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Feb 2006

Volume 77, Issue 2, Articles (02xxxx)

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Vacuum arc deposition devices

R. L. Boxman and V. N. Zhitomirsky

Rev. Sci. Instrum. 77, 021101 (2006); http://dx.doi.org/10.1063/1.2169539 (15 pages) | Cited 18 times

Online Publication Date: 14 February 2006

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The vacuum arc is a high-current, low-voltage electrical discharge which produces a plasma consisting of vaporized and ionized electrode material. In the most common cathodic arc deposition systems, the arc concentrates at minute cathode spots on the cathode surface and the plasma is emitted as a hypersonic jet, with some degree of contamination by molten droplets [known as macroparticles (MPs)] of the cathode material. In vacuum arc deposition systems, the location and motion of the cathode spots are confined to desired surfaces by an applied magnetic field and shields around undesired surfaces. Substrates are mounted on a holder so that they intercept some portion of the plasma jet. The substrate often provides for negative bias to control the energy of depositing ions and heating or cooling to control the substrate temperature. In some systems, a magnetic field is used to guide the plasma around an obstacle which blocks the MPs. These elements are integrated with a deposition chamber, cooling, vacuum gauges and pumps, and power supplies to produce a vacuum arc deposition system.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
52.77.Dq Plasma-based ion implantation and deposition
52.50.Dg Plasma sources
52.40.Hf Plasma-material interactions; boundary layer effects
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Design of a high-efficiency grazing incidence monochromator with multilayer-coated laminar gratings for the 1–6 keV region

Masato Koike, Masahiko Ishino, and Hiroyuki Sasai

Rev. Sci. Instrum. 77, 023101 (2006); http://dx.doi.org/10.1063/1.2166668 (4 pages) | Cited 1 time

Online Publication Date: 9 February 2006

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A grazing incidence objective monochromator consisting of a spherical mirror, a varied-line-spacing plane grating with multilayered coating, a movable plane multilayered mirror, and a fixed exit slit for the 1–6 keV region has been designed. The included angle at the grating was chosen to satisfy the grating equation and extended Bragg condition simultaneously. The aberration was corrected by means of a hybrid design method. A spectral resolving power of ∼ 600– ∼ 6000 and a throughput of ∼ 2%– ∼ 40% is expected for the monochromator when used in an undulator beamline.
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07.85.-m X- and γ-ray instruments
42.15.Eq Optical system design
42.79.Dj Gratings
42.79.Wc Optical coatings
42.79.Bh Lenses, prisms and mirrors
42.15.Fr Aberrations

Characterization of wave-front corrected 100 TW, 10 Hz laser pulses with peak intensities greater than 1020 W/cm2

Yutaka Akahane, Jinglong Ma, Yuji Fukuda, Makoto Aoyoma, Hiromitsu Kiriyama, Julia V. Sheldakova, Alexis V. Kudryashov, and Koichi Yamakawa

Rev. Sci. Instrum. 77, 023102 (2006); http://dx.doi.org/10.1063/1.2166669 (7 pages) | Cited 11 times

Online Publication Date: 9 February 2006

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An improvement of laser-focused peak intensity has been achieved in a JAERI 100 TW Ti:sapphire chirped-pulse amplifier chain with a feedback controlled adaptive optics system operating at a 10 Hz repetition rate. The Strehl ratio was enhanced to 0.8 by means of a Bimorph deformable mirror with a Shack-Hartmann wave-front sensor. Measurements of optical parameters of the laser pulse and an experimental tunneling ionization yield of helium have practically confirmed focusing to ultrarelativistic intensities of over 1020 W/cm2 within 16% accuracy.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.60.Fc Modulation, tuning, and mode locking
42.79.Bh Lenses, prisms and mirrors

Two-color pump-probe system broadly tunable over the visible and the near infrared with sub-30 fs temporal resolution

