RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Oct 2004

Volume 75, Issue 10, pp. 3091-4349

Page 1 of 2 Pages Return to All Sections Next Page
back to top
RSS Feeds
back to top MICROSCOPY AND IMAGING

Low-temperature field emission system for development of ultracoherent electron beams

B. Cho, T. Ogawa, T. Ichimura, T. Ichinokawa, T. Amakusa, and C. Oshima

Rev. Sci. Instrum. 75, 3091 (2004); http://dx.doi.org/10.1063/1.1790581 (6 pages) | Cited 5 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
Here, we present the design and test-operation performance of a low-temperature field emission (FE) system which can be employed to image and characterize the FE beam from low-temperature tips. Three radiation shields cooled by liquid helium and liquid nitrogen cryostats surround the FE tips and anodes completely. Once the FE system is cooled down to 5 K, experiments can run for more than 15 h without interruption. The design allows not only for the exchange of tips and anodes by load-lock equipment but also for the adjustment of tip–anode distance using a piezo-tube. Test runs in projection microscopy mode have presented clear diffraction-fringe patterns near the shadows of nano objects at temperatures from room temperature to 5.5 K, indicating that the system is well suited for the investigation of the coherence of electron beam from FE tip.
Show PACS
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
41.75.Fr Electron and positron beams
41.85.Ar Particle beam extraction, beam injection
back to top CONDENSED MATTER; MATERIALS

Fast and adjustable-resolution grazing-incidence x-ray liquid surface diffraction

Philippe Fontaine, Michel Goldmann, Michel Bordessoule, and Alain Jucha

Rev. Sci. Instrum. 75, 3097 (2004); http://dx.doi.org/10.1063/1.1790582 (10 pages) | Cited 8 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
We developed a configuration using a two-dimensional detector for grazing incidence x-ray diffraction on Langmuir monolayers and, more generally, for surface diffraction on two-dimensional powders. Compared to the classical setup using a linear detector combined with Soller slits, the acquisition time is reduced by an order of magnitude (from more than 1 h to a few minutes) using the same x-ray source (synchrotron bending magnet) with a comparable signal to noise ratio. Moreover, experimental resolution can be adjusted by varying a vertical slit (horizontal gap) and, for small values of the gap, better resolution can be achieved compared to the one obtained with the Soller slits and linear detector.
Show PACS
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
07.85.Jy Diffractometers
61.05.cp X-ray diffraction
back to top CHEMISTRY

Measurements of picosecond lifetimes by time correlated single photon counting method: The effect of the refraction index of the solvent on the instrument response function

Teresa Wróżowa, Barbara Ciesielska, Dariusz Komar, Jerzy Karolczak, Andrzej Maciejewski, and Jacek Kubicki

Rev. Sci. Instrum. 75, 3107 (2004); http://dx.doi.org/10.1063/1.1790583 (15 pages) | Cited 13 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
The article concerns the possibility of precise picosecond lifetime measurements by the method of the time correlated single photon counting (TCSPC). The lifetimes (τ) of S2 fluorescence of xanthione measured in different solvents have shown that it is possible to obtain τ as short as a few picoseconds. The values of τ varying from ∼ 5 to  ∼ 38 ps in solvents whose refraction indices range from 1.34 to 1.50 have been proposed as picosecond standards in lifetime measurements. However, in order to obtain reliable results some conditions must be met: the effect of the absorbing and emitting impurities must be eliminated, the instrument response function (IRF) must be very stable and correctly determined, and because of a much lower time resolution of the TCSPC method relative to that of the upconversion method, the procedure of measurements and numerical analysis of results proposed in our work should be applied. In the study reported the effect of impurities was eliminated by applying high performance liquid chromatography to choose the excitation and emission wavelength for which the emission of impurities is negligible for fluorescence decay measurements of the sample (S) and reference (R). It has been shown that the IRF in TCSPC depends on the refraction index of the solvent used. In order to avoid the systematic errors related to different IRF for S and R, the calculations of fluorescence lifetimes should be performed for S and R in solvents of the possibly most similar refraction indices. The effect of the solvents difference in the refraction indices on the shape of IRF has been shown and then on the fluorescence lifetimes below 20 ps. The proposed procedure of determination of single picosecond lifetimes with the use of TCSPC is particularly suitable when it is necessary to use a very low concentration ( ⩽ 10−5 M) of the compound studied in order to avoid dimers and oligomers formation (in the upconversion method concentration >10−4 M is generally used). A very good statistics of the TCSPC method—much better than in the other time-resolved methods—together with the use of the procedure of measurements—the procedure of numerical analysis and procedure of elimination of emission of impurities proposed in our article—permit elimination of the systematic errors (usually ±3 ps) in the lifetimes determined for monoexponential decays and obtaining a highly reliable description of the fluorescence decay kinetics also when the fluorescence decay is nonexponential.
Show PACS
07.60.Dq Photometers, radiometers, and colorimeters
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
82.80.Bg Chromatography
back to top CONDENSED MATTER; MATERIALS

