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May 2002

Volume 73, Issue 5, pp. 1985-2213

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back to top OPTICS; ATOMS and MOLECULES; SPECTROSCOPY

A monolithic polycapillary focusing optic for polychromatic neutron diffraction applications

D. F. R. Mildner, H. H. Chen-Mayer, W. M. Gibson, T. Gnäupel-Herold, M. E. Miller, H. J. Prask, A. J. Schultz, R. Vitt, and R. Youngman

Rev. Sci. Instrum. 73, 1985 (2002); http://dx.doi.org/10.1063/1.1470236 (9 pages) | Cited 2 times

Online Publication Date: 24 April 2002

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We have conducted measurements at five different thermal neutron wavelengths to determine the transmission characteristics of a tapered monolithic focusing lens with a focal length of 100 mm, suitable for time-of-flight diffraction. Both the width of the focused beam and the intensity gain of the optic increase as a function of wavelength. We have performed similar measurements on a polychromatic beam on a pulsed neutron source, where the results are subject to background from short wavelength neutrons. The use of a beryllium filter shows the increased effective gain for the longer wavelengths at the expense of an increased focused beam width by a factor of 2. © 2002 American Institute of Physics.
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41.85.Si Particle beam collimators, monochromators
61.05.fm Neutron diffraction
07.77.Ka Charged-particle beam sources and detectors

A simple, high power, compact, intracavity frequency-doubled, Q-switched Nd:Y3Al5O12 laser

Scott Christensen, Henry C. Kapteyn, Margaret M. Murnane, and Sterling Backus

Rev. Sci. Instrum. 73, 1994 (2002); http://dx.doi.org/10.1063/1.1469672 (4 pages) | Cited 3 times

Online Publication Date: 24 April 2002

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We have developed a simple, compact, high power, diode-pumped, intracavity frequency-doubled, Nd:Y3Al5O12 laser capable of generating output powers of up to 70 W at 10 kHz, and 16.5 W at 1 kHz. The output beam quality is highly multimode, with an M2 ∼ 30. This, combined with the short output pulse duration of 36–60 ns, and the high average power, makes this laser ideal for pumping ultrafast Ti:sapphire laser amplifier systems. © 2002 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Xi Diode-pumped lasers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.55.Px Semiconductor lasers; laser diodes
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Superheterodyne light beating spectroscopy for Rayleigh–Brillouin scattering using frequency-tunable lasers

Hajime Tanaka and Tsuyoshi Sonehara

Rev. Sci. Instrum. 73, 1998 (2002); http://dx.doi.org/10.1063/1.1469671 (13 pages) | Cited 3 times

Online Publication Date: 24 April 2002

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We developed a new optical superheterodyne method for light scattering using frequency tunable lasers and succeeded in measuring Brillouin spectra of simple liquids in a wide frequency range from 10 MHz to 3 GHz. In this method the speed of a photodetector and electric circuits does not limit the upper frequency bound, since the superheterodyne detection of the signal allows us to shift the optical beat frequency down to a desired fixed frequency suitable for electric signal processing. Thus an almost ultimate signal-to-noise ratio is realized at any phonon frequency. This is a great advantage over conventional optical beating methods. It is realized by the continuous tunability of the frequency of the laser used as a local oscillator light for superheterodyne detection. Our method provides an extremely high frequency resolution (∼300 kHz), which is determined by the stability of an optical frequency difference between the two lasers under its feedback control. We call this method “superheterodyne Brillouin spectroscopy.” The method has a high potential for studying the dynamics in a wide class of transparent condensed matters. © 2002 American Institute of Physics.
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78.35.+c Brillouin and Rayleigh scattering; other light scattering
42.62.Fi Laser spectroscopy

Direct measurement of laser power through a high numerical aperture oil immersion objective lens using a solid immersion lens

Shigeki Matsuo and Hiroaki Misawa

Rev. Sci. Instrum. 73, 2011 (2002); http://dx.doi.org/10.1063/1.1470231 (5 pages) | Cited 7 times