Cristian Manzoni, Dario Polli, and Giulio Cerullo

Rev. Sci. Instrum. 77, 023103 (2006); http://dx.doi.org/10.1063/1.2167128 (9 pages) | Cited 40 times

Online Publication Date: 14 February 2006

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We describe an ultrafast spectroscopy system based on two synchronized noncollinear optical parametric amplifiers (NOPAs). Each NOPA can be independently configured to generate ultrabroadband sub-10 fs visible pulses, tunable 15 fs visible pulses (500–720 nm), tunable 15–30 fs near-infrared pulses (900–1500 nm), and 15–20 fs blue pulses (430–480 nm). This system enables to perform pump-probe experiments over nearly two octaves of spectrum with unprecedented temporal resolution. We present application examples highlighting the capability of this instrument to track excited-state dynamics occurring on the sub-100 fs time scale: electron transfer in polymer-fullerene blends, intersubband energy relaxation in carbon nanotubes, and internal conversion in carotenoids.
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78.47.-p Spectroscopy of solid state dynamics
07.60.Rd Visible and ultraviolet spectrometers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
42.65.Yj Optical parametric oscillators and amplifiers
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Multifunctional microscope for far-field and tip-enhanced Raman spectroscopy

Christophe Vannier, Boon-Siang Yeo, Jeremy Melanson, and Renato Zenobi

Rev. Sci. Instrum. 77, 023104 (2006); http://dx.doi.org/10.1063/1.2162449 (5 pages) | Cited 16 times

Online Publication Date: 14 February 2006

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The development of a versatile and easy-to-use instrument designed for Raman micro- and nanospectroscopy in the visible range is described in this work. An atomic force microscope, an inverted confocal microscope, and a piezostage are combined to perform an accurate and fast tip-laser alignment and to characterize large areas under the same conditions of illumination across the surface. In addition, a metallized tip is used to locally enhance the electromagnetic field and to probe the sample surface leading to in situ chemical analysis at the nanoscale. Both far-field and tip-enhanced Raman spectroscopies (TERS) have been carried out on dye molecules and on nano-objects with short exposure times. The TERS observation of tip-induced sample deformation on single-walled carbon nanotubes is also presented.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Pb Conventional optical microscopes
07.79.Lh Atomic force microscopes

Simple flow through reaction cells for in situ transmission and fluorescence x-ray-absorption spectroscopy of heterogeneous catalysts

Simon R. Bare, George E. Mickelson, Frank S. Modica, Andrzej Z. Ringwelski, and N. Yang

Rev. Sci. Instrum. 77, 023105 (2006); http://dx.doi.org/10.1063/1.2168685 (6 pages) | Cited 5 times

Online Publication Date: 14 February 2006

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We report on the design of both transmission and fluorescence x-ray-absorption spectroscopy cells suitable for in situ characterization of heterogeneous catalysts. The heart of both cells is a quartz tube used to house the catalyst sample. Both cells allow in situ x-ray-absorption fine-structure (XAFS) data to be recorded from −196 to 825 °C using a wide range of gas flows at atmospheric pressure. Excellent temperature control is demonstrated with both designs. XAFS data can be recorded over a wide x-ray energy range (2.1–29 keV). These designs are simple, robust, relatively low cost, and, moreover, are reliable and easy to operate. All of the critical components of the transmission reactor can be purchased commercially, with little machining required. The design of the fluorescence reactor requires access to a skilled glass blower.
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07.85.-m X- and γ-ray instruments
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
78.70.Dm X-ray absorption spectra

Large atom number Bose-Einstein condensate machines

Erik W. Streed, Ananth P. Chikkatur, Todd L. Gustavson, Micah Boyd, Yoshio Torii, Dominik Schneble, Gretchen K. Campbell, David E. Pritchard, and Wolfgang Ketterle

Rev. Sci. Instrum. 77, 023106 (2006); http://dx.doi.org/10.1063/1.2163977 (13 pages) | Cited 4 times