A system of Kerr effect spectroscopy for light absorbing liquids

Kazuyoshi Horii and Keiji Sakai

Rev. Sci. Instrum. 75, 3122 (2004); http://dx.doi.org/10.1063/1.1790553 (5 pages) | Cited 3 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
We developed experimental system of the optical Kerr effect spectroscopy for the light absorbing liquids. To avoid the problems due to the light absorption, such as the thermal lens effect, our new system used a gated rectangular light pulse with the alternative polarization modulation as the pump light. The experimental results of the transient behavior of the signal showed that our system could clearly distinguish the optical Kerr effect from the thermal lens effect. Careful monitoring of the signal enables us to suppress the temperature increase within the experimental latitude. We examined the previous results that the optical anisotropy of the isotropic liquid crystals induced by the external field is enhanced dramatically compared with the pure liquid crystals by doping a small amount of the dye from the viewpoint of relaxation dynamics. The information on the dynamic molecular orientation relaxation obtained by our spectroscopy would help us understand a microscopic interaction among liquid crystals and dye molecules, especially in the vicinity of the transition temperature. The system would be useful widely for the measurement of the nonlinear optical properties in the materials, which show strong light absorption or scattering.
Show PACS
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.25.Bs Wave propagation, transmission and absorption
42.65.-k Nonlinear optics
42.25.Fx Diffraction and scattering
42.70.Df Liquid crystals
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

A new experimental design for noncontact giant magnetoresistance measurements using the magnetorefractive effect

M. Vopsaroiu, J. A. D. Matthew, and S. M. Thompson

Rev. Sci. Instrum. 75, 3127 (2004); http://dx.doi.org/10.1063/1.1790554 (4 pages) | Cited 5 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
Electrical magnetoresistance measurements of spin dependent materials or devices are very difficult without surface damaging or sample contamination, especially for thin-film giant magnetoresistance (GMR) multilayers. Moreover, the in situ determination of the GMR profile is almost impossible using electrical measurements. We propose a novel experimental design that allows the convenient measurement of magnetoresistance profiles using a noncontact method based on the magnetorefractive effect. This technique is applicable to metallic samples or devices showing magnetotransport properties and is also suitable for in situ measurements. The experiment involves infrared (IR) reflectivity measurements as a function of the applied magnetic field. By introducing IR optical fibers, the experimental setup has been substantially simplified while the need for costly optical components and time consuming alignments has been eliminated. Theoretical simulations of this experiment are also presented prior to the introduction of the proposed design.
Show PACS
75.50.Cc Other ferromagnetic metals and alloys
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.De Giant magnetoresistance
78.20.Ls Magneto-optical effects
78.66.Bz Metals and metallic alloys
78.30.Er Solid metals and alloys
75.40.Mg Numerical simulation studies
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Characterization of CsI photocathodes at grazing incidence for use in a unit quantum efficiency x-ray streak camera

D. P. Lowney, P. A. Heimann, H. A. Padmore, E. M. Gullikson, A. G. MacPhee, and R. W. Falcone

Rev. Sci. Instrum. 75, 3131 (2004); http://dx.doi.org/10.1063/1.1790558 (7 pages) | Cited 5 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
The performance of CsI photocathodes has been characterized for use with grazing incidence soft x rays. The total electron yield and pulsed quantum efficiency of a CsI photocathode has been measured in a reflection geometry as a function of photon energy (100 eV to 1 keV), angle of incidence, and the electric field between the anode and photocathode. The total electron yield and pulsed quantum efficiency increase as the x-ray penetration depth approaches the secondary electron escape depth. Unit quantum efficiency in a grazing incidence geometry is demonstrated. A weak electric-field dependence is observed for the total yield measurements; while no significant dependence is found for the pulsed quantum efficiency. The effect of the pulse height distribution on the detective quantum efficiency is discussed. Theoretical predictions agree accurately with experiment.
Show PACS
85.60.Ha Photomultipliers; phototubes and photocathodes
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
41.50.+h X-ray beams and x-ray optics
07.68.+m Photography, photographic instruments; xerography
06.60.Jn High-speed techniques (microsecond to femtosecond)
79.20.Hx Electron impact: secondary emission
back to top PARTICLE SOURCES, OPTICS AND ACCELERATION; PARTICLE DETECTORS