Online Publication Date: 24 April 2002

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For many laser applications, information on irradiated laser power is important. However, direct measurement of laser power through a high numerical aperture objective lens is difficult in a laser microscope. In this article, we propose a method which use a solid immersion lens (SIL) for such measurements. A laser beam focused by an objective lens is introduced to the flat surface of a SIL, emitted through the spherical surface, and then detected. In this way the divergence of the laser beam is reduced, and as a result the detection efficiency of the laser power increases. From theoretical analysis, a Weierstrass-sphere type SIL was found to be an appropriate thickness for this propose. Transmittance of the SIL is evaluated for several refractive indeces. The validity of this method is confirmed experimentally. © 2002 American Institute of Physics.
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42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.79.Bh Lenses, prisms and mirrors
07.60.Pb Conventional optical microscopes
back to top PARTICLE SOURCES, OPTICS and ACCELERATION, DETECTORS

Beam measurements on the H− source and low energy beam transport system for the Spallation Neutron Source

R. Thomae, R. Gough, R. Keller, K. N. Leung, T. Schenkel, A. Aleksandrov, M. Stockli, and R. Welton

Rev. Sci. Instrum. 73, 2016 (2002); http://dx.doi.org/10.1063/1.1470238 (4 pages) | Cited 1 time

Online Publication Date: 24 April 2002

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The ion source and low energy beam transport (LEBT) section of the front-end systems presently being built at Lawrence Berkeley National Laboratory are required to provide 50 mA of H− beam current at a 6% duty factor (1 ms pulses at 60 Hz) with a normalized root mean square emittance of less than 0.20 π mm mrad. Experimental results, including emittance, chopping, and steering measurements, on the performance of the ion source and LEBT system operated at the beam parameters demanded will be discussed. © 2002 American Institute of Physics.
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29.27.Eg Beam handling; beam transport
29.27.Fh Beam characteristics
29.25.Dz Neutron sources
29.25.Ni Ion sources: positive and negative

Compact plasma accelerator device

John E. Foster

Rev. Sci. Instrum. 73, 2020 (2002); http://dx.doi.org/10.1063/1.1464658 (8 pages) | Cited 2 times

Online Publication Date: 24 April 2002

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A compact plasma accelerator concept based on plasma production at a magnetic cusp was designed and fabricated. Plume and discharge characteristics of the device were documented using a Faraday probe and a retarding potential analyzer. The discharge current variations with increasing discharge voltage were nonlinear with the discharge current increasing rapidly with voltage. The device demonstrated the capability of generating ion beamlets (∼80 eV) with downstream peak current densities comparable to that of higher power ion thruster devices (7 mA/cm2). In general, the device appeared to operate best at very low flow rates. High propellant utilization fractions (ionization fractions) were measured below 1 SCCM of Xe flow (88% at 0.48 SCCM). Floating potential measurements made downstream of the device were used to estimate the downstream electric field. These measurements, which were used to qualitatively assess beam neutralization, indicated beam neutralization does occur downstream of the device. Based on the measurements, the compact plasma accelerator concept could potentially be used as a low energy ion source for propulsion applications or for low energy plasma/materials processing applications.
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29.20.-c Accelerators
29.25.Ni Ion sources: positive and negative
07.77.Ka Charged-particle beam sources and detectors
52.75.Di Ion and plasma propulsion
52.50.Dg Plasma sources

Residual images in charged-coupled device detectors

Armin Rest, Lars Mündermann, Ralf Widenhorn, Erik Bodegom, and T. C. McGlinn

Rev. Sci. Instrum. 73, 2028 (2002); http://dx.doi.org/10.1063/1.1470234 (5 pages) | Cited 5 times

Online Publication Date: 24 April 2002

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We present results of a systematic study of persistent, or residual, images that occur in charged-coupled device (CCD) detectors. A phenomenological model for these residual images, also known as “ghosting,” is introduced. This model relates the excess dark current in a CCD after exposure to the number of filled impurity sites which is tested for various temperatures and exposure times. We experimentally derive values for the cross section, density, and characteristic energy of the impurity sites responsible for the residual images. © 2002 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
42.79.Pw Imaging detectors and sensors
85.30.Tv Field effect devices
back to top NUCLEAR PHYSICS, FUSION and PLASMAS

