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Jan 2008

Volume 79, Issue 1, Articles (01xxxx)

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Rev. Sci. Instrum. 79, 011101 (2008); http://dx.doi.org/10.1063/1.2823259 (16 pages)

S. S. Medley, A. J. H. Donné, R. Kaita, A. I. Kislyakov, M. P. Petrov, and A. L. Roquemore
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Invited Review Article: Contemporary instrumentation and application of charge exchange neutral particle diagnostics in magnetic fusion energy experiments

S. S. Medley, A. J. H. Donné, R. Kaita, A. I. Kislyakov, M. P. Petrov, and A. L. Roquemore

Rev. Sci. Instrum. 79, 011101 (2008); http://dx.doi.org/10.1063/1.2823259 (16 pages) | Cited 4 times

Online Publication Date: 23 January 2008

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An overview of the developments postcirca 1980s in the instrumentation and application of charge exchange neutral particle diagnostics on magnetic fusion energy experiments is presented. First, spectrometers that employ only electric fields and hence provide ion energy resolution but not mass resolution are discussed. Next, spectrometers that use various geometrical combinations of both electric and magnetic fields to provide both energy and mass resolutions are reviewed. Finally, neutral particle diagnostics based on utilization of time-of-flight techniques are presented.
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52.70.-m Plasma diagnostic techniques and instrumentation
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Measurement of temperature of laser cooled atoms by one-dimensional expansion in a magneto-optical trap

S. Pradhan and B. N. Jagatap

Rev. Sci. Instrum. 79, 013101 (2008); http://dx.doi.org/10.1063/1.2827517 (4 pages) | Cited 3 times

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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37.10.Gh Atom traps and guides
32.60.+i Zeeman and Stark effects
32.50.+d Fluorescence, phosphorescence (including quenching)
32.80.-t Photoionization and excitation

A high pressure cell for dynamic light scattering up to 2 kbars with conservation of plane of polarization

G. Meier and H. Kriegs

Rev. Sci. Instrum. 79, 013102 (2008); http://dx.doi.org/10.1063/1.2827137 (5 pages) | Cited 2 times

Online Publication Date: 7 January 2008

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We report on a high pressure cell with six optical windows which can be used up to 2 kbars for laser light scattering applications at scattering angles of 45°, 90°, and 135° of liquid samples in a temperature range between −20 and 150 °C. The pressure transmitting medium is compressed nitrogen. The window material used is SF57 NSK, a glass with an extremely low stress optical coefficient in the order of about 10−5 which allows thus to maintain the plane of polarization even under the action of high pressure. In order to demonstrate the functioning of the cell we show Rayleigh-Brillouin spectra of poly(methylphenylsiloxane) at different polarizations and pressures.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
42.79.Ci Filters, zone plates, and polarizers
42.70.Ce Glasses, quartz
42.70.Jk Polymers and organics
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Time-resolved scanning system for double reflectance and transmittance fluorescence imaging of diffusive media

Marco Brambilla, Lorenzo Spinelli, Antonio Pifferi, Alessandro Torricelli, and Rinaldo Cubeddu

Rev. Sci. Instrum. 79, 013103 (2008); http://dx.doi.org/10.1063/1.2828054 (9 pages) | Cited 8 times