A new plasma potential measurement instrument for plasma ion sources

O. Tarvainen, P. Suominen, and H. Koivisto

Rev. Sci. Instrum. 75, 3138 (2004); http://dx.doi.org/10.1063/1.1790559 (8 pages) | Cited 13 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A very efficient and fast instrument to measure the plasma potential of ion sources has been developed at the Department of Physics, University of Jyväskylä (JYFL). The operating principle of this novel instrument is to apply a decelerating voltage into a mesh located in the beamline of the ion source. The plasma potential is determined by measuring the current at the grounded electrode situated behind the mesh as a function of the voltage. In this article, we will introduce the instrument and the first results. In the experiments, the instrument was connected to the beamline of the JYFL 6.4 GHz electron cyclotron resonance ion source. The plasma potential was measured with different source conditions and it was observed to vary between 30–65 V. The plasma potential tended to increase as the microwave power, or the gas feed rate, was increased. These results are consistent with earlier observations and estimations. It was also noticed that the value of the plasma potential changed when the negative voltage applied to the biased disk at the injection of the ion source was varied. Complementary to optical plasma diagnostics, such an instrument can be used as a very efficient tool to get a precise relationship between plasma conditions and extracted beams.
Show PACS
52.70.Gw Radio-frequency and microwave measurements
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
07.77.Ka Charged-particle beam sources and detectors
29.25.Ni Ion sources: positive and negative
52.59.-f Intense particle beams and radiation sources
52.75.-d Plasma devices
41.75.-i Charged-particle beams
back to top MICROSCOPY AND IMAGING

Contrast and resolution in direct Fresnel diffraction phase-contrast imaging with partially coherent x-ray source

Shensheng Han, Hong Yu, Jing Cheng, Chen Gao, and Zhenlin Luo

Rev. Sci. Instrum. 75, 3146 (2004); http://dx.doi.org/10.1063/1.1790560 (6 pages) | Cited 4 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A general treatment of x-ray image formation by direct Fresnel diffraction with partially coherent hard x rays is presented. Contrast and resolution are the criteria used to specify the visibility of an image, which depend primarily on the spatial coherence of the illumination and the distance from object to the image, with chromatic coherence of lesser importance. The dependence of the quality of phase-contrast images on the parameters of in-line imaging configuration is described quantitatively. The influence of spatial coherence of hard x-ray source on the imaging quality is also discussed based on the partially coherent direct Fresnel diffraction phase-contrast imaging theory. Experimental results are also presented for phase-contrast x-ray images with partially coherent hard x rays.
Show PACS
07.85.-m X- and γ-ray instruments
07.05.Pj Image processing
back to top CHEMISTRY

High-pressure nuclear magnetic resonance probe designed for a narrow bore magnet system

Achim Zahl, Peter Igel, Manfred Weller, and Rudi van Eldik

Rev. Sci. Instrum. 75, 3152 (2004); http://dx.doi.org/10.1063/1.1786357 (6 pages) | Cited 6 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
The development of a high-pressure nuclear magnetic resonance (NMR) probe designed for a 400 MHz narrow bore NMR spectrometer is reported. As for the earlier constructed system for wide bore magnets, the electrical leads of the radio frequency (rf) circuit, the tubes for the thermostating and high-pressure transmitting fluids, as well as the connections for the temperature control unit are all fitted through the bottom of the high-pressure vessel. The sample can easily be removed and rapidly exchanged through a top plug in the vessel. There is no need to modify the magnet in order to perform the high-pressure experiments. In comparison to the already published wide bore design, the spectral resolution could be improved to be better than 6×10−9 by selecting a different titanium alloy and a more symmetrical design. The high-pressure vessel and the rf circuit are placed in an aluminum jacket which has the same outer dimensions as a commercial narrow bore probe and can be fitted into the magnet in the same way.
Show PACS
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
back to top CONDENSED MATTER; MATERIALS

Instrumentation for cryogenic microwave cavity resonance measurements

C. C. Tsai, J. R. Feller, Bimal K. Sarma, and J. B. Ketterson

Rev. Sci. Instrum. 75, 3158 (2004); http://dx.doi.org/10.1063/1.1781387 (6 pages)