An emissive probe with a rhenium filament for measuring plasma potential in a radio frequency oxygen plasma

E. H. Wilson, Jongtae Jeong, and N. Hershkowitz

Rev. Sci. Instrum. 73, 2033 (2002); http://dx.doi.org/10.1063/1.1469674 (5 pages) | Cited 5 times

Online Publication Date: 24 April 2002

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Plasma potential measurements in a rf inductively coupled oxygen plasma were carried out using an emissive probe with rhenium filaments. Rhenium was chosen because of the remarkable electrical conductivity of its oxide which is 108 times higher than tungsten oxide. Using 75 μm diam filaments hot-wire emissive probe measurements of an oxygen plasma potential were performed in pressures of 3–100 mTorr. Due to surface contaminants, filament conditioning was performed in order to allow electron emission. Analysis of time-averaged current–voltage curves yielded the maximum and minimum of the rf fluctuation in the plasma. Axial profiles of the plasma potential fluctuations at 3.3 mTorr show a nearly linear decrease with the distance from the wall, and demonstrate the feasibility for further investigation of oxygen plasmas using rhenium filaments. © 2002 American Institute of Physics.
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52.70.Ds Electric and magnetic measurements
52.25.Gj Fluctuation and chaos phenomena

Neural networks for real time determination of radiated power in JET

O. Barana, A. Murari, P. Franz, L. C. Ingesson, and G. Manduchi

Rev. Sci. Instrum. 73, 2038 (2002); http://dx.doi.org/10.1063/1.1463714 (6 pages) | Cited 4 times

Online Publication Date: 24 April 2002

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This article describes the use of neural networks (NNs) for the on-line computation of the radiated power in JET. The NNs have been trained using a database of about 120 discharges, for which the emitted power had been calculated via tomographic inversion of JET bolometric signals. In addition to the bolometric data, elongation and triangularity have been used as input to the NN, since these provide useful complementary information. Dedicated NNs have been designed for the determination of the total radiated power, the power from the bulk, and from the divertor region. All the NNs have been tested with a set of about 30 discharges with positive results. Moreover, the NNs can operate at full sampling speed and are therefore suited to follow edge localized modes and other rapid phenomena. The sensitivity of the NNs to failures in the input signals has also been tested, proving their robustness. Their possible use in feedback applications is finally briefly discussed. © 2002 American Institute of Physics.
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28.52.Av Theory, design, and computerized simulation
07.05.Mh Neural networks, fuzzy logic, artificial intelligence
52.55.Fa Tokamaks, spherical tokamaks
52.55.Rk Power exhaust; divertors

Technique for distinguishing and determining the origin of photon emissions from complex plasmas

T. M. Mostefaoui, N. G. Adams, and L. M. Babcock

Rev. Sci. Instrum. 73, 2044 (2002); http://dx.doi.org/10.1063/1.1463716 (7 pages) | Cited 2 times

Online Publication Date: 24 April 2002

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A technique has been developed to separately obtain emission spectra from individual ion–molecule and electron–ion recombination reactions. This involves using a flowing afterglow to create the reaction producing the emissions of interest and pulse modulating a gas into the afterglow that reacts with only the ion species causing that reaction in the plasma. In this way, photon emissions have been detected where other interfering emissions from the ionization source and from other reaction processes, are more than an order of magnitude larger. The technique has been tested with an He+/Ar+ plasma to which OCS had been added. In this case, with pulsed modulation of H2 into the plasma, emissions can be isolated from Ar+ reactions and from the electron recombination of its ion products, as well as from similar reactions involving H3+ (generated from the Ar+ reaction with H2). The technique is such that the majority of the data acquisition time is devoted to collecting data where there is significant signal with little time being used in wavelength regions where there is no significant signal. In these scans, photon counting times are varied to give all signal peaks the same signal to noise ratio independent of intensity and thus the same statistical significance. This is a considerable improvement over standard spectral scanning approaches. Critical features of the technique are evaluated and the means of optimizing the scan are discussed. © 2002 American Institute of Physics.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.20.Fs Electron collisions
34.80.Lx Recombination, attachment, and positronium formation
52.80.Hc Glow; corona
82.30.Fi Ion-molecule, ion-ion, and charge-transfer reactions
82.30.Nr Association, addition, insertion, cluster formation
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
32.30.Jc Visible and ultraviolet spectra
back to top MICROSCOPY and IMAGING