Online Publication Date: 10 January 2008

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In this work we present a novel diffuse fluorescence imaging system, based on time-resolved two-wavelength double reflectance and transmittance setup for slab geometry samples. We describe the hardware setup, showing its compactness and versatility and show the results on preliminary measurements on phantoms. We fully assessed the performances and the dynamic ranges of the system. We validated its ability of recovering the optical properties of the bulk medium, for samples with scattering and absorption coefficients similar to those of biological tissues and with thicknesses of about 2 cm. Moreover we assess the linearity of the recorded signals against the fluorophore concentration, when it is homogeneously diffused in the phantom or concentrated inside a sealed inclusion. In both cases we observe again a fairly good linearity, over three orders of magnitude, from 10−8M to 10−5M. With the fluorescent inclusion we were also able to assess the imaging capabilities of the system, in terms of spatial resolution, which we appraise in about 3 mm, and in terms of imaging sensitivity (the smallest quantity of fluorescent dye distinguishable from the homogeneous background), settled to 200 fmol. Since the recorded data are time resolved, we could also estimate the dye fluorescence lifetime and build early and late time gate images. We finally discuss some of the criticalities of the proposed system and the developments we are currently carrying on in order to adapt it for in vivo measurements.
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87.15.mq Luminescence
87.57.-s Medical imaging
87.85.Pq Biomedical imaging
87.64.kv Fluorescence

Phase-locked laser system for use in atomic coherence experiments

Alberto M. Marino and C. R. Stroud, Jr.

Rev. Sci. Instrum. 79, 013104 (2008); http://dx.doi.org/10.1063/1.2823330 (8 pages) | Cited 6 times

Online Publication Date: 11 January 2008

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We describe a phase-coherent laser system designed for use in experiments involving coherently prepared atomic media. We implement a simple technique based on a sample-and-hold circuit together with a reset of the integrating electronics that makes it possible to scan continuously the relative frequency between the lasers of over tens of gigahertz while keeping them phase locked. The system consists of three external-cavity diode lasers operating around 795 nm. A low-power laser serves as a frequency reference for two high-power lasers which are phased locked with an optical phase-locked loop. We measured the residual phase noise of the system to be less than 0.04 rad2. In order to show the application of the system towards atomic coherence experiments, we used it to implement electromagnetically induced transparency in a rubidium vapor cell and obtained a reduction in the absorption coefficient of 92%.
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42.60.Fc Modulation, tuning, and mode locking
42.25.Kb Coherence
42.55.Px Semiconductor lasers; laser diodes
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency

An apparatus for simultaneous thermodynamic and optical measurements, with large temperature excursions

A. Giannasi, M. Celli, F. Grazzi, L. Ulivi, and M. Zoppi

Rev. Sci. Instrum. 79, 013105 (2008); http://dx.doi.org/10.1063/1.2830939 (5 pages) | Cited 4 times

Online Publication Date: 16 January 2008

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We report the design and realization of an integrated system for measuring, at the same time, the thermodynamic and spectroscopic features of nanoporous materials interesting for hydrogen storage purposes. The whole investigation cycle, from thermal activation to the actual investigation of uptake and release of hydrogen, is carried out in the same vacuum tight vessel, equipped with an optical window, whose temperature can range between 10 and 750 K, up to a maximum pressure of 50 bars. The system has been designed to investigate properties of carbon nanotubes but its use can be extended to any kind of nanoporous sample such as, for example, carbon nanofibers, zeolytes, metal organic frameworks, and similar materials.
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51.30.+i Thermodynamic properties, equations of state
61.43.Gt Powders, porous materials
84.60.-h Direct energy conversion and storage

Wide band focusing x-ray spectrograph with spatial resolution

S. A. Pikuz, J. D. Douglass, T. A. Shelkovenko, D. B. Sinars, and D. A. Hammer

Rev. Sci. Instrum. 79, 013106 (2008); http://dx.doi.org/10.1063/1.2834834 (7 pages) | Cited 9 times