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
We describe instrumentation and measurement procedures for performing microwave measurements on small metallic samples at dilution refrigerator temperatures using the microwave cavity perturbation technique. The quality factor Q of the lead-plated cavity was of order of 105 at temperatures below the superconducting transition temperature of lead. Microwaves were coupled into and out of the resonator through two room-temperature positionable semirigid coaxial lines, each terminated in a small-loop antenna. We describe in detail the arrangement of the apparatus used to tune to, and lock onto, a cavity resonance and the strategy used to categorize various resonance modes. One of the main features of this microwave spectrometer is the application of the FM detection method to measure changes in both the frequency and the quality factor of the sample-loaded cavity. The procedures for converting these quantities to the real and imaginary components of the surface impedance are described. As an application of the methodology used, we present some results of measurements on the superconducting response of a heavy fermion superconductor, UBe13, which can be fitted with the Mattis–Bardeen theory.
Show PACS
74.70.Tx Heavy-fermion superconductors
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
74.25.N- Response to electromagnetic fields
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
back to top GENERAL INSTRUMENTS

Industrial application of ultrasound based in-line rheometry: From stationary to pulsating pipe flow of chocolate suspension in precrystallization process

Boris Ouriev, Erich Windhab, Peter Braun, and Beat Birkhofer

Rev. Sci. Instrum. 75, 3164 (2004); http://dx.doi.org/10.1063/1.1790585 (5 pages) | Cited 2 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
In-line visualization and on-line characterization of nontransparent fluids becomes an important subject for process development in food and nonfood industries. In our work, a noninvasive Doppler ultrasound-based technique is introduced. Such a technique is applied for investigation of nonstationary flow in the chocolate precrystallization process. Unstable flow conditions were induced by abrupt flow interruption and were followed up by strong flow pulsations in the piping system. While relying on available process information, such as absolute pressures and temperatures, no analyses of flow conditions or characterization of suspension properties could possibly be done. It is obvious that chocolate flow properties are sensitive to flow boundary conditions. Therefore, it becomes essential to perform reliable structure state monitoring and particularly in application to nonstationary flow processes. Such flow instabilities in chocolate processing can often lead to failed product quality with interruption of the mainstream production. As will be discussed, a combination of flow velocity profiles, on-line fit into flow profiles, and pressure difference measurement are sufficient for reliable analyses of fluid properties and flow boundary conditions as well as monitoring of the flow state. Analyses of the flow state and flow properties of chocolate suspension are based on on-line measurement of one-dimensional velocity profiles across the flow channel and their on-line characterization with the power-law model. Conclusions about flow boundary conditions were drawn from a calculated velocity standard mean deviation, the parameters of power-law fit into velocity profiles, and volumetric flow rate information.
Show PACS
47.80.-v Instrumentation and measurement methods in fluid dynamics
47.60.-i Flow phenomena in quasi-one-dimensional systems
83.80.Hj Suspensions, dispersions, pastes, slurries, colloids
43.35.Yb Ultrasonic instrumentation and measurement techniques
47.27.nb Boundary layer turbulence
83.80.Ya Processed food
back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Cryogenic amplifier for ∼ 1 MHz with a high input impedance using a commercial pseudomorphic high electron mobility transistor

A. M. Robinson and V. I. Talyanskii

Rev. Sci. Instrum. 75, 3169 (2004); http://dx.doi.org/10.1063/1.1790586 (8 pages) | Cited 6 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A cryogenic amplifier for ∼ 100 kHz to a few MHz is presented which uses a commercially available pseudomorphic GaAs/InGaAs high electron mobility transistor and dissipates less than 0.5 mW in the cryogenic stage. The input-referred voltage noise and current noise of the amplifier at approximately 2 MHz are measured to be approximately 0.7 nV Hz−1/2 and 25 fA Hz−1/2, respectively. A superconducting resonant circuit can be used to provide a high input impedance over a narrow bandwidth, or a low input impedance can be used to yield a large bandwidth. Although suitable for many applications, the amplifier has been developed for measurements of current noise from a high-impedance source, and its long-term stability is such that by averaging over 30 min, it could be used to detect approximately 0.6 fA Hz−1/2.
Show PACS
85.30.Tv Field effect devices
84.30.Le Amplifiers
back to top NUCLEAR PHYSICS, FUSION AND PLASMAS

Comparison of different methods of electron cyclotron emission-correlation radiometry for the measurement of temperature fluctuations in the plasma core

