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Top 20 Most Read Articles
January 2008
The 20 articles with the most full-text downloads during the month, in descending order.
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Rev. Sci. Instrum. 78, 121301 (2007); http://dx.doi.org/10.1063/1.2821148 (15 pages) Online Publication Date: 12 December 2007
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Experimental and theoretical aspects of obtaining the magnetic information carried by laser beams diffracted from an array of micro- or nanosized magnetic objects are reviewed. We report on the fundamentals of vector magneto-optic Kerr effect (MOKE), Bragg-MOKE, and second-order effects in the Kerr signal in longitudinal Kerr geometry as well as on an experimental setup used for vector and Bragg-MOKE experiments. The vector and Bragg-MOKE technique in combination with micromagnetic simulation is a reliable tool for measuring the complete magnetization vector and for characterizing the reversal mechanism of lateral magnetic nanostructures. We discuss the Bragg-MOKE effect for three standard domain configurations during the magnetization reversal process and present the expected behavior of the magnetic hysteresis loops.
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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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Rev. Sci. Instrum. 78, 120901 (2007); http://dx.doi.org/10.1063/1.2821150 (2 pages) Online Publication Date: 12 December 2007
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Rev. Sci. Instrum. 78, 081101 (2007); http://dx.doi.org/10.1063/1.2754076 (8 pages) Online Publication Date: 6 August 2007
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Cantilevers with single micro- or nanoparticle probes have been widely used for atomic force microscopy surface force measurements and apertureless scanning near-field optical microscopy applications. In this article, I critically review the particle attachment and modification techniques currently available, to help researchers choose the appropriate techniques for specific applications.
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Time‐of‐Flight Mass Spectrometer with Improved Resolution Rev. Sci. Instrum. 26, 1150 (1955); http://dx.doi.org/10.1063/1.1715212 (8 pages) Online Publication Date: 29 December 2004
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A new type of ion gun is described which greatly improves the resolution of a nonmagnetic time‐of‐flight mass spectrometer. The focusing action of this gun is discussed and analyzed mathematically. The validity of the analysis and the practicability of the gun are demonstrated by the spectra obtained. The spectrometer is capable of measuring the relative abundance of adjacent masses well beyond 100 amu. |
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Novel instrument for surface plasmon polariton tracking in space and time Rev. Sci. Instrum. 79, 013704 (2008); http://dx.doi.org/10.1063/1.2825463 (10 pages) Online Publication Date: 10 January 2008
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We describe the realization of a phase-sensitive and ultrafast near-field microscope, optimized for investigation of surface plasmon polariton propagation. The apparatus consists of a homebuilt near-field microscope that is incorporated in Mach-Zehnder-type interferometer which enables heterodyne detection. We show that this microscope is able to measure dynamical properties of both photonic and plasmonic systems with phase sensitivity.
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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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Nanosecond electro-optical switching with a repetition rate above 20 MHz Rev. Sci. Instrum. 78, 124702 (2007); http://dx.doi.org/10.1063/1.2822101 (4 pages) Online Publication Date: 11 December 2007
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We describe an electro-optical switch based on a commercial electro-optic modulator (modified for high-speed operation) and a 340 V pulser having a rise time of 2.2 ns (at 250 V). It can produce arbitrary pulse patterns with an average repetition rate beyond 20 MHz. It uses a grounded-grid triode driven by transmitting power transistors. We discuss variations that enable analog operation, use the step-recovery effect in bipolar transistors, or offer other combinations of output voltage, size, and cost.
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Microcantilever actuation via periodic internal heating Rev. Sci. Instrum. 78, 126102 (2007); http://dx.doi.org/10.1063/1.2818805 (3 pages) Online Publication Date: 11 December 2007
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This paper reports electrothermal actuation of silicon microcantilevers having integrated resistive heaters. Periodic electrical excitation induced periodic resistive heating in the cantilever, while the cantilever deflection was monitored with a photodetector. Excitation was either at the cantilever resonant frequency, f0, f0/2, or f0/3. When the time averaged maximum cantilever temperature was 174 °C, the cantilever out-of-plane actuation amplitude was 484 nm near the cantilever resonance frequency of 24.9 kHz. This actuation was sufficiently large to operate the cantilever in intermittent contact mode and scan a calibration grating of height of 20 nm.
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Novel miniature electrostatic generator Rev. Sci. Instrum. 79, 015103 (2008); http://dx.doi.org/10.1063/1.2829988 (5 pages) Online Publication Date: 10 January 2008
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A new and unusual design for an electrostatic high voltage generator is introduced. The prototype device built by the author can generate a voltage up to approximately 180 kV; yet, its physical size is only a fraction of the size of a comparable Van de Graaff generator. In recent years there has been increasing demand for high voltage generators that are also very compact and lightweight. The new design introduced here fulfills that requirement.
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A hyperspectral fluorescence lifetime probe for skin cancer diagnosis Rev. Sci. Instrum. 78, 123101 (2007); http://dx.doi.org/10.1063/1.2818785 (7 pages) Online Publication Date: 4 December 2007
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The autofluorescence of biological tissue can be exploited for the detection and diagnosis of disease but, to date, its complex nature and relatively weak signal levels have impeded its widespread application in biology and medicine. We present here a portable instrument designed for the in situ simultaneous measurement of autofluorescence emission spectra and temporal decay profiles, permitting the analysis of complex fluorescence signals. This hyperspectral fluorescence lifetime probe utilizes two ultrafast lasers operating at 355 and 440 nm that can excite autofluorescence from many different biomolecules present in skin tissue including keratin, collagen, nicotinamide adenine dinucleotide (phosphate), and flavins. The instrument incorporates an optical fiber probe to provide sample illumination and fluorescence collection over a millimeter-sized area. We present a description of the system, including spectral and temporal characterizations, and report the preliminary application of this instrument to a study of recently resected (<2 h) ex vivo skin lesions, illustrating its potential for skin cancer detection and diagnosis.
