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Top 20 Most Read Articles
January 2010
The 20 articles with the most full-text downloads during the month, in descending order.
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A portable high-field pulsed-magnet system for single-crystal x-ray scattering studies Rev. Sci. Instrum. 80, 113902 (2009); http://dx.doi.org/10.1063/1.3251273 (5 pages) Online Publication Date: 6 November 2009
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We present a portable pulsed-magnet system for x-ray studies of materials in high magnetic fields (up to 30 T). The apparatus consists of a split-pair of minicoils cooled on a closed-cycle cryostat, which is used for x-ray diffraction studies with applied field normal to the scattering plane. A second independent closed-cycle cryostat is used for cooling the sample to near liquid helium temperatures. Pulsed magnetic fields ( ∼ 1 ms in total duration) are generated by discharging a configurable capacitor bank into the magnet coils. Time-resolved scattering data are collected using a combination of a fast single-photon counting detector, a multichannel scaler, and a high-resolution digital storage oscilloscope. The capabilities of this instrument are used to study a geometrically frustrated system revealing strong magnetostrictive effects in the spin-liquid state.
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Rev. Sci. Instrum. 81, 013101 (2010); http://dx.doi.org/10.1063/1.3276682 (9 pages) Online Publication Date: 4 January 2010
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A folded geometry acousto-optic modulator spatial pulse shaper has been designed for shaping individual pulses from a high power amplified laser. The design preserves the capability of computer programmable amplitude and phase modulation of femtosecond laser pulses. An additional application of genetic algorithm optimization approach for compressing a stretched pulse is also demonstrated for such a pulse shaper. Spectrally and temporally resolved optical gating technique is used to characterize the shaped pulses.
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Single crystal diamond tips for scanning probe microscopy Rev. Sci. Instrum. 81, 013703 (2010); http://dx.doi.org/10.1063/1.3280182 (4 pages) Online Publication Date: 14 January 2010
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Single crystal diamond tips with perfect pyramidal geometry were obtained by a combination of chemical vapor deposition and selective oxidation of polycrystalline films. The parameters of the deposition process were chosen to provide growth of a textured film consisting of micrometer sized diamond crystallites embedded into nanodiamond ballas-like material. The heating of the film in an air environment was used for selective oxidation of the nanodiamond component. The films obtained contain free standing pyramidal single crystal diamond tips oriented by their apexes to the substrate surface. The tips were used for the fabrication of atomic force microscopy probes and their evaluation in comparison to common silicon probes.
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WSXM: A software for scanning probe microscopy and a tool for nanotechnology Rev. Sci. Instrum. 78, 013705 (2007); http://dx.doi.org/10.1063/1.2432410 (8 pages) Online Publication Date: 31 January 2007
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In this work we briefly describe the most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows. The article is structured in three different sections: The introduction is a perspective on the importance of software on scanning probe microscopy. The second section is devoted to describe the general structure of the application; in this section the capabilities of WSXM to read third party files are stressed. Finally, a detailed discussion of some relevant procedures of the software is carried out.