Christopher Watts, H. J. Hartfuss, and M. Häse

Rev. Sci. Instrum. 75, 3177 (2004); http://dx.doi.org/10.1063/1.1790567 (8 pages) | Cited 8 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
ECE correlation radiometry is a technique for measuring high frequency electron temperature fluctuations in the plasma core of fusion relevant devices. Two correlation methods, based on different physical principles, have been developed at W7-AS and TEXT-U. Depending on the required application, the two techniques can offer complementary advantages. At W7-AS a comparison of both techniques has been carried out. In all measurements both techniques yield identical results to within measurement error. The advantages of each method are discussed.
Show PACS
52.70.Gw Radio-frequency and microwave measurements
52.25.Gj Fluctuation and chaos phenomena
52.55.Jd Magnetic mirrors, gas dynamic traps
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
back to top GENERAL INSTRUMENTS

Development of thrust stand for low impulse measurement from microthrusters

H. Koizumi, K. Komurasaki, and Y. Arakawa

Rev. Sci. Instrum. 75, 3185 (2004); http://dx.doi.org/10.1063/1.1790568 (6 pages) | Cited 12 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A thrust stand has been developed to accurately measure thrust produced by two types of microthrusters—a liquid propellant pulsed plasma thruster (LP-PPT) and a diode laser ablation microthruster. The impulse of LP-PPT ranged from 20 to 80 μNs. The diode laser microthruster, which is a new type of microthruster, produces much lower impulse range of 1–10 μNs for about 1 s. The mechanical noise induced from the background vibrations becomes a crucial problem for precise estimate of thrust particularly in low impulse measurements. A data analysis method to reduce the effect of mechanical noise is proposed by introducing an additional term in a fitting function. It was verified that the analysis method used in our experimental conditions reduced variance caused by noise down to one-third that of a normal fitting method. The accuracy of the thrust stand is 2.1 μNs in the case of the LP-PPT and 0.7 μNs in the case of the diode laser microthruster.
Show PACS
07.10.Pz Instruments for strain, force, and torque
52.38.Kd Laser-plasma acceleration of electrons and ions
back to top MICROSCOPY AND IMAGING

Microtomography and improved resolution in cathodoluminescence microscopy using confocal mirror optics

D. S. H. Chan, Y. Y. Liu, J. C. H. Phang, E. Rau, R. Sennov, and A. V. Gostev

Rev. Sci. Instrum. 75, 3191 (2004); http://dx.doi.org/10.1063/1.1790551 (9 pages) | Cited 1 time

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
Cathodoluminescence in scanning electron microscopy observed using an ellipsoidal confocal light collector system can offer improved resolution and an implementation of microtomography. With this signal collection system, the resolution limit is no longer determined by the beam and specimen properties but by the system optics. This possibility is demonstrated by the modeling of light transport in cathodoluminescent materials and in the ellipsoidal confocal system which collects the light emission. The conditions for the high-resolution three-dimensional visualization of microstructure within the generation volume of cathodoluminescence emission is described.
Show PACS
42.79.Bh Lenses, prisms and mirrors
78.60.Hk Cathodoluminescence, ionoluminescence
07.60.Pb Conventional optical microscopes
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
85.60.Gz Photodetectors (including infrared and CCD detectors)
back to top CHEMISTRY

A visual acoustic high-pressure cell for the study of critical behavior of nonsimple mixtures

A. Aguiar-Ricardo, M. Temtem, T. Casimiro, and N. Ribeiro

Rev. Sci. Instrum. 75, 3200 (2004); http://dx.doi.org/10.1063/1.1790552 (3 pages) | Cited 4 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A visual acoustic high-pressure cell was constructed for the determination of critical data of multicomponent mixtures. The cell was specially designed to include two piezoelectric transducers and two sapphire windows that make this cell well suited to investigate the critical behavior of mixtures, simultaneously using the acoustic technique and the direct visual inspection of the critical opalescence. Critical data obtained on the binary mixtures of CO2+CHF3 were used for comparison with values given in literature using the traditional methods. The acoustic results are in agreement with those obtained by the conventional methods, within the combined experimental errors. Comparison of visual and acoustic data enabled the evaluation of the applicability of the acoustic technique to study the critical behavior of multicomponent mixtures.
Show PACS
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
43.38.Fx Piezoelectric and ferroelectric transducers
05.70.Jk Critical point phenomena
43.58.-e Acoustical measurements and instrumentation
back to top THERMOMETRY; THERMAL DIFFUSIVITY; ACOUSTIC; PHOTOTHERMAL AND PHOTOACOUSTIC

Application of the acousto-optic effect to pressure measurements in ultrasound fields in water using a laser vibrometer

