Jump to Content
View Cart
Top 20 Most Read Articles
August 2008
The 20 articles with the most full-text downloads during the month, in descending order.
 |
Rev. Sci. Instrum. 79, 071101 (2008); http://dx.doi.org/10.1063/1.2957649 (11 pages) Online Publication Date: 21 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||||
|
Show Abstract
Piezoelectric tube scanners have emerged as the most widely used nanopositioning technology in modern scanning probe microscopes. Despite their impressive properties, their fast and accurate operations are hindered due to complications such as scan induced mechanical vibrations, hysteresis nonlinearity, creep, and thermal drift. This paper presents an overview of emerging innovative solutions inspired from recent advances in fields such as smart structures, feedback control, and advanced estimation aimed at maximizing positioning precision and bandwidth of piezoelectric tube scanners. The paper presents a thorough survey of the related literature and contains suggestions for future research prospects.
|
||||||||||||||
|
Show PACS
|
||||||||||||||
|
|
The near-field scanning thermal microscope Rev. Sci. Instrum. 79, 073708 (2008); http://dx.doi.org/10.1063/1.2955764 (7 pages) Online Publication Date: 23 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We report on the design, characterization, and performance of a near-field scanning thermal microscope capable to detect thermal heat currents mediated by evanescent thermal electromagnetic fields close to the surface of a sample. The instrument operates in ultrahigh vacuum and retains its scanning tunneling microscope functionality, so that its miniature, micropipette-based thermocouple sensor can be positioned with high accuracy. Heat currents on the order of 10−7 W are registered in z spectroscopy at distances from the sample ranging from 1 to about 30 nm. In addition, the device provides detailed thermographic images of a sample’s surface.
|
|||
|
Show PACS
|
|||
|
|
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
Full Text:
Read Online (HTML)
|
Download PDF
|
|||
|
Show Abstract
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.
|
||||
|
Show PACS
|
||||
|
|
A tabletop femtosecond time-resolved soft x-ray transient absorption spectrometer Rev. Sci. Instrum. 79, 073101 (2008); http://dx.doi.org/10.1063/1.2947737 (13 pages) Online Publication Date: 1 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||||
|
Show Abstract
A laser-based, tabletop instrument is constructed to perform femtosecond soft x-ray transient absorption spectroscopy. Ultrashort soft x-ray pulses produced via high-order harmonic generation of the amplified output of a femtosecond Ti:sapphire laser system are used to probe atomic core-level transient absorptions in atoms and molecules. The results provide chemically specific, time-resolved dynamics with sub-50-fs time resolution. In this setup, high-order harmonics generated in a Ne-filled capillary waveguide are refocused by a gold-coated toroidal mirror into the sample gas cell, where the soft x-ray light intersects with an optical pump pulse. The transmitted high-order harmonics are spectrally dispersed with a homebuilt soft x-ray spectrometer, which consists of a gold-coated toroidal mirror, a uniform-line spaced plane grating, and a soft x-ray charge coupled device camera. The optical layout of the instrument, design of the soft x-ray spectrometer, and spatial and temporal characterizations of the high-order harmonics are described. Examples of static and time-resolved photoabsorption spectra collected on this apparatus are presented.
|
||||||||||||||
|
Show PACS
|
||||||||||||||
|
|
An ultrahigh stability, low-noise laser current driver with digital control Rev. Sci. Instrum. 79, 073107 (2008); http://dx.doi.org/10.1063/1.2953597 (8 pages) Online Publication Date: 11 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We present a low-noise, high modulation-bandwidth design for a laser current driver with excellent long-term stability. The driver improves upon the commonly used Hall–Libbrecht design. The current driver can be operated remotely by way of a microprocessing unit, which controls the current set point digitally. This allows precise repeatability and improved accuracy and stability. It also allows the driver to be placed near the laser for reduced noise and for lower phase lag when using the modulation input. We present the theory of operation for our driver in detail, and give a thorough characterization of its stability, noise, set-point accuracy and repeatability, temperature dependence, transient response, and modulation bandwidth.
