed power (IPP) generator with copper wire fuses as an opening switch has been applied to an argon gas-puff z-pinch plasma which can be used as a point source for x-ray lithography. The IPP generator with fuses supplies a driving current of 60 kA in 400 ns to the z-pinch plasma. Without fuses, the generator serves as a conventional fast bank (FB) system which supplies z-pinch current of 60 kA in 4.5 μs. Characteristics of the z-pinch implosions in IPP and FB systems are investigated and compared. The result obtained shows that the intensity of soft x rays emitted from hot spots in both systems is decreased gradually with longer delay time, which is the time difference between energizing a gas-puff actuator and a primary current trigger. Dual axis pinhole imagery shows that the hot spot size is 0.8 mm in diameter in both systems. However, the average radial displacement of hot spots is 0.9 mm in the FB system and it is reduced to 0.4 mm in the IPP system. Optical framing camera images have confirmed that the radial distribution of hot spots is due to kink instability. The framing images also show that the imploding plasma in the FB system which has a pinch size of 2.2 mm in diameter can be further compressed to 1.3 mm. The IPP system can suppress the kink instability of pinch plasma and increases plasma column uniformity along the z axis. This suggests that the IPP system can improve the stability of the pinched plasma so as to minimize the end-on source size for x-ray lithography applications. © 2000 American Institute of Physics.
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52.55.Ez Theta pinch
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
85.40.Hp Lithography, masks and pattern transfer

A filter bank system for scattered spectrum analysis in collective Thomson scattering diagnostic on JT-60

S. Lee, T. Kondoh, Y. Yonemoto, and Y. Miura

Rev. Sci. Instrum. 71, 4445 (2000); http://dx.doi.org/10.1063/1.1326932 (4 pages) | Cited 3 times

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In JT-60, a collective Thomson scattering (CTS) diagnostic system based on a pulsed CO2 laser (wavelength 10.6 μm, beam energy 15 J, pulse width 1 μs) has been developed to measure ion temperature and velocity distribution of fast ions to demonstrate the feasibility of measurements of confined alpha particles. A high power pulsed CO2 laser and heterodyne receiver system using a quantum-well infrared photodetector (QWIP) has been developed and installed in the diagnostic room. In order to resolve frequency distribution of pulsed scattered light (1 μs), we developed a wideband filter bank system (0.4–4.5 GHz) for scattered spectrum analysis in JT-60 CTS diagnostic. The detector bandwidth and frequency resolution are both determined by the calculation results of expected scattered spectrum. In order to realize wideband multichannel detection, cascade connected seventh order simultaneous-Chebyshev (elliptic) bandpass filters were adopted. Signal to noise ratio based on the noise equivalent power of the QWIP receiver and laser pulse length are also evaluated. © 2000 American Institute of Physics.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.55.Fa Tokamaks, spherical tokamaks
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
07.68.+m Photography, photographic instruments; xerography
52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
85.60.Gz Photodetectors (including infrared and CCD detectors)
84.30.Vn Filters
back to top MICROSCOPY and IMAGING

Development of a high-resolution x-ray imaging system with a charge-coupled-device detector coupled with crystal x-ray magnifiers

K. Sato, Y. Hasegawa, K. Kondo, K. Miyazaki, T. Matsushita, and Y. Amemiya

Rev. Sci. Instrum. 71, 4449 (2000); http://dx.doi.org/10.1063/1.1322588 (8 pages) | Cited 2 times

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A high-spatial-resolution x-ray imaging system for microscopic use has been developed, which utilizes a charge-coupled-device (CCD) detector as an imaging device. The spatial resolution of the x-ray CCD detector with Gd2O2S:Tb is 8.0 μm in terms of the full width at half-maximum of the line-spread function with a conversion gain of 0.58 e-h/xph. In order to obtain a higher spatial resolution, x-ray magnifiers based on asymmetric Si(111) Bragg reflections are placed in front of the x-ray CCD detector. The spatial resolution of this imaging system has been improved to 1.2 μm. © 2000 American Institute of Physics.
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07.85.Tt X-ray microscopes
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors

Electrochemically etched nickel tips for spin polarized scanning tunneling microscopy

Massimiliano Cavallini and Fabio Biscarini

Rev. Sci. Instrum. 71, 4457 (2000); http://dx.doi.org/10.1063/1.1311936 (4 pages) | Cited 24 times