J. M. Buick, J. A. Cosgrove, P.-A. Douissard, C. A. Greated, and B. Gilabert

Rev. Sci. Instrum. 75, 3203 (2004); http://dx.doi.org/10.1063/1.1790556 (5 pages) | Cited 2 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A non-intrusive measuring technique, applied to sensing and measuring acoustic waves at ultrasonic frequencies is considered. The method is optically based and so does not interfere with the ultrasound field. The measurement procedure relies on the acousto-optic effect, that is the change in refractive index which occurs with changing pressure in the ultrasound field. This change in refractive index is detected through the change in the path length of a laser beam propagating through the region of interest. Typically these changes are small corresponding to a physical change of the order of 10−6 m. Fourier analysis is used to separate the component of the signal corresponding to the pressure variation from background noise and vibrations which can be dominant. Application of the technique is illustrated for an underwater ultrasound transducer. Measurements are made using the optical technique and compared to measurements taken with a hydrophone. The effectiveness of the optical measuring technique is discussed. It is shown that the laser vibrometer produces a good estimation of the mean beam pressure provided an estimation of the beam width is available, a restriction which is often satisfied; and the acoustic field can be assumed to be approximately constant across the beam.
Show PACS
07.64.+z Acoustic instruments and equipment
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.30.Yj Transducers and transducer arrays for underwater sound; transducer calibration
43.58.Fm Sound level meters, level recorders, sound pressure, particle velocity, and sound intensity measurements, meters, and controllers
43.35.Yb Ultrasonic instrumentation and measurement techniques
43.38.Pf Hydroacoustic and hydraulic transducers
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Applications of a single-longitudinal-mode alexandrite laser for diagnostics of parameters of combustion interest

Z. S. Li, M. Afzelius, J. Zetterberg, and M. Aldén

Rev. Sci. Instrum. 75, 3208 (2004); http://dx.doi.org/10.1063/1.1790557 (8 pages) | Cited 12 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
We report on the applications of a single-longitudinal-mode (SLM) pulsed alexandrite laser system for diagnostics of parameters of flow/combustion interest. The laser system is characterized by its narrow linewidth, high peak power, and broad tunablity. The absolute frequency of the laser output was monitored by a wavelength diagnostic system, which included a high-resolution confocal etalon and a molecular iodine laser-induced fluorescence (LIF) detection system. Different nonlinear frequency conversion schemes were used to cover a large frequency range from the infrared to the deep UV. The versatility of the laser system for flow/combustion diagnostics is demonstrated in three applications, namely filtered Rayleigh scattering, high-resolution Doppler-free two-photon LIF of CO, and infrared LIF and polarization spectroscopy of CO2. The potential impacts of using this SLM laser system in laser flow/combustion diagnostic applications are discussed.
Show PACS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
47.80.-v Instrumentation and measurement methods in fluid dynamics
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.62.Fi Laser spectroscopy
42.55.Rz Doped-insulator lasers and other solid state lasers
82.33.Vx Reactions in flames, combustion, and explosions

Versatile fiber-coupled system for simultaneous photon correlation spectroscopy and Fabry–Perot interferometry

R. B. Bogoslovov, D. P. Shelton, J. C. Selser, G. Piet, and S. Peng

Rev. Sci. Instrum. 75, 3216 (2004); http://dx.doi.org/10.1063/1.1790561 (8 pages) | Cited 2 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
We demonstrate an experimental setup utilizing fiber-optic detection and coupling of scattered light into existing photon correlation spectroscopy (PCS) and Fabry–Perot (F–P) interferometry systems. The performance of the fiber coupled F–P as a high-resolution interferometer is considered in detail. Several practical issues and limitations are discussed, including the selection of optic and fiber-optic components, collimation, effects of the fiber mode structure and core diameter, and alignment issues. A series of test measurements on standard systems with well known properties shows that the proposed fiber-optic design meets the performance expectations for both PCS and F–P instruments and presents an attractive alternative to the classical pinhole design.
Show PACS
07.60.Ly Interferometers
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
42.81.Bm Fabrication, cladding, and splicing
42.79.Ag Apertures, collimators
06.20.F- Units and standards
42.81.Wg Other fiber-optical devices
back to top PARTICLE SOURCES, OPTICS AND ACCELERATION; PARTICLE DETECTORS