|
|||
|
Show PACS
|
|||
|
|
Rev. Sci. Instrum. 79, 083701 (2008); http://dx.doi.org/10.1063/1.2964119 (7 pages) Online Publication Date: 4 August 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We report on a modification of a commercial scanning force microscope (Omicron UHV AFM/STM) operated in noncontact mode (NC-AFM) at room temperature in ultrahigh vacuum yielding a decrease in the spectral noise density from 2757 to 272 fm/
 . The major part of the noise reduction is achieved by an exchange of the originally installed light emitting diode by a laser diode placed outside the vacuum, where the light is coupled into the ultrahigh vacuum chamber via an optical fiber. The setup is further improved by the use of preamplifiers having a bandpass characteristics tailored to the cantilever resonance frequency. The enhanced signal to noise ratio is demonstrated by a comparison of atomic resolution images on CeO2(111) obtained before and after the modification. |
|||
|
Show PACS
|
|||
|
|
Rev. Sci. Instrum. 79, 073108 (2008); http://dx.doi.org/10.1063/1.2957610 (8 pages) Online Publication Date: 17 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
The ability to control ion temperatures is critical for gas phase spectroscopy and has been a challenge in chemical physics. A low-temperature photoelectron spectroscopy instrument has been developed for the investigation of complex anions in the gas phase, including multiply charged anions, solvated species, and biological molecules. The new apparatus consists of an electrospray ionization source, a three dimensional (3D) Paul trap for ion accumulation and cooling, a time-of-flight mass spectrometer, and a magnetic-bottle photoelectron analyzer. A key feature of the new instrument is the capability to cool and tune ion temperatures from 10 to 350 K in the 3D Paul trap, which is attached to the cold head of a closed cycle helium refrigerator. Ion cooling is accomplished in the Paul trap via collisions with a background gas and has been demonstrated by observation of complete elimination of vibrational hot bands in photoelectron spectra of various anions ranging from small molecules to complex species. Further evidence of ion cooling is shown by the observation of H2-physisorbed anions at low temperatures. Cold anions result in better resolved photoelectron spectra due to the elimination of vibrational hot bands and yield more accurate energetic and spectroscopic information. Temperature-dependent studies are made possible for weakly bonded molecular and solvated clusters, allowing thermodynamic information to be obtained.
|
|||
|
Show PACS
|
|||
|
|
Femtosecond pulse shaping using spatial light modulators Rev. Sci. Instrum. 71, 1929 (2000); http://dx.doi.org/10.1063/1.1150614 (32 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
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. |
|||
|
Show PACS
|
|||
|
|
Calibration of rectangular atomic force microscope cantilevers Rev. Sci. Instrum. 70, 3967 (1999); http://dx.doi.org/10.1063/1.1150021 (3 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
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. |
|||
|
Show PACS
|
|||
|
|
Vibration amplitude of a tip-loaded quartz tuning fork during shear force microscopy scanning Rev. Sci. Instrum. 79, 086102 (2008); http://dx.doi.org/10.1063/1.2965137 (3 pages) Online Publication Date: 1 August 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
This Note reports on experimental results obtained with a recently published vision method for in-plane vibration measurement [
Sandoz et al., Rev. Sci. Instrum. 78, 023706 (2007)
]. The latter is applied to a tip-loaded quartz tuning fork frequently used in scanning probe microscopy for shear-force monitoring of the tip-sample distance. The vibration amplitude of the tip-loaded prong is compared to that of the free one and the damping induced by tip-surface interactions is measured. The tuning-fork behavior is characterized during approaches from free space to surface contact. Tip-surface contact is clearly identified by a drastic reduction in the prong vibration amplitude. However, no differences were observed between hydrophilic and hydrophobic surfaces. Experiments reported here show that the vibration amplitude of the quartz tuning fork in free space is a good estimate of the vibration amplitude of the tip interacting with the sample surface during shear force sample-tip feedback. The experimental setup for measuring the amplitude is easily integrated in an inverted microscope setup on which the shear force microscope is installed for simultaneous scanning probe and optical microscopy analysis of the sample.