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A fast and simple method for the electrochemical preparation of sharp Ni tips for spin polarized scanning tunneling microscopy (STM) is reported. These Ni tips perform well also in conventional STM experiments, being able to achieve reproducible atomic resolution on graphite. Ni tips combine the advantages of both Pt/Ir tips, since they are oxide free, and of W tips because of the greater reproducibility and control of the tip apex by means of the etching protocol, as compared to freshly cut tips. © 2000 American Institute of Physics.
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07.79.Cz Scanning tunneling microscopes
81.65.Cf Surface cleaning, etching, patterning

Plug “n” play scanning probe microscopy

Thomas Michely, Markus Kaiser, and Marcel J. Rost

Rev. Sci. Instrum. 71, 4461 (2000); http://dx.doi.org/10.1063/1.1322587 (7 pages) | Cited 12 times

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A new concept of scanning probe microscopy allows the investigation of arbitrarily positioned and oriented, possibly curved locations situated at large and immobile objects, which cannot be isolated from the environment. The concept is based on the beetle type scanning probe microscope and uses, as a key element, magnetic forces which increase the pressure at the contacts of microscope and object. The magnetic forces are shown to greatly decrease the sensitivity of the microscope to vibrations and acoustic noise from the environment. Sufficiently large magnetic forces make the microscope operation independent from orientation and thereby relieve a decisive constraint for imaging application. The capabilities of the new concept are exemplified for a plug “n” play scanning tunneling microscope. © 2000 American Institute of Physics.
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07.79.Cz Scanning tunneling microscopes
07.79.Pk Magnetic force microscopes

Low temperature magnetic force microscopy with enhanced sensitivity based on piezoresistive detection

A. Volodin, K. Temst, C. Van Haesendonck, and Y. Bruynseraede

Rev. Sci. Instrum. 71, 4468 (2000); http://dx.doi.org/10.1063/1.1322582 (6 pages) | Cited 17 times

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We describe the design and performance of a low temperature magnetic force microscope (MFM) based on commercially available piezoresistive cantilevers. The sensitivity has been increased by exciting the cantilever at a higher (second or third) flexural mode. The operation at higher mechanical resonances allows to improve the signal-to-noise ratio by a factor of 3. Our MFM is particularly advantageous for studying magnetic vortices on the surface of superconductors. The magnetic tip coating was optimized by relying on Co/Au multilayers grown by molecular beam epitaxy. This allows one to keep the interaction with the vortices small, and it becomes possible to observe a stable vortex lattice on the surface of a cleaved NbSe2 crystal. From our measurements of the disordered vortex state in thin Nb films we infer that the magnetic stray field induced by the tip is in the range 0.3–0.5 mT. © 2000 American Institute of Physics.
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07.79.Pk Magnetic force microscopes
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
back to top CONDENSED MATTER; MATERIALS

Photoacoustic cell for spectroscopy at low temperatures

U. Störkel and W. Grill

Rev. Sci. Instrum. 71, 4474 (2000); http://dx.doi.org/10.1063/1.1315350 (5 pages) | Cited 1 time

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Based on the photoacoustic effect we have developed a cell for application in optical spectroscopy at low temperatures (between 1 and 2 K). A superconducting bolometer serves as a detector for temperature waves (so-called second sound) in liquid helium. These waves are generated after transformation of the absorbed light energy into heat due to nonradiative decay in the sample. The cell consists of an elliptical mirror with two focal points, in which the sample and the detector are placed. In this article we show some characteristic properties of the cell. In addition to that we present an absorption spectrum of a doped inorganic glass as a first example of possible applications of the photoacoustic method. © 2000 American Institute of Physics.
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43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
43.58.-e Acoustical measurements and instrumentation
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Apparatus for thin-film stress measurement with integrated four-point bending equipment: Performance and results on Cu films

V. Weihnacht, W. Brückner, and C. M. Schneider

Rev. Sci. Instrum. 71, 4479 (2000); http://dx.doi.org/10.1063/1.1326925 (4 pages) | Cited 9 times