Online Publication Date: 24 February 2006

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We describe experimental setups for producing large Bose-Einstein condensates of math and math. In both, a high-flux thermal atomic beam is decelerated by a Zeeman slower and is then captured and cooled in a magneto-optical trap. The atoms are then transferred into a cloverleaf-style Ioffe-Pritchard magnetic trap and cooled to quantum degeneracy with radio-frequency-induced forced evaporation. Typical condensates contain 20×106 atoms. We discuss the similarities and differences between the techniques used for producing large math and math condensates in the context of nearly identical setups.
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03.75.Nt Other Bose-Einstein condensation phenomena
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
32.60.+i Zeeman and Stark effects

Photoelastic modulated imaging ellipsometry by stroboscopic illumination technique

Chien-Yuan Han and Yu-Faye Chao

Rev. Sci. Instrum. 77, 023107 (2006); http://dx.doi.org/10.1063/1.2173027 (5 pages) | Cited 6 times

Online Publication Date: 24 February 2006

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A novel stroboscopic illumination technique is applied in a photoelastic modulated (PEM) ellipsometry to conquer the slow imaging processing of charge-coupled device camera system and form a fast imaging ellipsometry. The synchronized ultrastable short pulse is used to freeze the intensity variation of the PEM modulated signal. The temporal phase is calibrated with respect to the time reference of PEM. The laser diode is modulated by a programable pulse generator for triggering four short pulses at their specific temporal phase angle. The two-dimensional (2D) ellipsometric parameters can be deduced from those recorded four images. Therefore, the 2D thickness profile of a patterned sample can be measured; a static patterned SiO2 thin film on silicon substrate and the drainage behavior of matching oil on silicon wafer were studied by this imaging ellipsometry.
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07.60.Fs Polarimeters and ellipsometers
81.70.Fy Nondestructive testing: optical methods
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Blue light-emitting diode-based, enhanced resonant excitation of longitudinal acoustic modes in a closed pipe with application to NO2

Guillermo D. Santiago, Martín G. González, Alejandro L. Peuriot, Francisco González, and Verónica B. Slezak

Rev. Sci. Instrum. 77, 023108 (2006); http://dx.doi.org/10.1063/1.2173031 (3 pages) | Cited 6 times

Online Publication Date: 24 February 2006

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We present a new, very compact resonant photoacoustic system based on a simple closed pipe, transversally illuminated by an array of blue light-emitting diodes uniformly distributed along the tube to produce an acoustic signal from NO2–N2 samples. The illumination is modulated in a particular way as to produce amplification of the acoustic resonance corresponding to the second longitudinal mode. The linearity of the system for NO2 trace detection is studied. This arrangement provides a simple, compact, and cheap setup, useful for both measuring emissions from diesel engines and teaching photoacoustic spectroscopy in gases.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.60.Jb Light-emitting devices
85.60.Gz Photodetectors (including infrared and CCD detectors)
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Beam dynamics in a spectrometer for the polarized positron production experiment

Yuri K. Batygin

Rev. Sci. Instrum. 77, 023301 (2006); http://dx.doi.org/10.1063/1.2168676 (5 pages)

Online Publication Date: 14 February 2006

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The proposed experiment E-166 at SLAC is designed to demonstrate the possibility of producing longitudinally polarized positrons from circularly polarized photons to be used in future linear collider. The experimental setup utilizes a low emittance 50 GeV electron beam passing through a helical undulator in the final focus test beam line of the SLAC accelerator. Circularly polarized photons generated by the electron beam in the undulator hit a target and produce electron-positron pairs. The purpose of the post-target spectrometer is to select the positron beam and to deliver it to a polarimeter while keeping the positron beam polarization as high as possible. This article analyzes positron transmission and polarization in the E-166 spectrometer experiment. The positron transmission has a maximum value of 7% for a positron beam energy of 5.5 MeV, while positron polarization is approximately 60%.
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29.27.Bd Beam dynamics; collective effects and instabilities
41.75.Fr Electron and positron beams
29.25.Bx Electron sources
07.77.Ka Charged-particle beam sources and detectors
41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles
29.30.-h Spectrometers and spectroscopic techniques