|
|||
|
Show PACS
|
|||
|
|
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
Full Text:
|
Download PDF
|
||
|
Show Abstract
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. |
|||
|
Show PACS
|
|||
|
|
Digital smoothing of the Langmuir probe I-V characteristic Rev. Sci. Instrum. 79, 073503 (2008); http://dx.doi.org/10.1063/1.2956970 (8 pages) Online Publication Date: 15 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Electrostatic probes or Langmuir probes are the most common diagnostic tools in plasma discharges. The second derivative of the Langmuir probe I-V characteristic is proportional to the electron energy distribution function. Determining the second derivative accurately requires some method of noise suppression. We compare the Savitzky–Golay filter, the Gaussian filter, and polynomial fitting to the Blackman filter for digitally smoothing simulated and measured I-V characteristics. We find that the Blackman filter achieves the most smoothing with minimal distortion for noisy data.
|
|||
|
Show PACS
|
|||
|
|
Laser ablation source for formation and deposition of size-selected metal clusters Rev. Sci. Instrum. 79, 073303 (2008); http://dx.doi.org/10.1063/1.2952503 (8 pages) Online Publication Date: 1 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
This work describes construction of a source and optimisation of its parameters for production of cluster ion beams using material ablation by the second harmonic of a Nd:YAG laser (532 nm). The influence of different source parameters such as carrier gas pressure, laser power, delay time between gas, and laser pulses as well as nozzle configuration on the cluster formation are studied. For the current experiments the laser ablation cluster source was optimized for production of Con+ cluster ions. Clusters with n up to 150 atoms are registered by a time-of-flight mass spectrometer. Deposition of size-selected Co50+ clusters with kinetic energies in the interval of 250–4850 eV/cluster on highly ordered pyrolytic graphite is studied. At the highest impact energies the clusters are implanted. Craters and well-like structures can be seen by scanning tunneling microscopy at impact spots. A decrease in cluster kinetic energy leads to formation of bumplike structures which probably represent damaged graphite areas with incorporated Co atoms. Further decrease in the cluster impact energy to the level of 450–250 eV/cluster creates condition for so-called cluster pinning when the cluster constituents are intact but the energy transferred to the graphite is still enough to produce radiation defects to which the cluster is bound.
|
|||
|
Show PACS
|
|||
|
|
Rev. Sci. Instrum. 79, 073706 (2008); http://dx.doi.org/10.1063/1.2956977 (8 pages) Online Publication Date: 16 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Conventional Raman spectroscopy (RS) suffers from low spatial resolution and low detection sensitivity due to the optical diffraction limit and small interaction cross sections. It has been reported that a highly localized and significantly enhanced electromagnetic field could be generated in the proximity of a metallic tip illuminated by a laser beam. In this study, a tip-enhanced RS system was developed to both improve the resolution and enhance the detection sensitivity using the tip-enhanced near-field effects. This instrument, by combining RS with a scanning tunneling microscope and side-illumination optics, demonstrated significant enhancement on both optical sensitivity and spatial resolution using either silver (Ag)-coated tungsten (W) tips or gold (Au) tips. The sensitivity improvement was verified by observing the enhancement effects on silicon (Si) substrates. Lateral resolution was verified to be below 100 nm by mapping Ag nanostructures. By deploying the depolarization technique, an apparent enhancement of 175% on Si substrates was achieved. Furthermore, the developed instrument features fast and reliable optical alignment, versatile sample adaptability, and effective suppression of far-field signals.
|
|||
|
Show PACS
|
|||
|
|
A “tabletop” electrostatic ion storage ring: Mini-Ring Rev. Sci. Instrum. 79, 075109 (2008); http://dx.doi.org/10.1063/1.2957609 (8 pages) Online Publication Date: 30 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We report on the design, construction, and commissioning of a novel electrostatic ion storage ring of small dimensions—in the following referred to as “Mini-Ring.” Mini-Ring consists of four horizontal parallel-plate deflectors and two conical electrostatic mirrors. Ions are injected through the two deflectors on the injection side and off axis with respect to the conical mirrors which face each other. The first injection deflector, originally at zero voltage, is switched to its set value such that the ions after one turn follow stable trajectories of lengths of roughly 30 cm. This design reduces the number of electrodes necessary to guide the ion beam through the ring in stable orbits. The six elements (deflectors and mirrors) are placed on a common grounded plate—the tabletop. Here, we present the design, ion trajectory simulations, and results of the first test experiments demonstrating the successful room-temperature operation of Mini-Ring at background pressures of 10−6–10−7 mbar.