An atom trap system for practical 81Kr dating

X. Du, K. Bailey, Z.-T. Lu, P. Mueller, T. P. O’Connor, and L. Young

Rev. Sci. Instrum. 75, 3224 (2004); http://dx.doi.org/10.1063/1.1790562 (9 pages) | Cited 4 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
81Kr (t1/2 = 2.3×105 yr, 81Kr/Kr ∼ 6×10−13) is a long-lived cosmogenic isotope, which is ideal for dating old groundwater and ice in the age range of 50,000 years to 1 million years. Here, we describe the apparatus and performance of an atom-counting system for practical 81Kr dating. This system is based upon the atom trap trace analysis method that was first demonstrated in 1999. Since then, significant improvements have been made to increase the system efficiency and to reduce the required krypton sample size. For a modern krypton gas sample of 100 μl STP, which contains 1.2×106 81Kr atoms, the system can accumulate approximately 240 81Kr counts in 20 h, thereby reaching a counting efficiency of 2×10−4. Detailed studies have been conducted to characterize the performance of this system. This system has been calibrated with a low-level counting method and has been used for 81Kr dating of ancient groundwater from the Nubian Aquifer (Egypt). It can also be used to measure the isotopic abundance of a fission-produced isotope 85Kr (t1/2 = 10.76 year,85Kr/Kr ∼ 2×10−11).
Show PACS
29.25.Rm Sources of radioactive nuclei
06.20.F- Units and standards
32.70.Cs Oscillator strengths, lifetimes, transition moments
32.10.Bi Atomic masses, mass spectra, abundances, and isotopes
37.10.De Atom cooling methods
37.10.Gh Atom traps and guides
37.10.Vz Mechanical effects of light on atoms, molecules, and ions
back to top CONDENSED MATTER; MATERIALS

Large-aperture variable-volume view cell for the determination of phase-equilibria in high pressure systems and supercritical fluids

Peter Licence, Martin P. Dellar, Richard G. M. Wilson, Peter A. Fields, David Litchfield, Helen M. Woods, Martyn Poliakoff, and Steven M. Howdle

Rev. Sci. Instrum. 75, 3233 (2004); http://dx.doi.org/10.1063/1.1790563 (4 pages) | Cited 22 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A high-pressure, variable-volume view cell incorporating a custom engineered, optically transparent sapphire piston is described. The view cell has an unbroken field of vision that enables the entire sample volume to be observed at all times. When lit from the rear of the cell, a near perfect view of any physical transition or change in state is available to the experimenter. The system has been shown to be particularly suitable for the determination of phase equilibria and cloud point measurements in supercritical fluid systems and has been rated for experiments up to 400 bar, 200 °C.
Show PACS
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
64.70.-p Specific phase transitions
back to top CHEMISTRY

Optical fiber gas sensor based on thermal lens spectroscopy

Atsushi Yarai and Takuji Nakanishi

Rev. Sci. Instrum. 75, 3237 (2004); http://dx.doi.org/10.1063/1.1791338 (5 pages) | Cited 2 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
This article describes how to design an optical fiber gas sensor based on a thermal lens (TL) spectroscopy instrument composed of spherical lensed fibers. This sensor features a detection head composed of two spherical lensed fibers assembled across from each other. The distance between the two fibers is just under 100 μm, with the gas in between. In other words, the optical absorption path length for our gas sensor is extremely short compared with that for other optical spectroscopic techniques (e.g., 10–20 mm ∼ 1–2 m). In addition, our gas sensor is extremely simple, small (e.g., 20 mm in length), adjustment-free and robust. These points are extremely important for actual use in the field. The measurement principle and theoretical analysis of the design are first described. Acetylene (12C2H2) gas is used as a sample gas to evaluate the sensitivity of our sensor. The limit of detection was estimated to be approximately 5200 Pa in our experimental condition. In the conclusion, the capability of our technique is discussed, and a technique for enhancing the sensitivity in our TL technique is proposed.
Show PACS
07.60.Vg Fiber-optic instruments
42.81.Pa Sensors, gyros
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.25.Bs Wave propagation, transmission and absorption
07.60.-j Optical instruments and equipment

An in situ cell for characterization of solids by soft x-ray absorption

Ian J. Drake, Teris C. N. Liu, Mary Gilles, Tolek Tyliszczak, A. L. David Kilcoyne, David K. Shuh, Richard A. Mathies, and Alexis T. Bell