Polarization-modulation near-field optical microscope for quantitative local dichroism mapping

L. Ramoino, M. Labardi, N. Maghelli, L. Pardi, M. Allegrini, and S. Patanè

Rev. Sci. Instrum. 73, 2051 (2002); http://dx.doi.org/10.1063/1.1470710 (6 pages) | Cited 18 times

Online Publication Date: 24 April 2002

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A couple of experimental techniques have been implemented to an aperture near-field scanning optical microscopy (NSOM) to obtain reliable measurement of sample dichroism on the local scale. First, a method to test NSOM tapered fiber probes toward polarization conservation into the near optical field is reported. The probes are characterized in terms of the in-plane polarization of the near field emerging from their aperture, by using a thin dichroic layer of chromophore molecules, structured along stretched polymeric chains, to probe such polarization when approached in the near-field region of the probe. Second, to assure that the light intensity coupled in the fiber is polarization independent, an active system operating in real time has been realized. Such combination of techniques allowed quantitative imaging of local dichroism degree and average orientation by means of dual-phase lock-in demodulation of the optical signal. Translation of the coupled light polarization state in the near field has been observed for one-half of the tested probes. For the others, the tip acts as a polarizer, and therefore showed it was not suitable for polarization modulation NSOM measurements. © 2002 American Institute of Physics.
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07.79.Fc Near-field scanning optical microscopes
78.20.Fm Birefringence

High-speed near-field scanning optical microscopy with a quartz crystal resonator

Yongho Seo and Wonho Jhe

Rev. Sci. Instrum. 73, 2057 (2002); http://dx.doi.org/10.1063/1.1470233 (3 pages) | Cited 7 times

Online Publication Date: 24 April 2002

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We demonstrate high-speed near-field scanning optical microscopy using a tapered fiber tip that is inserted in a perforated quartz-crystal resonator. With this high-frequency dithering probe, we have obtained near-field optical images at the scanning speed of 1.3 mm/s and it takes only 0.5 s to image the surface area of 100 μm2 for 64×64 pixels without any compromise of spatial lateral resolution. As an application, we have obtained sequential scanning images of the diffusing microspheres in water, which shows slow change of the sample configuration in the time scale of several minutes. © 2002 American Institute of Physics.
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07.79.Fc Near-field scanning optical microscopes
77.65.Fs Electromechanical resonance; quartz resonators
back to top CONDENSED MATTER; MATERIALS

A portable ultrahigh vacuum apparatus for the production and in situ characterization of clusters and cluster-assembled materials

E. Barborini, F. Siviero, S. Vinati, C. Lenardi, P. Piseri, and P. Milani

Rev. Sci. Instrum. 73, 2060 (2002); http://dx.doi.org/10.1063/1.1470226 (7 pages) | Cited 10 times

Online Publication Date: 24 April 2002

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We present and discuss the design and operation of a compact ultrahigh vacuum compatible apparatus for the production and deposition of supersonic cluster beams. The apparatus is equipped with a pulsed microplasma cluster source capable of providing supersonic beams of high stability and intensity. The cluster mass distribution can be analyzed by a two-stage time-of-flight mass spectrometer. The transportability and versatility of the apparatus make the system well suited to perform in situ studies on both gas phase clusters and cluster assembled materials using different characterization facilities. The performances of the system have been tested by scanning tunneling microscopy and photoemission spectroscopy experiments on cluster-assembled carbon films. © 2002 American Institute of Physics.
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81.15.Jj Ion and electron beam-assisted deposition; ion plating
68.55.A- Nucleation and growth
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
81.07.Bc Nanocrystalline materials

A facility for characterizing the dynamic mechanical behavior of thin membranes for microelectromechanical systems

J. D. Hall, N. E. Apperson, B. T. Crozier, C. Xu, R. F. Richards, D. F. Bahr, and C. D. Richards

Rev. Sci. Instrum. 73, 2067 (2002); http://dx.doi.org/10.1063/1.1470227 (6 pages) | Cited 13 times