Low energy electron diffraction using an electronic delay-line detector

D. Human, X. F. Hu, C. J. Hirschmugl, J. Ociepa, G. Hall, O. Jagutzki, and K. Ullmann-Pfleger

Rev. Sci. Instrum. 77, 023302 (2006); http://dx.doi.org/10.1063/1.2170078 (8 pages) | Cited 1 time

Online Publication Date: 14 February 2006

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A low energy electron diffraction (LEED) instrument incorporating a delay line detector has been constructed to rapidly collect high-quality digital LEED images with low total electron exposures. The system uses a position-sensitive pulse-counting detector with high bias current microchannel plates. This delay-line detector combined with a femtoampere electron gun offers a wide range of flexibility, with electron dosing currents ranging from 0.15 pA to 0.3 fA. Using the highest current setting and collecting 1×106 counts per image, individual LEED images can be completed in 4 s with an acquisition rate of 250 kHz and a total electron exposure of 5×106 electrons. Under the latter conditions, images can be collected in 20 min with an acquisition rate of 1 kHz with a total electron exposure of 2×106 electrons. An angular width of 0.13° at 108 eV is demonstrated, which means that domain sizes as large as 600 Å can be resolved, depending on the surface quality of the crystal. The system electronics collect 2048×2048 pixel images with a spatial resolution of about 75 μm. The dynamic range of this system is 32 bits/pixel (limited only by physical memory). The construction of the detector results in a “plus”-shaped artifact, which requires that, for a given sample orientation, two images be taken at a relative angle of 45°. Identical current-voltage curves from an MgO(111)1×1 H terminated sample, taken during several hours of exposure to the low current electron beam, demonstrate minimal electron induced H desorption.
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61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
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A new atomic force microscope probe with force sensing integrated readout and active tip

A. G. Onaran, M. Balantekin, W. Lee, W. L. Hughes, B. A. Buchine, R. O. Guldiken, Z. Parlak, C. F. Quate, and F. L. Degertekin

Rev. Sci. Instrum. 77, 023501 (2006); http://dx.doi.org/10.1063/1.2166469 (7 pages) | Cited 39 times

Online Publication Date: 9 February 2006

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We introduce a novel probe structure for the atomic force microscope. The probe has a sharp tip placed on a micromachined membrane with an integrated displacement sensor, a diffraction-based optical interferometer. We use this probe in a microscope to directly measure the transient interaction forces between the probe tip and the sample when operating in a dynamic mode. We form images related to viscoelasticity and adhesion of the samples by recording salient features of individual tap signals. We also produce tapping mode images of sample topography an order of magnitude faster than current probe microscopes using an integrated electrostatic actuator to move the probe tip. We envision a broad range of applications for this device that range from life sciences to microelectronics.
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07.79.Lh Atomic force microscopes
07.10.Pz Instruments for strain, force, and torque
07.60.Ly Interferometers
07.10.Cm Micromechanical devices and systems

Magnetic diagnostic system of the DIII-D tokamak

E. J. Strait

Rev. Sci. Instrum. 77, 023502 (2006); http://dx.doi.org/10.1063/1.2166493 (14 pages) | Cited 17 times