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New insight into the mechanical behavior of thin metallic films on substrates can be obtained by a novel experimental technique. It comprises stress measurements by the wafer curvature technique in combination with a four-point bending of beam-shaped samples. A dedicated apparatus was constructed which allows such experiments in high vacuum between room temperature and 500 °C to be carried out. It has a stress measurement sensitivity better than 0.1 MPa and a long-term stability better than ±0.2 MPa over 24 h in the case of a 1 μm thick film. Strains up to 0.8% could be imposed by a four-point bending on films grown on 380 μm thick Si substrates before cracking of the substrates. Both the thermal cycling and the four-point bending technique were used to investigate the plastic behavior of 1 μm thick Cu films on oxidized Si substrates. © 2000 American Institute of Physics.
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46.80.+j Measurement methods and techniques in continuum mechanics of solids
68.60.Bs Mechanical and acoustical properties

Application of sheet shaped plasma supplemented with radio frequency plasma source for production of thin films

Kanetoshi Shibata, Hiroaki Ito, Noboru Yugami, Yasushi Nishida, and Tadaomi Miyazaki

Rev. Sci. Instrum. 71, 4483 (2000); http://dx.doi.org/10.1063/1.1322579 (6 pages) | Cited 4 times

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Production technique of thin films is described as an application of a sheet shaped electron cyclotron resonance heating plasma supplemented with a radio frequency plasma source for controlling the plasma parameters. The deposition rate of thin films onto the substrate can be varied from 6 to 102 nm/min depending on the experimental conditions under control. The thin film is made uniformly in space over a wide range of plasma parameters. The present plasma source also has typical characteristics of sharp density and temperature gradient at the edge of the sheet plasma to make a uniform, low temperature (Te ⩽ 1 eV) plasma in the outer peripheral region. The present experimental technique could be applicable to the plasma source for material processing such as thin film formation, semiconductor devices such as solar batteries or flat panel display, and so on. © 2000 American Institute of Physics.
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
52.50.Gj Plasma heating by particle beams
52.50.Dg Plasma sources

Thermostatic control of a sample tube in a nuclear magnetic resonance spin-echo spectrometer

A. V. Anisimov and N. R. Dautova

Rev. Sci. Instrum. 71, 4489 (2000); http://dx.doi.org/10.1063/1.1326052 (3 pages) | Cited 1 time

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The equipment is based on the Peltier effect and is designed for thermostatic control of a sample for a nuclear magnetic resonance (NMR) spin-echo spectrometer with a pulsed magnetic field gradient for both relaxation and diffusion measurements within a temperature range −20 °C to +70 °C. A special thermostatically controlled nozzle on the NMR probe enables simultaneous thermostatic control of several samples at a given temperature and to transfer the samples in turn into the NMR probe measuring circuit without contact with the ambient atmosphere. The equipment consists of three independent units connected to the NMR probe and fits modern small-sized NMR spin-echo spectrometers, making NMR experiments significantly cheaper and more efficient. © 2000 American Institute of Physics.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
85.80.Fi Thermoelectric devices
07.07.Tw Servo and control equipment; robots

A shear cell for aligning and measuring birefringence of bow-shaped (banana) liquid crystals

A. Rastegar, G. Wulterkens, H. Verscharen, Th. Rasing, and G. Heppke

Rev. Sci. Instrum. 71, 4492 (2000); http://dx.doi.org/10.1063/1.1288238 (5 pages) | Cited 4 times

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We present a special shear cell for aligning unconventional liquid crystals and performing high temperature optical studies. Sample thicknesses of 1–100 μm in the temperature range of 20–200 °C with a shear amplitude as large as 1 mm are achievable with this cell. The shear cell was used to align banana-shaped liquid crystals and to measure their optical anisotropy in the B2, B3, and B4 phases which was not possible before. The optical anisotropy of the B2 phase slowly increases by cooling and jumps to a low value at the transition to the B3 phase. The optical rotation is almost constant in the B2 phase and increases sharply at the transition to the B3 phase. The B3 and B4 phases are distinguishable by their optical anisotropy. © 2000 American Institute of Physics.
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61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
64.70.M- Transitions in liquid crystals
07.20.Ka High-temperature instrumentation; pyrometers
78.20.Fm Birefringence
78.20.Ek Optical activity

Experimental confirmation of the insensitivity of mass diffusion measurements to blockages and voids along the diffusion path

R. Michael Banish, J. Iwan D. Alexander, and Lyle B. Jalbert

Rev. Sci. Instrum. 71, 4497 (2000); http://dx.doi.org/10.1063/1.1321300 (5 pages) | Cited 2 times