Online Publication Date: 24 April 2002

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A bulge testing system capable of applying static and dynamic loads to thin film membranes is described. The bulge tester consists of a sealed cavity, filled with a fluid, bounded on the bottom by a circular stainless steel diaphragm and on the top by the thin film membrane of interest. An actuator is used to apply either a static or a periodic force to the stainless steel diaphragm. The force is transmitted through the water to the thin film membrane. This facility provides for both accelerated lifetime testing and simulated service environment testing. The thin film membranes tested are composite stacks consisting of thin films of silicon, glass, metallic electrodes, and lead-zirconate-titanate. Pressure and deflection of a membrane are acquired simultaneously during loading. An image capture system coupled with an interferometer provides the means to capture interferograms of deflected membranes during both static and dynamic testing conditions. Images are then postprocessed to construct deflection versus pressure relationships, which can be used to extract materials’ properties. Accelerated lifetime testing is performed by subjecting the thin film membranes to cyclic loading at strain levels 45%–90% of the static failure strains. In simulated service environment testing thin film membranes are subjected to cyclic loading over a range of frequencies. For a given applied force, as the resonant frequency is approached the dynamic behavior of the thin film structures vary significantly from that observed for static loading. At resonance the deflection of a thin film membrane is almost three times that of a statically deflected membrane subjected to the same applied force. © 2002 American Institute of Physics.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.70.Bt Mechanical testing, impact tests, static and dynamic loads
81.70.Fy Nondestructive testing: optical methods
07.10.Cm Micromechanical devices and systems
07.60.Ly Interferometers
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy

Optical fiber interferometer for measuring the d33 coefficient of piezoelectric thin films with compensation of substrate bending

J. R. Fernandes, F. A. de Sá, J. L. Santos, and E. Joanni

Rev. Sci. Instrum. 73, 2073 (2002); http://dx.doi.org/10.1063/1.1463713 (6 pages) | Cited 6 times

Online Publication Date: 24 April 2002

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An optical fiber interferometer for measuring the d33 coefficient of piezoelectric samples is described. Its configuration is based on the Mach–Zehnder interferometer, and a double incidence on the thin-film samples successfully suppresses the undesirable bending effect of the substrate. Detection of the small displacement is based on an active homodyne scheme. Results are reported for a bulk piezoelectric transducer (PZT) sample and a PZT thin-film incorporated in a microactuator. © 2002 American Institute of Physics.
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85.50.-n Dielectric, ferroelectric, and piezoelectric devices
07.60.Ly Interferometers
42.81.Pa Sensors, gyros
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Cylindrical mirror multipass Lissajous system for laser photoacoustic spectroscopy

Lu-yuan Hao, Shi Qiang, Guo-rong Wu, Li Qi, Dang Feng, Qing-shi Zhu, and Zhang Hong

Rev. Sci. Instrum. 73, 2079 (2002); http://dx.doi.org/10.1063/1.1464653 (7 pages) | Cited 6 times

Online Publication Date: 24 April 2002

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A simple optical multiple reflection system is developed with two cylindrical concave mirrors at an appropriate spacing. The two cylindrical mirrors have different focal lengths and their principal sections are orthogonal. The alternate focusing of the two cylindrical mirrors at different direction keep the reflecting spots small. The reflecting spots fall on Lissajous patterns on the cylindrical mirrors. The mathematics for this optical system is described and the calculated coordinates of beam spots are very close matches of the experimental observations. The cylindrical mirror optical system is easy to construct and align, with a suitable method for obtaining long optical paths and a large number of passes in small volumes. In a photoacoustic spectrometer the beam family enhance the effective power in the photoacoustic cell and thus the signal-to-noise ratio of photoacoustic signal. An experimental result for photoacoustic spectrum of HDSe gas is given. © 2002 American Institute of Physics.
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42.79.Bh Lenses, prisms and mirrors
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
43.58.-e Acoustical measurements and instrumentation
51.70.+f Optical and dielectric properties
82.80.Kq Energy-conversion spectro-analytical methods (e.g., photoacoustic, photothermal, and optogalvanic spectroscopic methods)