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Calibration of atomic‐force microscope tips Rev. Sci. Instrum. 64, 1868 (1993); http://dx.doi.org/10.1063/1.1143970 (6 pages)
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Images and force measurements taken by an atomic‐force microscope (AFM) depend greatly on the properties of the spring and tip used to probe the sample’s surface. In this article, we describe a simple, nondestructive procedure for measuring the force constant, resonant frequency, and quality factor of an AFM cantilever spring and the effective radius of curvature of an AFM tip. Our procedure uses the AFM itself and does not require additional equipment. |
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Invited Review Article: The Josephson bifurcation amplifier Rev. Sci. Instrum. 80, 111101 (2009); http://dx.doi.org/10.1063/1.3224703 (17 pages) Online Publication Date: 17 November 2009
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We review the theory, fabrication, and implementation of the Josephson bifurcation amplifier (JBA). At the core of the JBA is a nonlinear oscillator based on a reactively shunted Josephson junction. A weak input signal to the amplifier couples to the junction critical current I0 and results in a dispersive shift in the resonator plasma frequency ωp. This shift is enhanced by biasing the junction with a sufficiently strong microwave current Irf to access the nonlinear regime where ωp varies with Irf. For a drive frequency ωd such that Ω = 2Q(1−ωd/ωp)>
 , the oscillator enters the bistable regime where two nondissipative dynamical states OL and OH, which differ in amplitude and phase, can exist. The sharp I0 dependent transition from OL to OH forms the basis for a sensitive digital threshold amplifier. In the vicinity of the bistable regime (Ω<), analog amplification of continuous signals is also possible. We present experimental data characterizing amplifier performance and discuss two specific applications—the readout of superconducting qubits (digital mode) and dispersive microwave magnetometry (analog mode). |
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High-sensitive scanning laser magneto-optical imaging system Rev. Sci. Instrum. 81, 013701 (2010); http://dx.doi.org/10.1063/1.3276710 (7 pages) Online Publication Date: 4 January 2010
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A high-sensitive scanning laser magneto-optical (MO) imaging system has been developed. The system is mainly composed of a laser source, galvano meters, and a high-sensitive differential optical-detector. Preliminary evaluation of system performance by using a Faraday indicator with a Faraday rotation coefficient of 3.47×10−5 rad/μm Oe shows a magnetic sensitivity of about 5 μT, without any need for accumulation or averaging processing. Using the developed MO system we have succeeded in the fast and quantitative imaging of a rotationally symmetric magnetic field distribution around an YBa2Cu3O7−δ (YBCO) strip line applied with dc-biased current, and also succeeded in the detection of quantized fine signals corresponding to magnetic flux quantum generation in a superconducting loop of an YBCO Josephson vortex flow transistor. Thus, the developed system enables us not only to do fast imaging and local signal detection but also to directly evaluate both the strength and direction of a magnetic signal.
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Rev. Sci. Instrum. 75, 2787 (2004); http://dx.doi.org/10.1063/1.1785844 (23 pages) Online Publication Date: 2 September 2004
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Since their invention just over 20 years ago, optical traps have emerged as a powerful tool with broad-reaching applications in biology and physics. Capabilities have evolved from simple manipulation to the application of calibrated forces on—and the measurement of nanometer-level displacements of—optically trapped objects. We review progress in the development of optical trapping apparatus, including instrument design considerations, position detection schemes and calibration techniques, with an emphasis on recent advances. We conclude with a brief summary of innovative optical trapping configurations and applications. |
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Rev. Sci. Instrum. 81, 016103 (2010); http://dx.doi.org/10.1063/1.3280167 (3 pages) Online Publication Date: 14 January 2010
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We present a novel high-resolution technique for single-molecule experiments, viz., differential traveling wave tracking. This is an interference-based scattering technique where we use gold nanoparticles for high scattering intensities and incorporate differential measurements along one in-plane direction to subtract mechanical noise and drift of the system. In addition, out-of-plane distances are measured via scattered light intensity in a total internal reflectance illumination field. In plane, we demonstrate a rms noise level of only 0.10 nm at 10 kHz and less than 0.5 nm at 600 kHz.
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Note: High temperature pulsed solenoid valve Rev. Sci. Instrum. 81, 016101 (2010); http://dx.doi.org/10.1063/1.3271387 (3 pages) Online Publication Date: 7 January 2010
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We have developed a high temperature pulsed solenoid valve with reliable long term operation to at least 400 °C. As in earlier published designs, a needle extension sealing a heated orifice is lifted via solenoid actuation; the solenoid is thermally isolated from the heated orifice region. In this new implementation, superior sealing and reliability were attained by choosing a solenoid that produces considerably larger lifting forces on the magnetically actuated plunger. It is this property that facilitates easily attainable sealing and reliability, albeit with some tradeoff in attainable gas pulse durations. The cost of the solenoid valve employed is quite low and the necessary machining quite simple. Our ultimate level of sealing was attained by making a simple modification to the polished seal at the needle tip. The same sealing tip modification could easily be applied to one of the earlier high T valve designs, which could improve the attainability and tightness of sealing for these implementations.