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Using the real-time diffusion methodology first developed by Codastefano et al. [Rev. Sci. Instrum. 48, 1650 (1977)] we show that deviations from strictly one-dimensional transport (i.e., blockages and voids) widely cited in the literature as leading to erroneous results, have little effect on the measured diffusivity. In this methodology, radiotracer, initially located at one end of a cylindrical diffusion sample, is used as the diffusant. The sample is positioned in a concentric isothermal radiation shield with collimation bores located at defined positions along its axis. The intensity of the radiation emitted through the collimators is measured as a function of time using solid state detectors. Diffusivities are calculated from the signal difference between the detectors. These results were obtained using 114mIn radiotracer in benign indium. A 60% blockage was simulated by using a 2 mm source disk diffusing into 3 mm diameter host section. A void/bubble was simulated by inserting a 1 mm diameter by 1 mm long side plug into the sample 7 mm from the top (radiotracer section). The resulting self-diffusivities obtained were, for both modifications, comparable with other ground experiments. These results agree with numerical simulations. An analytical model describing the minimal effects of blockages and voids on the output diffusivity is presented. © 2000 American Institute of Physics.
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07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)
66.10.C- Diffusion and thermal diffusion

Sources and control of instrumental drift in the surface forces apparatus

M. Heuberger, M. Zäch, and N. D. Spencer

Rev. Sci. Instrum. 71, 4502 (2000); http://dx.doi.org/10.1063/1.1319977 (7 pages) | Cited 5 times

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Instrumental drift in the surface forces apparatus (SFA) has been carefully scrutinized. A diversity of different contributions with different characteristic time constants could be distinguished. The face seal of the functional attachment was identified as a potential weak point in the mechanical loop of the instrument. We compared drift in three different design variants and found that the drift rate may vary over four orders of magnitude. We believe that the presented results are applicable to a number of different SFA types. © 2000 American Institute of Physics.
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07.10.Pz Instruments for strain, force, and torque
07.60.Ly Interferometers
07.07.Tw Servo and control equipment; robots

Multi-aperture gasket for experiments at high pressure in a diamond-anvil cell

J. Zhao, G. Hearne, M. Maaza, M. K. Nieuwoudt, and J. D. Comins

Rev. Sci. Instrum. 71, 4509 (2000); http://dx.doi.org/10.1063/1.1326057 (3 pages) | Cited 1 time

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It is possible to study multiple samples which are concurrently at high pressure in a diamond-anvil cell, being convenient for investigations in a single compression or decompression sequence of pressures, if more than one sample cavity is drilled in the gasket. This has been demonstrated in “routine” sub-megabar luminescence experiments to 30–40 GPa and may potentially be extended to the megabar regime under a variety of P-T conditions if smaller sample cavities are utilized. The idea of multiple samples concurrently under high pressure in cavities of the same gasket may find fruitful application in experiments involving, micro-optical (Raman or infrared) spectroscopy, synchrotron x-ray diffraction, and laser-heating investigations, where the probe radiation may be confined to sample regions of less than 50 μm diameter. © 2000 American Institute of Physics.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
06.60.Ei Sample preparation (including design of sample holders)

Real-time determination of thermal diffusivity in a disk-shaped sample: Applications to graphite and boron nitride

Timothée L. Pourpoint, R. Michael Banish, Francis C. Wessling, and Robert F. Sekerka

Rev. Sci. Instrum. 71, 4512 (2000); http://dx.doi.org/10.1063/1.1322586 (9 pages) | Cited 4 times

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We describe a methodology for determining thermal diffusivities in real time by using temperature measurements at only two locations in a cylindrical sample. The technique is based on an analytical solution of heat transfer in a circular cylinder. This methodology does not require knowing the initial temperature increase or any timing between the applied and measured response. Starting with a heated cylindrical region having a unique fraction of the sample radius, and unique temperature measurement locations, the analytical solution for temperature at three specific radii can be approximated, after an initial transient, by a constant plus a single term that decreases exponentially with time. There are three special radii that fulfill the required condition. The data are analyzed by taking logarithms of the differences of the temperature versus time at these three radii, resulting in lines having slopes at large times that are proportional to the thermal diffusivity. Surprisingly, other choices of the size of the heated region and the measurement locations lead to similar results, except with longer transients. Experimental results for graphite and boron nitride agree with our numerical simulations and with the manufacturer’s data. This technique is applicable to solids and to liquids if heat transport due to convection is negligible. © 2000 American Institute of Physics.
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07.20.Dt Thermometers
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
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