A new tool for measuring polar magneto-optical Kerr hysteresis curves at high fields and low temperatures

Wilhelmus J. Geerts, Brian Donehew, Vaughan Williams, and Thomas Schmiedel

Rev. Sci. Instrum. 73, 2086 (2002); http://dx.doi.org/10.1063/1.1468683 (5 pages) | Cited 1 time

Online Publication Date: 24 April 2002

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The design of a unique probe to measure the magneto-optical (MO) Kerr rotation and MO Kerr ellipticity of thin films and multilayers at high magnetic fields (0–25 T) and low temperatures (2–325 K) is described. The design of the probe is based on direct optics. Magnetic iron was used to screen the optical components from the stray field of the magnet. The equipment has sensitivity better than 0.25 mdegree at 632.8 nm and the residual background that results from the Faraday rotation in the optical components is smaller than 2 mdegree/T. The probe measures the polar MO hysteresis curve of samples with dimensions from 0.5–2 cm. Preliminary results on a 9 monolayer iron film and a single-crystalline FePt sample show the performance of this new characterization tool. This new MO magnetometer can be used in one of the resistive magnets of the National High Magnetic Field Laboratory in Tallahassee and is available for all internal and external users. © 2002 American Institute of Physics.
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07.55.Jg Magnetometers for susceptibility, magnetic moment, and magnetization measurements
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
78.66.Bz Metals and metallic alloys
78.20.Ls Magneto-optical effects
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Noncontact technique for determining viscosity from the shape relaxation of ultrasonically levitated and initially elongated drops

K. Ohsaka, A. Rednikov, S. S. Sadhal, and E. H. Trinh

Rev. Sci. Instrum. 73, 2091 (2002); http://dx.doi.org/10.1063/1.1470228 (6 pages) | Cited 5 times

Online Publication Date: 24 April 2002

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We present a technique that can determine the viscosity of highly viscous liquids, particularly, undercooled liquids that exist at temperatures below their freezing points. The technique involves levitation of a liquid drop using an ultrasonic standing wave, and elongation of the drop by rotating it beyond the point of bifurcation. The elongated drop is then allowed to be restored to its original shape by surface tension driven relaxation. The time-dependent shape parameters of the relaxing drop are related to the viscosity through a relaxation model. In addition, this technique can also determine the surface tension that has a known relationship with the angular velocity at the bifurcation point. The feasibility of the technique is demonstrated by performing the measurement using sucrose solutions as a model liquid drop. The obtained viscosity values show a good correlation with those determined by a falling ball method. © 2002 American Institute of Physics.
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83.85.Jn Viscosity measurements
47.80.-v Instrumentation and measurement methods in fluid dynamics
68.03.Cd Surface tension and related phenomena

In-line dielectric monitoring during extrusion of filled polymers

Anthony J. Bur, Steven C. Roth, and Michael McBrearty

Rev. Sci. Instrum. 73, 2097 (2002); http://dx.doi.org/10.1063/1.1470235 (6 pages) | Cited 10 times

Online Publication Date: 24 April 2002

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Real-time monitoring of the dielectric properties of polymer melts and filled polymer melts has been carried out during extrusion. The measurements are obtained using a dielectric cell that is placed directly in line with the extruder machine. The dielectric cell consists of interdigitating electrodes that are deposited on the inside of a ceramic ring that is electrically insulated and temperature controlled to the set point of extrusion. As the processed resin passes through the ring, its permittivity and conductivity are measured. The spatial sensitivity of the cell was determined experimentally and was biased to the resin flowing near the electrodes. Using the spatial sensitivity function, we examined the time profile of the transition from one composition to another during extrusion. We demonstrate the operation of the cell during the processing of polystyrene filled with aluminum oxide and calcium carbonate and of polyethylene-ethyl vinyl acetate copolymer filled with montmorillonite clay. © 2002 American Institute of Physics.
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81.10.Fq Growth from melts; zone melting and refining
81.05.Qk Reinforced polymers and polymer-based composites
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
77.22.Ch Permittivity (dielectric function)