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Mid-infrared optical coherence tomography Rev. Sci. Instrum. 78, 123108 (2007); http://dx.doi.org/10.1063/1.2821609 (7 pages) Online Publication Date: 18 December 2007
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A time domain optical coherence tomography (OCT) system is described that uses mid-infrared light (6–8 μm). To the best of our knowledge, this is the first OCT system that operates in the mid-infrared spectral region. It has been designed to characterize bioengineered tissues in terms of their structure and biochemical composition. The system is based upon a free-space Michelson interferometer with a germanium beam splitter and a liquid nitrogen cooled HgCdTe detector. A key component of this work has been the development of a broadband quantum cascade laser source (InGaAs/AlInAs containing 11 different active regions of the three well vertical transition type) that emits continuously over the 6–8 μm wavelength range. This wavelength range corresponds to the so called “mid-infrared fingerprint region” which exhibits well-defined absorption bands that are specifically attributable to the absorbing molecules. Therefore, this technology provides an opportunity for optical coherence molecular imaging without the need for molecular contrast agents. Preliminary measurements are presented.
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Phase-locked scanning interferometer for frequency stabilization of multiple lasers Rev. Sci. Instrum. 78, 123103 (2007); http://dx.doi.org/10.1063/1.2818773 (7 pages) Online Publication Date: 6 December 2007
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We report a simple scheme for stabilizing and tuning the length of a conventional piezo-driven optical cavity against the resonant transmission of a master laser. In contrast with other schemes, we drive the piezo at its mechanical resonance of 5 kHz over an amplitude equivalent to one free spectral range and use a feedback circuit that incorporates phase-sensitive detection of the master-laser transmission. The bandwidth of our cavity-lock circuit is limited only by the resonance frequency of the cavity piezo and is 1.4 kHz. The stabilized mean cavity length reaches in 30 s a minimum Allan deviation of ∼ 10 kHz (a length stability of 20 parts per trillion) equaling that of the polarization-stabilized He–Ne we use as our master laser. Here, we investigate the mechanical characteristics of the cavity, describe the lock circuit and its measured performance, and provide simple analytical relations between the phase-sensitive signal and cavity displacement. Our setup economizes the cost and amount of equipment necessary for stabilizing multiple continuous-wave lasers operating at different wavelengths.
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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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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. 79, 013101 (2008); http://dx.doi.org/10.1063/1.2827517 (4 pages) Online Publication Date: 2 January 2008
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We discuss a simple time of flight technique for measurement of temperature of a cold cloud in a magneto-optical trap (MOT). The technique is based on spatiotemporal fluorescence imaging of the cloud that is allowed to undergo one-dimensional expansion in the presence of the orthogonal two-dimensional configuration of laser beams by temporal modulation of a pair of counterpropagating trapping beams in the MOT. We show that, in the time scale 0 ⩽ t<5 ms, the expansion of the cloud is ballistic and the temperature can be extracted from the time variation of the rms size of the cloud in the expansion direction. The reliability of the technique has been established by comparing the results with release and recapture method, and also by fitting them to the known temperature scaling law.
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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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Rev. Sci. Instrum. 78, 123701 (2007); http://dx.doi.org/10.1063/1.2821610 (7 pages) Online Publication Date: 10 December 2007
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We describe the development and the capabilities of an advanced system for nanoscale electrical transport studies. This system consists of a low temperature four-probe scanning tunneling microscope (STM) and a high-resolution scanning electron microscope coupled to a molecular-beam epitaxy sample preparation chamber. The four STM probes can be manipulated independently with subnanometer precision, enabling atomic resolution STM imaging and four-point electrical transport study of surface electronic systems and nanostructured materials at temperatures down to 10 K. Additionally, an integrated energy analyzer allows for scanning Auger microscopy to probe chemical species of nanostructures. Some testing results are presented.
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Cantilever transducers as a platform for chemical and biological sensors Rev. Sci. Instrum. 75, 2229 (2004); http://dx.doi.org/10.1063/1.1763252 (25 pages) Online Publication Date: 21 June 2004
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Since the late 1980s there have been spectacular developments in micromechanical or microelectro-mechanical (MEMS) systems which have enabled the exploration of transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result an innovative family of chemical and biological sensors has emerged. In this article, we discuss sensors with transducers in a form of cantilevers. While MEMS represents a diverse family of designs, devices with simple cantilever configurations are especially attractive as transducers for chemical and biological sensors. The review deals with four important aspects of cantilever transducers: (i) operation principles and models; (ii) microfabrication; (iii) figures of merit; and (iv) applications of cantilever sensors. We also provide a brief analysis of historical predecessors of the modern cantilever sensors. © 2004 American Institute of Physics. |
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Rev. Sci. Instrum. 78, 123104 (2007); http://dx.doi.org/10.1063/1.2818806 (4 pages) Online Publication Date: 6 December 2007
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We have developed a highly brilliant xenon (Xe) discharge lamp operated by microwave-induced electron cyclotron resonance (ECR) for ultrahigh-resolution bulk-sensitive photoemission spectroscopy (PES). We observed at least eight strong radiation lines from neutral or singly ionized Xe atoms in the energy region of 8.4–10.7 eV. The photon flux of the strongest Xe I resonance line at 8.437 eV is comparable to that of the He Iα line (21.218 eV) from the He-ECR discharge lamp. Stable operation for more than 300 h is achieved by efficient air-cooling of a ceramic tube in the resonance cavity. The high bulk sensitivity and high-energy resolution of PES using the Xe lines are demonstrated for some typical materials.
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