Online Publication Date: 9 February 2006

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External measurements of the magnetic field surrounding a hot, magnetically confined plasma yield important information about the state of the plasma, since the external field is generated in part by electric currents within the plasma itself. Therefore, magnetic diagnostics are an essential part of both the operation and the physics experiments in tokamaks and other magnetic confinement devices. The magnetic diagnostic system of the DIII-D tokamak includes approximately 250 inductive sensors of various types: axisymmetric poloidal flux loops, diamagnetic-flux loops, magnetic probes and saddle loops for the measurement of local magnetic field, and Rogowski loops for the measurement of coil currents and plasma current. The primary uses of the data include plasma shape and position control with a real-time digital control system, postdischarge equilibrium reconstruction, spectrum analysis in time and space of plasma instabilities, and direct feedback control of slowly growing instabilities. The sensors, instrumentation, calibration, applications, and operating experience are described.
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52.70.Ds Electric and magnetic measurements
52.55.Fa Tokamaks, spherical tokamaks
52.25.Fi Transport properties
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
07.05.Dz Control systems

Improved signal analysis for the calibration of the motional Stark effect diagnostic

Yuejiang Shi

Rev. Sci. Instrum. 77, 023503 (2006); http://dx.doi.org/10.1063/1.2166667 (8 pages) | Cited 1 time

Online Publication Date: 9 February 2006

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A Stokes vector and Mueller matrix formalism are adopted to model the optical train of the motional stark effect (MSE) system. The method to find all four elements of Stokes vectors and optical parameters of MSE system is presented in this article. A new fitting model for MSE calibration is discussed. A method for the measurement of offset angle of MSE is also presented. The nonideal effects of the background unpolarized and polarized light of non-Stark effect are analyzed.
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07.60.-j Optical instruments and equipment
06.20.fb Standards and calibration
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Investigation of the disturbance of a Langmuir probe and its influence on measurement results

C. Brandt, H. Testrich, R. Kozakov, and C. Wilke

Rev. Sci. Instrum. 77, 023504 (2006); http://dx.doi.org/10.1063/1.2166468 (5 pages) | Cited 3 times

Online Publication Date: 14 February 2006

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Measurements of plasma parameters by Langmuir probes are influenced by the probe system itself. This article considers the deviation of plasma parameters determined by probe measurements from those in the undisturbed plasma. For this reason the particle density of the excited atoms of a neon plasma in the very vicinity of the probe is compared with the particle density in the undisturbed case. The densities of the excited metastable 1s5 level were measured by laser absorption spectroscopy. By solving the plasma balance equations the deviation of the electron density and the deviation of the electric field could be deduced.
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52.70.Ds Electric and magnetic measurements
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.-b Plasma properties

Radiation hardness of a polycrystalline chemical-vapor-deposited diamond detector irradiated with 14 MeV neutrons

M. Angelone, M. Pillon, A. Balducci, M. Marinelli, E. Milani, M. E. Morgada, G. Pucella, A. Tucciarone, G. Verona-Rinati, Kentaro Ochiai, and Takeo Nishitani

Rev. Sci. Instrum. 77, 023505 (2006); http://dx.doi.org/10.1063/1.2167130 (7 pages) | Cited 3 times

Online Publication Date: 14 February 2006

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Chemical-vapor-deposited (CVD) diamond films are considered as neutron detectors for nuclear fusion devices because of their radiation hardness. Data about the radiation hardness of polycrystalline CVD diamond films exposed to 14 MeV neutron are missing in literature so the actual capability of CVD diamond detectors to withstand fusion device conditions must be truly demonstrated. In this work a polycrystalline CVD diamond detector, 101 μm thick, was irradiated for the first time with 14 MeV neutrons produced by the Fusion Neutron Source of the Japan Atomic Energy Research Institute with the goal to study its radiation hardness. The 14 MeV neutron fluence was 8×1014 n/cm2. The film performances were studied before and after the 14 MeV neutron irradiation by using 5.5 MeV α from math source, both in the pumped and the “as-grown” state. A comparison with previous measurements performed in more soft neutron spectra (mean neutron energy of 1–2 MeV) is reported pointing out the more damaging effects of the 14 MeV neutrons. It was found that annealing at 500 °C and redeposition of the gold contact followed by a proper pumping procedure will restore more than 70% the initial working conditions of the irradiated detector. An analysis of the neutron field expected in the neutron camera of the International Thermonuclear Reactor fusion tokamak was also performed, showing the capability of CVD diamond detector to withstand the 14 MeV neutron fluence expected in about one year of operation.
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29.40.Wk Solid-state detectors
61.80.Hg Neutron radiation effects
61.72.Cc Kinetics of defect formation and annealing