Rev. Sci. Instrum. 75, 3242 (2004); http://dx.doi.org/10.1063/1.1791320 (6 pages) | Cited 18 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A cell has been designed and fabricated for in situ characterization of catalysts and environmental materials using soft x-ray absorption spectroscopy and spectromicroscopy at photon energies above 250 eV. “Lab-on-a-chip” technologies were used to fabricate the cell on a glass wafer. The sample compartment is 1.0 mm in diameter and has a gas path length of 0.8 mm to minimize x-ray absorption in the gas phase. The sample compartment can be heated to 533 K by an Al resistive heater and gas flows up to 5.0 cm3 min−1 can be supplied to the sample compartment through microchannels. The performance of the cell was tested by acquiring Cu L3-edge x-ray appearance near-edge structure (XANES) data during the reduction and oxidation of a silica-supported Cu catalyst using the beam line 11.0.2 scanning transmission x-ray microscope (STXM) at the Advanced Light Source of Lawrence Berkeley National Laboratory (Berkeley, CA). Two-dimensional images of individual catalyst particles were recorded at photon energies between 926 and 937 eV, the energy range in which the Cu(II) and Cu(I) L3 absorption edges are observed. Oxidation state specific images of the catalyst clearly show the disappearance of Cu(II) species during the exposure of the oxidized sample to 4% CO in He while increasing the temperature from 308 to 473 K. Reoxidation restores the intensity of the image associated with Cu(II). Cu L3-edge XANES spectra obtained from stacks of STXM images show that with increasing temperature the Cu(II) peak intensity decreases as the Cu(I) peak intensity increases.
Show PACS
07.85.Nc X-ray and γ-ray spectrometers
78.70.Dm X-ray absorption spectra
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.-b Specific chemical reactions; reaction mechanisms
81.65.Mq Oxidation
07.85.Tt X-ray microscopes
81.40.Gh Other heat and thermomechanical treatments
85.40.Hp Lithography, masks and pattern transfer
back to top MICROSCOPY AND IMAGING

Fabrication of super-sharp nanowire atomic force microscope probes using a field emission induced growth technique

A. B. H. Tay and J. T. L. Thong

Rev. Sci. Instrum. 75, 3248 (2004); http://dx.doi.org/10.1063/1.1791321 (8 pages) | Cited 15 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
A relatively simple and consistent technique based on field emission induced growth has been developed to grow a single metallic nanowire on an atomic force microscope (AFM) tip. A clamping setup with two micromanipulators ensures that the fabrication of a vertically aligned nanowire probe, which is sharp, robust, and with high aspect ratio, can be achieved on different types of AFM cantilevers with different force constants. The controlled growth technique has been used to produce tungsten nanowire AFM probes with great consistency and high reproducibility. The tungsten nanowires were grown to lengths between 100 nm to 1.5 μm with radius of curvature at the tip end typically between 1–2 nm. Experiments using the fabricated tungsten nanowire AFM probe demonstrate its ability to produce high-resolution AFM images and improved profiling of structures with steep sidewalls due to its very sharp tip and high aspect ratio. The technique can be extended to fabricating other types of metallic nanowire AFM probes or even composite nanowire AFM probes by using different precursor gases. Experiments have been successful in fabricating cobalt nanowire AFM probes which are able to produce good high-resolution AFM images as well.
Show PACS
81.07.Bc Nanocrystalline materials
61.46.-w Structure of nanoscale materials
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.37.Ps Atomic force microscopy (AFM)
79.70.+q Field emission, ionization, evaporation, and desorption
06.60.Sx Positioning and alignment; manipulating, remote handling
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
back to top CONDENSED MATTER; MATERIALS

Polarized neutron reflectometry of a patterned magnetic film with a 3He analyzer and a position-sensitive detector

W. C. Chen, T. R. Gentile, K. V. O’Donovan, J. A. Borchers, and C. F. Majkrzak

Rev. Sci. Instrum. 75, 3256 (2004); http://dx.doi.org/10.1063/1.1791312 (8 pages) | Cited 8 times

Online Publication Date: 20 September 2004

Full Text: | Download PDF

Show Abstract
We have employed a polarized 3He spin filter in conjunction with a position-sensitive detector (PSD) to perform efficient polarization analysis of neutron diffuse reflectivity. This work was carried out on the NG-1 polarized neutron reflectometer at the National Institute of Standards and Technology Center for Neutron Research. We measured the specular and diffuse reflectivity of a patterned magnetic array that has periodic square holes in a Co film. Analysis of the data yielded spin-analyzed two-dimensional Qx−Qz reciprocal space maps for the sample in magnetized and demagnetized states. We compared the measurements obtained with a 3He analyzer and a PSD with those obtained using a conventional supermirror analyzer and a 3He proportional counter. The results are in good agreement. For this experiment, 3He gas was polarized by the spin-exchange optical pumping method and stored in a uniform magnetic field provided by a shielded solenoid. Improved optical pumping using a spectrally narrowed diode laser array yielded an initial 3He polarization of 70% in a 3He cell volume of 280 cm3.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.50.Cc Other ferromagnetic metals and alloys
Page 1 of 2 Pages Return to All Sections Next Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close