|
|||
|
Show PACS
|
|||
|
|
Diffractive-refractive optics: X-ray collimator Rev. Sci. Instrum. 79, 073105 (2008); http://dx.doi.org/10.1063/1.2949386 (4 pages) Online Publication Date: 10 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Diffractive-refractive optics are x-ray focusing monochromators based on the diffraction on profiled crystal surface. Diffraction on longitudinal parabolic groove machined in crystal surface forms a sagittaly focused synchrotron radiation beam. Such kind of monochromator may be realized as a crystal with parabolic hole, where the beam is diffracted on the inner wall of the hole. Two such asymmetrically cut crystals set into antiparallel position, creating a dispersive (+,−,−,+) arrangement, form a sagittaly focusing x-ray monochromator which should be practically aberration-free. The focusing properties of such kind of monochromator are discussed in detail and it is shown for the first time that it can be used not only for focusing but also for creating highly parallel monochromatic beam in the broad region of the Bragg angles. This device with parabolic hole has not been tested experimentally yet.
|
|||
|
Show PACS
|
|||
|
|
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)
Full Text:
|
Download PDF
|
||
|
Show Abstract
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. |
|||
|
Show PACS
|
|||
|
|
Rev. Sci. Instrum. 79, 073701 (2008); http://dx.doi.org/10.1063/1.2952058 (5 pages) Online Publication Date: 1 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
|||
|
Show Abstract
A new configuration of conductive atomic force microscope (CAFM) is presented, which is based in a standard CAFM where the typical I-V converter has been replaced by a log I-V amplifier. This substitution extends the current dynamic range from 1–100 pA to 1 pA–1 mA. With the broadening of the current dynamic range, the CAFM can access new applications, such as the reliability evaluation of metal-oxide-semiconductor gate dielectrics. As an example, the setup has been tested by analyzing breakdown spots induced in SiO2 layers.
|
||||
|
Show PACS
|
||||
|
|
Rev. Sci. Instrum. 79, 084101 (2008); http://dx.doi.org/10.1063/1.2960569 (6 pages) Online Publication Date: 1 August 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We present the design and performance of a homebuilt high-pressure and high-temperature reactor equipped with a high-resolution scanning tunneling microscope (STM) for catalytic studies. In this design, the STM body, sample, and tip are placed in a small high pressure reactor ( ∼ 19 cm3) located within an ultrahigh vacuum (UHV) chamber. A sealable port on the wall of the reactor separates the high pressure environment in the reactor from the vacuum environment of the STM chamber and permits sample transfer and tip change in UHV. A combination of a sample transfer arm, wobble stick, and sample load-lock system allows fast transfer of samples and tips between the preparation chamber, high pressure reactor, and ambient environment. This STM reactor can work as a batch or flowing reactor at a pressure range of 10−13 to several bars and a temperature range of 300–700 K. Experiments performed on two samples both in vacuum and in high pressure conditions demonstrate the capability of in situ investigations of heterogeneous catalysis and surface chemistry at atomic resolution at a wide pressure range from UHV to a pressure higher than 1 atm.
|
|||
|
Show PACS
|
|||
|
|
Monte Carlo simulations of microchannel plate detectors. I. Steady-state voltage bias results Rev. Sci. Instrum. 79, 073104 (2008); http://dx.doi.org/10.1063/1.2949119 (7 pages) Online Publication Date: 10 July 2008
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
X-ray detectors based on straight-channel microchannel plates (MCPs) are a powerful diagnostic tool for two-dimensional, time-resolved imaging and time-resolved x-ray spectroscopy in the fields of laser-driven inertial confinement fusion and fast Z-pinch experiments. Understanding the behavior of microchannel plates as used in such detectors is critical to understanding the data obtained. The subject of this paper is a Monte Carlo computer code we have developed to simulate the electron cascade in a MCP under a static applied voltage. Also included in the simulation is elastic reflection of low-energy electrons from the channel wall, which is important at lower voltages. When model results were compared to measured MCP sensitivities, good agreement was found. Spatial resolution simulations of MCP-based detectors were also presented and found to agree with experimental measurements.
|
|||
|
Show PACS
|
|||
This Publication
Scitation
Google Scholar
PubMed