Fast singular value decomposition combined maximum entropy method for plasma tomography

Junghee Kim and W. Choe

Rev. Sci. Instrum. 77, 023506 (2006); http://dx.doi.org/10.1063/1.2169489 (6 pages)

Online Publication Date: 24 February 2006

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The maximum entropy method (MEM) is a widely used reconstruction algorithm in plasma physics. Drawbacks of the conventional MEM are its heavy time-consuming process and possible generation of noisy reconstruction results. In this article, a modified maximum entropy algorithm is described which speeds up the calculation and shows better noise handling capability. Similar to the rapid minimum Fisher information method, the modified maximum entropy algorithm uses simple matrix operations instead of treating a fully nonlinear problem. The preprocess for rapid tomographic calculation is based on the vector operations and the singular value decomposition (SVD). The initial guess of the sought-for emissivity is calculated by SVD and this helped reconstruction about ten times faster than the conventional MEM. Therefore, the developed fast MEM can be used for intershot tomographic analyses of fusion plasmas.
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07.05.Pj Image processing
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
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Atomic force microscopy compatible device for stretching cells and adsorbed proteins

K. L. De Jong, H. C. MacLeod, P. R. Norton, N. O. Petersen, and M. F. Jasnin

Rev. Sci. Instrum. 77, 023701 (2006); http://dx.doi.org/10.1063/1.2163974 (6 pages)

Online Publication Date: 9 February 2006

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A device that we term a “microrack” was designed to provide a means to stretch cells and proteins and to permit the measurement of any changes in adhesion forces that might occur as a result of the strain, with an atomic force microscope. The device requires an elastic material that allows adsorption of proteins and attachment of cells. The elastomer polydimethylsiloxane (PDMS) was chosen, and its suitability for short-term cell studies was tested by comparing cell morphology and fiber distribution on PDMS with cells grown on glass, a conventional substrate for cell study. Atomic force microscopy (AFM) images and section analysis of beads and scrape marks on the PDMS surface before and after stretching indicate that the microrack can provide up to 21%–29% deformation of PDMS. AFM images of cells grown on PDMS show that material attached to the surface is also affected by stretching of the microrack. The rupture of the cell after stretching and rippling of the cell under compression can be attributed to the fixation treatment, but indicates that the cell morphology is significantly affected by the movement of the substrate on the microrack.
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87.64.Dz Scanning tunneling and atomic force microscopy
87.80.-y Biophysical techniques (research methods)
87.17.-d Cell processes
87.14.E- Proteins

Thin-foil magnetic force system for high-numerical-aperture microscopy

J. K. Fisher, J. Cribb, K. V. Desai, L. Vicci, B. Wilde, K. Keller, R. M. Taylor, J. Haase, K. Bloom, E. Timothy O’Brien, and R. Superfine

Rev. Sci. Instrum. 77, 023702 (2006); http://dx.doi.org/10.1063/1.2166509 (9 pages) | Cited 16 times