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Femtosecond pulse shaping using spatial light modulators Rev. Sci. Instrum. 71, 1929 (2000); http://dx.doi.org/10.1063/1.1150614 (32 pages)
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We review the field of femtosecond pulse shaping, in which Fourier synthesis methods are used to generate nearly arbitrarily shaped ultrafast optical wave forms according to user specification. An emphasis is placed on programmable pulse shaping methods based on the use of spatial light modulators. After outlining the fundamental principles of pulse shaping, we then present a detailed discussion of pulse shaping using several different types of spatial light modulators. Finally, new research directions in pulse shaping, and applications of pulse shaping to optical communications, biomedical optical imaging, high power laser amplifiers, quantum control, and laser-electron beam interactions are reviewed. © 2000 American Institute of Physics. |
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Thermal conductivity measurement from 30 to 750 K: the 3ω method Rev. Sci. Instrum. 61, 802 (1990); http://dx.doi.org/10.1063/1.1141498 (7 pages)
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An ac technique for measuring the thermal conductivity of dielectric solids between 30 and 750 K is described. This technique, the 3ω method, can be applied to bulk amorphous solids and crystals as well as amorphous films tens of microns thick. Errors from black‐body radiation are calculated to be less than 2% even at 1000 K. Data for a‐SiO2, Pyrex 7740, and Pyroceram 9606 are compared to results obtained by conventional techniques. |
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Calibration of rectangular atomic force microscope cantilevers Rev. Sci. Instrum. 70, 3967 (1999); http://dx.doi.org/10.1063/1.1150021 (3 pages)
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A method to determine the spring constant of a rectangular atomic force microscope cantilever is proposed that relies solely on the measurement of the resonant frequency and quality factor of the cantilever in fluid (typically air), and knowledge of its plan view dimensions. This method gives very good accuracy and improves upon the previous formulation by Sader et al. [Rev. Sci. Instrum. 66, 3789 (1995)] which, unlike the present method, requires knowledge of both the cantilever density and thickness. © 1999 American Institute of Physics. |
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Rev. Sci. Instrum. 80, 081101 (2009); http://dx.doi.org/10.1063/1.3184828 (23 pages) Online Publication Date: 5 August 2009
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We review the current state of multiphoton microscopy. In particular, the requirements and limitations associated with high-speed multiphoton imaging are considered. A description of the different scanning technologies such as line scan, multifoci approaches, multidepth microscopy, and novel detection techniques is given. The main nonlinear optical contrast mechanisms employed in microscopy are reviewed, namely, multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation. Techniques for optimizing these nonlinear mechanisms through a careful measurement of the spatial and temporal characteristics of the focal volume are discussed, and a brief summary of photobleaching effects is provided. Finally, we consider three new applications of multiphoton microscopy: nonlinear imaging in microfluidics as applied to chemical analysis and the use of two-photon absorption and self-phase modulation as contrast mechanisms applied to imaging problems in the medical sciences.
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Rev. Sci. Instrum. 76, 061101 (2005); http://dx.doi.org/10.1063/1.1927327 (12 pages) Online Publication Date: 26 May 2005
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Nanoelectromechanical systems (NEMS) are drawing interest from both technical and scientific communities. These are electromechanical systems, much like microelectromechanical systems, mostly operated in their resonant modes with dimensions in the deep submicron. In this size regime, they come with extremely high fundamental resonance frequencies, diminished active masses,and tolerable force constants; the quality (Q) factors of resonance are in the range Q ∼ 103–105—significantly higher than those of electrical resonant circuits. These attributes collectively make NEMS suitable for a multitude of technological applications such as ultrafast sensors, actuators, and signal processing components. Experimentally, NEMS are expected to open up investigations of phonon mediated mechanical processes and of the quantum behavior of mesoscopic mechanical systems. However, there still exist fundamental and technological challenges to NEMS optimization. In this review we shall provide a balanced introduction to NEMS by discussing the prospects and challenges in this rapidly developing field and outline an exciting emerging application, nanoelectromechanical mass detection.
