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Top 20 Most Read Articles
August 2010
The 20 articles with the most full-text downloads during the month, in descending order.
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Optical coherence tomography monitoring of angioplasty balloon inflation in a deployment tester Rev. Sci. Instrum. 81, 083101 (2010); http://dx.doi.org/10.1063/1.3465556 (8 pages) Online Publication Date: 2 August 2010
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We present an innovative integration of an intravascular optical coherence tomography probe into a computerized balloon deployment system to monitor the balloon inflation process. The high-resolution intraluminal imaging of the balloon provides a detailed assessment of the balloon quality and, consequently, a technique to improve the balloon manufacturing process. A custom-built swept-source optical coherence tomography system is used for real-time imaging. A semicompliant balloon with a nominal diameter of 4 mm is fabricated for the experiments. Imaging results correspond to balloon deployment in air and inside an artery phantom. A characterization of the balloon diameter, wall thickness, compliance, and elastic modulus is provided, based on image segmentation. Using the images obtained from the probe pullback, a three-dimensional visualization of the inflated balloon is presented.
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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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Inductive conductivity tensor measurement for flowline or material samples Rev. Sci. Instrum. 81, 075102 (2010); http://dx.doi.org/10.1063/1.3449320 (9 pages) Online Publication Date: 2 July 2010
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Present-day galvanic-based electrical conductivity measurements are hampered by limitations and necessary corrections, especially in the domain of geological core analysis. Low-accuracy techniques such as crucible, two-electrode, and four-electrode are constricted by current-path requirements, while high-accuracy techniques are time consuming and have limited domains of applicability. We present a novel apparatus capable of electrical conductivity tensor measurements in a noninvasive, noncontact, inductive manner with resolution from 5 mS/m. Inspired by the triaxial induction logging technology appearing in the oil patch today, our apparatus is naturally applicable in a novel way not only to anisotropic geological core analysis but also to arbitrary material samples and flowline systems.
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High-resolution friction force microscopy under electrochemical control Rev. Sci. Instrum. 81, 083701 (2010); http://dx.doi.org/10.1063/1.3470107 (11 pages) Online Publication Date: 2 August 2010
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We report the design and development of a friction force microscope for high-resolution studies in electrochemical environments. The design choices are motivated by the experimental requirements of atomic-scale friction measurements in liquids. The noise of the system is analyzed based on a methodology for the quantification of all the noise sources. The quantitative contribution of each noise source is analyzed in a series of lateral force measurements. Normal force detection is demonstrated in a study of the solvation potential in a confined liquid, octamethylcyclotetrasiloxane. The limitations of the timing resolution of the instrument are discussed in the context of an atomic stick-slip measurement. The instrument is capable of studying the atomic friction contrast between a bare Au(111) surface and a copper monolayer deposited at underpotential conditions in perchloric acid.
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A lightweight near-infrared spectrometer for the detection of trace atmospheric species Rev. Sci. Instrum. 81, 083102 (2010); http://dx.doi.org/10.1063/1.3455827 (11 pages) Online Publication Date: 3 August 2010
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This paper describes the development and deployment of a lightweight in situ near-infrared tunable diode laser absorption spectrometer (TDLAS) for balloon-borne measurements of trace species such as methane in the upper troposphere and stratosphere. The key feature of the instrument design is its ability to provide high sensitivity measurements with better than 1 part in 106 Hz−1/2 optical sensitivity in a lightweight package weighing as little as 6 kg, and maintaining this level of performance over the wide range of conditions experienced during field measurements. The absolute accuracy for methane measurements is approximately 10% limited by uncertainties in determining the gas temperature in the measurement volume. The high sensitivity and high temporal resolution (2.3 s measurement period) enables details of the fine-scale structure in the atmosphere to be measured. The TDLAS instrument has been used on a number of major international measurement campaigns. Intercomparison with other instruments during these campaigns have confirmed the comparability of the results from this instrument with measurements made by a range of other techniques, and demonstrated the instruments suitability for studies of atmospheric dynamics, transport, and mixing processes.
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Rev. Sci. Instrum. 81, 063107 (2010); http://dx.doi.org/10.1063/1.3441983 (5 pages) Online Publication Date: 17 June 2010
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An x-ray spectrometer devoted to dynamical studies of transient systems using the x-ray absorption fine spectroscopy technique is presented in this article. Using an ultrafast laser-induced x-ray source, this optical device based on a set of two potassium acid phthalate conical crystals allows the extraction of x-ray absorption near-edge spectroscopy structures following the Al absorption K edge. The proposed experimental protocol leads to a measurement of the absorption spectra free from any crystal reflectivity defaults and shot-to-shot x-ray spectral fluctuation. According to the detailed analysis of the experimental results, a spectral resolution of 0.7 eV rms and relative fluctuation lower than 1% rms are achieved, demonstrated to be limited by the statistics of photon counting on the x-ray detector.