Online Publication Date: 14 February 2006

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Forces play a key role in a wide range of biological phenomena from single-protein conformational dynamics to transcription and cell division, to name a few. The majority of existing microbiological force application methods can be divided into two categories: those that can apply relatively high forces through the use of a physical connection to a probe and those that apply smaller forces with a detached probe. Existing magnetic manipulators utilizing high fields and high field gradients have been able to reduce this gap in maximum applicable force, but the size of such devices has limited their use in applications where high force and high-numerical-aperture (NA) microscopy must be combined. We have developed a magnetic manipulation system that is capable of applying forces in excess of 700 pN on a 1 μm paramagnetic particle and 13 nN on a 4.5 μm paramagnetic particle, forces over the full 4π sr, and a bandwidth in excess of 3 kHz while remaining compatible with a commercially available high-NA microscope objective. Our system design separates the pole tips from the flux coils so that the magnetic-field geometry at the sample is determined by removable thin-foil pole plates, allowing easy change from experiment to experiment. In addition, we have combined the magnetic manipulator with a feedback-enhanced, high-resolution (2.4 nm), high-bandwidth (10 kHz), long-range (100 μm xyz range) laser tracking system. We demonstrate the usefulness of this system in a study of the role of forces in higher-order chromosome structure and function.
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87.64.Dz Scanning tunneling and atomic force microscopy
87.16.Sr Chromosomes, histones

Scanning thermal-conductivity microscope

Dror Sarid, Brendan McCarthy, and Ranjan Grover

Rev. Sci. Instrum. 77, 023703 (2006); http://dx.doi.org/10.1063/1.2168391 (7 pages) | Cited 2 times

Online Publication Date: 14 February 2006

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This article describes a novel implementation of an atomic force microscope that can map thermal-conductivity features across a sample with a high spatial resolution. The microscope employs a single-sided, metal-coated cantilever, which acts as a bimetallic strip together with a heating laser whose beam is focused on the cantilever’s free end, on the opposite side of its tip. Subtracting the topography obtained by the unheated and heated cantilevers yields a map of thermal conductivity across the surface of a sample. The article presents (a) the theory of operation of the microscope and (b) the experimental results obtained on a silicon sample with oxide features, showing good agreement between the two.
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07.79.Lh Atomic force microscopes

Compact variable-temperature magnetic force microscope with optical access and lateral cantilever positioning

Casey Israel, Changbae Hyun, Alex de Lozanne, Soohyon Phark, and Z. G. Khim

Rev. Sci. Instrum. 77, 023704 (2006); http://dx.doi.org/10.1063/1.2168681 (6 pages) | Cited 9 times

Online Publication Date: 14 February 2006

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We describe a compact design for a variable-temperature magnetic force microscope that incorporates a novel mechanical device for the lateral positioning of a piezoresistive cantilever under the guidance of an external optical microscope. The small size of the instrument makes it possible to perform low-temperature experiments by inserting the probe directly into a liquid-helium storage Dewar or into any open or closed liquid-nitrogen container. Besides convenience, this also means that the cycle time for exchanging tips and∕or samples can be as short as 4 h, including warm-up and cooldown. The probe is long enough to reach the middle of an 8 T superconducting magnet. We present the details of this design and show some results.
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07.79.Pk Magnetic force microscopes

Demonstration of low-temperature atomic force microscope with atomic resolution using piezoresistive cantilevers

Ichiro Shiraki, Yutaka Miyatake, Toshihiko Nagamura, and Kazushi Miki

Rev. Sci. Instrum. 77, 023705 (2006); http://dx.doi.org/10.1063/1.2169469 (4 pages) | Cited 4 times

Online Publication Date: 14 February 2006

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Compared to current optical-lever methods adopted in atomic force microscopes, nonoptical methods such as piezoresistive methods and quartz fork methods can be more advantageous due to their smaller installation size and the lack of electromagnetic effects from laser light during electrical conductivity experiments. As a technological demonstration of nonoptical methods, a low-temperature atomic force microscope using piezoresistive cantilevers was developed and operated at liquid-math temperatures (5 K). The cantilever and sample can be transferred from atmosphere to the microscope head operating at low temperatures. Both contact mode and noncontact mode were used for testing the system while carrying out atomic resolution studies on clean Si(111) and clean Si(100) surfaces.
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07.79.Lh Atomic force microscopes
68.37.Ps Atomic force microscopy (AFM)
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Apparatus for high-resolution microwave spectroscopy in strong magnetic fields