Direct method for monitoring two-beam coupling in photorefractive materials

Jeffrey E. Hall and Daniel A. Higgins

Rev. Sci. Instrum. 73, 2103 (2002); http://dx.doi.org/10.1063/1.1472468 (5 pages)

Online Publication Date: 24 April 2002

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A method for directly monitoring two-beam coupling (2BC) in photorefractive materials is presented. This method allows accurate measurement of the gain and loss in the probe and pump beams, respectively, even in situations where substantial power is diffracted into higher order beams (i.e., for large grating spacings). Modulation of the pump beam at a frequency significantly greater than the grating decay rate, coupled with synchronous detection of the modulated probe beam signal, provides this information, automatically correcting for diffractive losses. The probe beam gain and pump beam loss are obtained without further correction. 2BC measurements are made on dye-doped photorefractive polymer-supported liquid crystal films to demonstrate the advantages of this method. The measurements are made for small grating spacings, in which little high-order diffraction is observed, and for large grating spacings for which there are several diffraction orders. © 2002 American Institute of Physics.
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42.70.Gi Light-sensitive materials
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
78.47.-p Spectroscopy of solid state dynamics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Adhesives for highly polished surfaces and low temperature: A simple test and results

Isaac F. Silvera, A. Abate, A. Chijioke, and A. Pashin

Rev. Sci. Instrum. 73, 2108 (2002); http://dx.doi.org/10.1063/1.1470237 (7 pages) | Cited 1 time

Online Publication Date: 24 April 2002

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A simple procedure for testing the bonding strength of adhesives to surfaces is presented. Tests are carried out on highly polished bonded glass slides for a number of adhesives so the adhesion strength can be characterized. Samples are also cycled to liquid nitrogen temperature to test the effect of thermal cycling on the adhesion strength. A few tests were carried out at liquid helium temperatures. Results are presented for a number of commercially available adhesives. © 2002 American Institute of Physics.
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81.70.Bt Mechanical testing, impact tests, static and dynamic loads
68.35.Np Adhesion
back to top CHEMISTRY

Tandem time-of-flight mass spectrometer (TOF-TOF) with a quadratic-field ion mirror

Anastassios E. Giannakopulos, Benjamin Thomas, Alex W. Colburn, David J. Reynolds, Emmanuel N. Raptakis, Alexander A. Makarov, and Peter J. Derrick

Rev. Sci. Instrum. 73, 2115 (2002); http://dx.doi.org/10.1063/1.1470229 (9 pages) | Cited 11 times

Online Publication Date: 24 April 2002

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A tandem time-of-flight (TOF-TOF) mass spectrometer comprised of two ion mirrors is described. The first ion mirror, which is a linear-field, single-stage mirror (MS1) with an intermediate collision cell, has been designed to provide the temporal focus necessary for the second, quadratic-field ion mirror (MS2) to function effectively. Due to the wide energy-range focusing capabilities of the quadratic field employed in the second ion mirror all the fragment ions can be collected in one spectrum without the need to step the reflecting working voltage of the MS2. The size of the active area of the microchannel plate detector used in the preliminary experiments was the limiting factor governing the collection efficiently of fragment ions. The use of the first ion mirror to provide temporal focusing of the precursor ion packet at the first focal point of the quadratic mirror used as the MS2 requires no alteration of the focusing conditions for different masses, in contrast to delayed extraction or postsource pulsed focusing. Precursor ions formed by matrix-assisted laser desorption/ionization were mass-selected with an ion gate located before the collision cell and the fragment ions were mass analyzed using the quadratic-field ion mirror. Experimental results demonstrating effective high-energy collision-induced dissociation of polymer and fullerene molecule-ions are presented. © 2002 American Institute of Physics.
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07.75.+h Mass spectrometers
68.43.Tj Photon stimulated desorption

In situ x-ray absorption fuel cell

Rameshkrishnan Viswanathan, Renxuan Liu, and Eugene S. Smotkin

Rev. Sci. Instrum. 73, 2124 (2002); http://dx.doi.org/10.1063/1.1472469 (4 pages) | Cited 9 times