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Low voltage operation of plasma focus Rev. Sci. Instrum. 81, 083501 (2010); http://dx.doi.org/10.1063/1.3470917 (4 pages) Online Publication Date: 2 August 2010
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Plasma foci of compact sizes and operating with low energies (from tens of joules to few hundred joules) have found application in recent years and have attracted plasma-physics scientists and engineers for research in this direction. We are presenting a low energy and miniature plasma focus which operates from a capacitor bank of 8.4 μF capacity, charged at 4.2–4.3 kV and delivering approximately 52 kA peak current at approximately 60 nH calculated circuit inductance. The total circuit inductance includes the plasma focus inductance. The reported plasma focus operates at the lowest voltage among all reported plasma foci so far. Moreover the cost of capacitor bank used for plasma focus is nearly 20 U.S. dollars making it very cheap. At low voltage operation of plasma focus, the initial breakdown mechanism becomes important for operation of plasma focus. The quartz glass tube is used as insulator and breakdown initiation is done on its surface. The total energy of the plasma focus is approximately 75 J. The plasma focus system is made compact and the switching of capacitor bank energy is done by manual operating switch. The focus is operated with hydrogen and deuterium filled at 1–2 mbar.
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Note: Multiscale scanning probe microscopy Rev. Sci. Instrum. 81, 086101 (2010); http://dx.doi.org/10.1063/1.3473935 (3 pages) Online Publication Date: 16 August 2010
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Combining the nanoscopic and macroscopic worlds is a serious challenge common to numerous scientific fields, from physics to biology. In this paper, we demonstrate nanometric resolution over a millimeter range by means of atomic-force microscopy using metrological stage. Nanometric repeatability and millimeter range open up the possibility of probing components and materials combining multiscale properties i.e., engineered nanomaterials. Multiscale probing is not limited to atomic-force microscopy and can be extended to any type of scanning probe technique in nanotechnology, including piezoforce microscopy, electrostatic-force microscopy, and scanning near-field optical microscopy.
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Rev. Sci. Instrum. 78, 031101 (2007); http://dx.doi.org/10.1063/1.2709758 (20 pages) Online Publication Date: 30 March 2007
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The technique of atom probe tomography (APT) is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future. APT delivers the highest spatial resolution (sub-0.3-nm) three-dimensional compositional information of any microscopy technique. Recently, APT has changed dramatically with new hardware configurations that greatly simplify the technique and improve the rate of data acquisition. In addition, new methods have been developed to fabricate suitable specimens from new classes of materials. Applications of APT have expanded from structural metals and alloys to thin multilayer films on planar substrates, dielectric films, semiconducting structures and devices, and ceramic materials. This trend toward a broader range of materials and applications is likely to continue.
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Tunable ultrafast extreme ultraviolet source for time- and angle-resolved photoemission spectroscopy Rev. Sci. Instrum. 81, 073108 (2010); http://dx.doi.org/10.1063/1.3460267 (7 pages) Online Publication Date: 20 July 2010
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We present a laser-based apparatus suitable for visible pump/extreme UV (XUV) probe time-, energy-, and angle-resolved photoemission spectroscopy utilizing high-harmonic generation from a noble gas. Tunability in a wide range of energies (currently 20–36 eV) is achieved by using a time-delay compensated monochromator, which also preserves the ultrashort duration of the XUV pulses. Using an amplified laser system at 10 kHz repetition rate, approximately 109–1010 photons/s per harmonic are made available for photoelectron spectroscopy. Parallel energy and momentum detection is carried out in a hemispherical electron analyzer coupled with an imaging detector. First applications demonstrate the capabilities of the instrument to easily select the probe wavelength of choice, to obtain angle-resolved photoemission maps (GaAs and URu2Si2), and to trace ultrafast electron dynamics in an optically excited semiconductor (Ge).
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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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Rev. Sci. Instrum. 68, 3277 (1997); http://dx.doi.org/10.1063/1.1148286 (19 pages)
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We summarize the problem of measuring an ultrashort laser pulse and describe in detail a technique that completely characterizes a pulse in time: frequency-resolved optical gating. Emphasis is placed on the choice of experimental beam geometry and the implementation of the iterative phase-retrieval algorithm that together yield an accurate measurement of the pulse time-dependent intensity and phase over a wide range of circumstances. We compare several commonly used beam geometries, displaying sample traces for each and showing where each is appropriate, and we give a detailed description of the pulse-retrieval algorithm for each of these cases. © 1997 American Institute of Physics. |
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Electrostatic actuator probe with curved electrodes for time-of-flight scanning force microscopy Rev. Sci. Instrum. 81, 083702 (2010); http://dx.doi.org/10.1063/1.3469796 (6 pages) Online Publication Date: 11 August 2010
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In this study, we fabricated an electrostatic actuator probe having curved electrodes and evaluated its applicability for use in time-of-flight scanning force microscopy. In this probe, the end position of a cantilever with a tip is switched through electrostatic pull-in effect; the measurement modes can be changed between mass analysis and scanning force microscopy (SFM) modes. We achieved a large displacement of 400 μm for changing working modes. To prevent electrical shortage of the probe and curved electrodes, stoppers were formed along the curved electrodes. Because of the pull-in effect, the spring constant and resonance frequency increased through stiction of the cantilever to the stoppers. Using the fabricated probe, the SFM imaging of a sample featuring a 2-μm-pitch Au grid was demonstrated.