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Photoemission electron microscopy using extreme ultraviolet attosecond pulse trains Rev. Sci. Instrum. 80, 123703 (2009); http://dx.doi.org/10.1063/1.3263759 (7 pages) Online Publication Date: 11 December 2009
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We report the first experiments carried out on a new imaging setup, which combines the high spatial resolution of a photoemission electron microscope (PEEM) with the temporal resolution of extreme ultraviolet (XUV) attosecond pulse trains. The very short pulses were provided by high-harmonic generation and used to illuminate lithographic structures and Au nanoparticles, which, in turn, were imaged with a PEEM resolving features below 300 nm. We argue that the spatial resolution is limited by the lack of electron energy filtering in this particular demonstration experiment. Problems with extensive space charge effects, which can occur due to the low probe pulse repetition rate and extremely short duration, are solved by reducing peak intensity while maintaining a sufficient average intensity to allow imaging. Finally, a powerful femtosecond infrared (IR) beam was combined with the XUV beam in a pump-probe setup where delays could be varied from subfemtoseconds to picoseconds. The IR pump beam could induce multiphoton electron emission in resonant features on the surface. The interaction between the electrons emitted by the pump and probe pulses could be observed.
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Design and development of indirectly heated solid cathode for strip type electron gun Rev. Sci. Instrum. 81, 013302 (2010); http://dx.doi.org/10.1063/1.3271539 (10 pages) Online Publication Date: 7 January 2010
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Design analysis of a high power indirectly heated solid cathode (for a 200 kW, 45 kV, and 270° bent strip type electron gun) has been presented. The design approach consists of simulation followed by extensive experimentation with different cathode configurations. The preferred cathode is of trapezoidal section (8×4×2 mm3) with an emitting area of 110×4 mm2 made up of tantalum operating at about 2500 K. The solid cathode at the operating temperature of 2500 K generated a well defined electron beam. Electromagnetic and thermomechanical simulation is used to optimize the shape of the beam. Thermal modeling has also been used to analyze the temperature and stress distribution on the electrodes. The simulation results are validated by experimental measurement.
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Microcantilever sensors for monitoring the evaporation of microdrops of pure liquids and mixtures Rev. Sci. Instrum. 81, 013702 (2010); http://dx.doi.org/10.1063/1.3276716 (8 pages) Online Publication Date: 11 January 2010
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We describe in detail a nonimaging technique that allows the measurement of the mass, the radius, and the contact angle of evaporating sessile microdrops of pure liquids and binary mixtures. The microdrops were deposited onto hydrophobized silicon microcantilevers whose bending and resonance frequency were monitored during drop evaporation. We verify the laws of evaporation kinetics for microdrops with diameters from 80 down to 10 μm. The evaporation of mixtures of water/ethanol drops confirmed previous results with millimeter sized drops. N,N-dimethylformamide drops undergo a transformation from an initial spherical shape to a thin film. Flattening of the drop causes a slowdown of the evaporation kinetics at the end. Two concurring factors are at its origin: the rising disjoining pressure stabilizes the thin liquid film and the increasing radius of curvature of the drop reduces the vapor pressure.
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Surface magneto-optic Kerr effect Rev. Sci. Instrum. 71, 1243 (2000); http://dx.doi.org/10.1063/1.1150496 (13 pages)
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The surface magneto-optic Kerr effect (SMOKE) has significantly impacted research on magnetic thin films. This is due to its sensitivity, local probing nature, and experimental simplicity. The polar and longitudinal Kerr effects are characterized by a complex rotation of the plane of polarization of linearly polarized incident light upon reflection from the surface of a ferromagnetic material. The rotation is directly related to the magnetization of the material within the probing region of the light. Light penetrates into metals >20 nm deep, but the SMOKE technique derives its surface sensitivity from the limited thickness of the deposited magnetic film, which can be as thin as one atomic layer. Basic principles, experimental arrangements, and applications of SMOKE are reviewed in order to acquaint the nonspecialist with the technique and place it into perspective. © 2000 American Institute of Physics. |
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Instrumentation for trace detection of high explosives Rev. Sci. Instrum. 75, 2499 (2004); http://dx.doi.org/10.1063/1.1771493 (14 pages) Online Publication Date: 26 July 2004
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There is at present an urgent need for trace detection of high explosives, with applications to screening of people, packages, luggage, and vehicles. A great concern, because of recent terrorist activities, is for the development of methods that might allow detection and identification of explosives at a stand off distance. Nearly every analytical chemical method has been or is being applied to this problem. This review outlines the properties of explosives that might be utilized in detection schemes, discusses sampling issues, presents recent method developments with particular attention to detection limits, speed of analysis, and portability, and looks towards future developments. |
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