W. A. Huttema, B. Morgan, P. J. Turner, W. N. Hardy, Xiaoqing Zhou, D. A. Bonn, Ruixing Liang, and D. M. Broun

Rev. Sci. Instrum. 77, 023901 (2006); http://dx.doi.org/10.1063/1.2167127 (9 pages) | Cited 6 times

Online Publication Date: 14 February 2006

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We have developed a low-temperature, high-resolution microwave surface-impedance probe that uses cavity perturbation of dielectric resonators and is able to operate in high static magnetic field. This method has sufficient sensitivity to resolve the microwave absorption of submillimeter-sized superconducting samples. The resonators are constructed from high-permittivity single-crystal rutile (TiO2) and have quality factors in excess of 106. Resonators with such high performance have traditionally required the use of superconducting materials, making them incompatible with large magnetic fields and subject to problems associated with aging and power-dependent response. Rutile resonators avoid these problems while retaining comparable sensitivity to surface impedance. Our cylindrical rutile resonators have a hollow bore and are excited in TE01(n−δ) modes, providing homogeneous microwave fields at the center of the resonator where the sample is positioned. Using a sapphire hot-finger technique, measurements can be made at sample temperatures in the range of 1.1–200 K, while the probe itself remains immersed in a liquid-helium bath at 4.2 K. The novel apparatus described in this article is an extremely robust and versatile system for microwave spectroscopy, integrating several important features into a single system. These include operation at high magnetic fields, multiple measurement frequencies between 2.64 and 14.0 GHz in a single resonator, excellent frequency stability, with typical drifts <1 Hz/h, the ability to withdraw the sample from the resonator for background calibration, and a small pot of liquid helium separated from the external bath that provides a sample base temperature of 1.1 K. Without modification, this system can be employed for dielectric spectroscopy, electron-spin resonance, and other microwave spectroscopies.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques

Localized spin-wave excitation by the evanescent microwave scanning probe

F. Sakran, M. Golosovsky, D. Davidov, and P. Monod

Rev. Sci. Instrum. 77, 023902 (2006); http://dx.doi.org/10.1063/1.2167131 (5 pages) | Cited 2 times

Online Publication Date: 14 February 2006

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We report a technique for the local contactless spin-wave excitation using the evanescent microwave scanning probe. Our probe is based on a dielectric resonator with the thin slit aperture. It operates at 8.8 GHz, has a spatial resolution of 10–100 μm, and may be operated in the parallel and in the perpendicular magnetic field. The measurements can be performed in contact mode or by scanning the sample at constant probe-sample separation. Using 120–150 nm thick Permalloy films on a glass substrate as test samples, we show how our technique can be used for thickness measurements of thin magnetic films and for the mapping of their magnetic properties, such as magnetization and surface anisotropy.
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07.79.-v Scanning probe microscopes and components
75.30.Ds Spin waves
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Gw Magnetic anisotropy
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)

New design of fiber-optic reflectometer for determining the phase boundary of multicomponent fluid mixtures at high pressures and high temperatures

Weize Wu, Jie Ke, and Martyn Poliakoff

Rev. Sci. Instrum. 77, 023903 (2006); http://dx.doi.org/10.1063/1.2168390 (4 pages) | Cited 3 times

Online Publication Date: 14 February 2006

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A dynamic synthetic method based on an optic fiber sensor has been developed to measure phase boundaries of multicomponent fluid at high temperatures >300 °C and pressures >30 MPa. The breakthrough has been the design of the equilibrium cell containing the optic fiber, which gives highly reproducible signals for the phase transition. We demonstrate that this method can clearly distinguish between dew points and bubble points in the phase transitions of mixtures. Overall, the method is characterized by speed, simplicity, high pressures, and high temperatures.
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42.81.Pa Sensors, gyros
07.60.Hv Refractometers and reflectometers
07.60.Vg Fiber-optic instruments
42.15.Eq Optical system design
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