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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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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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Invited Article: High-pressure techniques for condensed matter physics at low temperature Rev. Sci. Instrum. 81, 041301 (2010); http://dx.doi.org/10.1063/1.3400212 (8 pages) Online Publication Date: 20 April 2010
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Condensed matter experiments at high pressure accentuate the need for accurate pressure scales over a broad range of temperatures, as well as placing a premium on a homogeneous pressure environment. However, challenges remain in diamond anvil cell technology, including both the quality of various pressure transmitting media and the accuracy of secondary pressure scales at low temperature. We directly calibrate the ruby fluorescence R1 line shift with pressure at T = 4.5 K using high-resolution x-ray powder diffraction measurements of the silver lattice constant and its known equation of state up to P = 16 GPa. Our results reveal a ruby pressure scale at low temperatures that differs by 6% from the best available ruby scale at room T. We also use ruby fluorescence to characterize the pressure inhomogeneity and anisotropy in two representative and commonly used pressure media, helium and methanol:ethanol 4:1, under the same preparation conditions for pressures up to 20 GPa at T = 5 K. Contrary to the accepted wisdom, both media show equal levels of pressure inhomogeneity measured over the same area, with a consistent ΔP/P per unit area of ±1.8 %/(104 μm2) from 0 to 20 GPa. The helium medium shows an essentially constant deviatoric stress of 0.021±0.011 GPa up to 16 GPa, while the methanol:ethanol mixture shows a similar level of anisotropy up to 10 GPa, above which the anisotropy increases. The quality of both pressure media is further examined under the more stringent requirements of single crystal x-ray diffraction at cryogenic temperature. For such experiments we conclude that the ratio of sample-to-pressure chamber volume is a critical parameter in maintaining sample quality at high pressure, and may affect the choice of pressure medium.
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A battery-based, low-noise voltage source Rev. Sci. Instrum. 81, 064706 (2010); http://dx.doi.org/10.1063/1.3455199 (7 pages) Online Publication Date: 30 June 2010
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A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of ±15 and ±5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7×10−7 over 6.5 h and a noise level equal or smaller than 30 nV/
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Photoacoustic imaging in biomedicine Rev. Sci. Instrum. 77, 041101 (2006); http://dx.doi.org/10.1063/1.2195024 (22 pages) Online Publication Date: 17 April 2006
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Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) has the potential to image animal or human organs, such as the breast and the brain, with simultaneous high contrast and high spatial resolution. This article provides an overview of the rapidly expanding field of photoacoustic imaging for biomedical applications. Imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography with unfocused transducers, are introduced. Special emphasis is placed on computed tomography, including reconstruction algorithms, spatial resolution, and related recent experiments. Promising biomedical applications are discussed throughout the text, including (1) tomographic imaging of the skin and other superficial organs by laser-induced photoacoustic microscopy, which offers the critical advantages, over current high-resolution optical imaging modalities, of deeper imaging depth and higher absorption contrasts, (2) breast cancer detection by near-infrared light or radio-frequency–wave-induced photoacoustic imaging, which has important potential for early detection, and (3) small animal imaging by laser-induced photoacoustic imaging, which measures unique optical absorption contrasts related to important biochemical information and provides better resolution in deep tissues than optical imaging.
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A new tandem mass spectrometer for photofragment spectroscopy of cold, gas-phase molecular ions Rev. Sci. Instrum. 81, 073107 (2010); http://dx.doi.org/10.1063/1.3458014 (7 pages) Online Publication Date: 20 July 2010
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We present here the design of a new tandem mass spectrometer that combines an electrospray ion source with a cryogenically cooled ion trap for spectroscopic studies of cold, gas-phase ions. The ability to generate large ions in the gas phase without fragmentation, cool them to ∼ 10 K in an ion trap, and perform photofragment spectroscopy opens up new possibilities for spectroscopic characterization of large biomolecular ions. The incorporation of an ion funnel, together with a number of small enhancements, significantly improves the sensitivity, signal stability, and ease of use compared with the previous instrument built in our laboratory.
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