Online Publication Date: 24 April 2002

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An in situ x-ray absorption spectroscopy cell was designed to study the structural and electronic properties of high performance polymer electrolyte fuel cell electrocatalysts. The cell was operated as a standard fuel cell and x-ray absorption data were collected simultaneously as the fuel cell operating conditions were varied. The cell was used to examine platinum–ruthenium alloy electrocatalysts incorporated in the anode of a fuel cell membrane and electrode assembly. In situ Pt LIII and Ru K edge x-ray absorption near-edge structure (XANES) data were collected at five selected current densities of the operating fuel cell. The XANES data show that under normal fuel cell operating conditions, the metallic nature of the Pt–Ru catalyst is retained. The cell design enabled an in situ fuel cell study at a synchrotron source in which no additional electrolytes were required. © 2002 American Institute of Physics.
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82.47.-a Applied electrochemistry
78.70.Dm X-ray absorption spectra
82.45.Jn Surface structure, reactivity and catalysis
07.85.Nc X-ray and γ-ray spectrometers
back to top BIOLOGY and MEDICINE

Using two-photon standing waves and patterned photobleaching to measure diffusion from nanometers to microns in biological systems

Sara K. Davis and Christopher J. Bardeen

Rev. Sci. Instrum. 73, 2128 (2002); http://dx.doi.org/10.1063/1.1464656 (8 pages) | Cited 5 times

Online Publication Date: 24 April 2002

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A method of measuring molecular diffusion rates in microscopic sample volumes is described. This method utilizes the standing wave interference created by colliding two counterpropagating laser beams at the focus of two opposing microscope objectives, creating a periodic light distribution in a volume on the order of 1 fl. By using a Pockels cell to vary the laser intensity with a time resolution of milliseconds, we show how this experimental geometry can be used to perform ultrahigh resolution fluorescence recovery after patterned photobleaching (FRAPP) experiments. A mathematical treatment of the experiment shows that the laser excitation profile has two characteristic length scales, the width of the focal spot and the period of the standing wave, which permits the simultaneous measurement of dynamics on two separate length scales. This feature may be used to determine whether the measured diffusion is anomalous. We present experimental results using a femtosecond Ti:sapphire laser to create a two-photon excitation profile with a fringe visibility on the order of 100. This standing wave is used to demonstrate FRAPP in both model dye/polymer systems and in more complex systems like living cells stained with a fluorescent dye. By combining the advantages of standing wave microscopy and two-photon fluorescence recovery after photobleaching, this technique permits the measurement of very short length motions in localized sample volumes, which should be useful in both biology and the study of diffusion in microscopically heterogeneous systems. © 2002 American Institute of Physics.
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87.64.mn Multiphoton
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
87.15.Vv Diffusion
42.62.Be Biological and medical applications
87.64.M- Optical microscopy
back to top GRAVITY; GEOPHYSICS; ASTRONOMY and ASTROPHYSICS

Development of a light source with an injection-locked Nd:YAG laser and a ring-mode cleaner for the TAMA 300 gravitational-wave detector

Shigeo Nagano, Mark A. Barton, Hideki Ishizuka, Kazuaki Kuroda, Sumihiro Matsumura, Osamu Miyakawa, Shinji Miyoki, Daisuke Tatsumi, Takayuki Tomaru, Takashi Uchiyama, Masaki Ando, Koji Arai, Keita Kawabe, Naoko Ohishi, Akiteru Takamori, et al.

Rev. Sci. Instrum. 73, 2136 (2002); http://dx.doi.org/10.1063/1.1470230 (7 pages) | Cited 9 times

Online Publication Date: 24 April 2002

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We have developed a light source suitable for laser interferometric gravitational-wave detectors. The developed light source has high power, TEM00 mode, linear polarization, high frequency stability, and low intensity noise. The light source with the quality is essential for attaining the goal sensitivity in the TAMA 300 and was found to be available for a observation run of a gravitational-wave detector. © 2002 American Institute of Physics.
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95.55.Ym Gravitational radiation detectors; mass spectrometers; and other instrumentation and techniques
07.60.Ly Interferometers
42.60.Fc Modulation, tuning, and mode locking
04.80.Nn Gravitational wave detectors and experiments
42.72.-g Optical sources and standards
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