Online Publication Date: 18 January 2008

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A new, wide spectral bandwidth x-ray spectrograph, the wide-bandwidth focusing spectrograph with spatial resolution (WB-FSSR), based on spherically bent mica crystals, is described. The wide bandwidth is achieved by combining three crystals to form a large aperture dispersive element. Since the WB-FSSR covers a wide spectral band, it is very convenient for application as a routine diagnostic tool in experiments in which the desired spectral coverage is different from one test to the next. The WB-FSSR has been tested in imploding wire-array experiments on a 1 MA pulsed power machine, and x-ray spectra were recorded in the 1–20 Å spectral band using different orders of mica crystal reflection. Using a two mirror-symmetrically placed WB-FSSR configuration, it was also possible to distinguish between a real spectral shift and a shift of recorded spectral lines caused by the spatial distribution of the radiating plasma. A spectral resolution of about 2000 was demonstrated and a spatial resolution of ∼ 100 μm was achieved in the spectral band of 5–10 Å in second order of mica reflection. A simple method of numerical analysis of spectrograph capability is proposed.
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07.85.Nc X-ray and γ-ray spectrometers
52.70.-m Plasma diagnostic techniques and instrumentation
61.05.C- X-ray diffraction and scattering

Ultrasensitive ultraviolet-visible 20 fs absorption spectroscopy of low vapor pressure molecules in the gas phase

C. Schriever, S. Lochbrunner, E. Riedle, and D. J. Nesbitt

Rev. Sci. Instrum. 79, 013107 (2008); http://dx.doi.org/10.1063/1.2834877 (9 pages) | Cited 6 times

Online Publication Date: 24 January 2008

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We describe an ultrasensitive pump-probe spectrometer for transient absorption measurements in the gas phase and in solution. The tunable UV pump and the visible (450–740 nm) probe pulses are generated by two independently tunable noncollinear optical parametric amplifiers, providing a temporal resolution of 20 fs. A homebuilt low gain photodetector is used to accommodate strong probe pulses with a shot noise significantly lower than the overall measurement noise. A matched digitizing scheme for single shot analysis of the light pulses at kilohertz repetition rates that minimizes the electronic noise contributions to the transient absorption signal is developed. The data processing scheme is optimized to yield best suppression of the laser excess noise and thereby transient absorbance changes down to 1.1×10−6 can be resolved. A collinear focusing geometry optimized for a 50 mm interaction length combined with a heatable gas cell allows us to perform measurements on substances with low vapor pressures, e.g., on medium sized molecules which are crystalline at room temperature. As an application example highlighting the capability of this instrument, we present the direct time-domain observation of the ultrafast excited state intramolecular proton transfer of 2-(2′-hydroxyphenyl)benzothiazole in the gas phase. We are able to compare the resulting dynamics in the gas phase and in solution with a temporal precision of better than 5 fs.
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51.70.+f Optical and dielectric properties
33.20.Lg Ultraviolet spectra
33.20.Kf Visible spectra

Precision polarimetry with real-time mitigation of optical-window birefringence

B. K. Park, A. O. Sushkov, and D. Budker

Rev. Sci. Instrum. 79, 013108 (2008); http://dx.doi.org/10.1063/1.2835902 (5 pages) | Cited 1 time

Online Publication Date: 30 January 2008

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Optical-window birefringence is frequently a major obstacle in experiments measuring changes in the polarization state of light traversing a sample under investigation. It can contribute a signal indistinguishable from that due to the sample and complicate the analysis. Here, we explore a method to measure and compensate for the birefringence of an optical window using the reflection from the last optical surface before the sample. We demonstrate that this arrangement can cancel out false signals due to the optical-window birefringence-induced ellipticity drift to about 1%, for the values of total ellipticity less than 0.25 rad.
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07.60.Fs Polarimeters and ellipsometers
42.25.Lc Birefringence
42.79.Ci Filters, zone plates, and polarizers

A homemade high-resolution orthogonal-injection time-of-flight mass spectrometer with a heated capillary inlet

Changjuan Guo, Zhengxu Huang, Wei Gao, Huiqing Nian, Huayong Chen, Junguo Dong, Guoying Shen, Jiamo Fu, and Zhen Zhou

Rev. Sci. Instrum. 79, 013109 (2008); http://dx.doi.org/10.1063/1.2832334 (8 pages) | Cited 1 time

Online Publication Date: 31 January 2008

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We describe a homemade high-resolution orthogonal-injection time-of-flight (O-TOF) mass spectrometer combing a heated capillary inlet. The O-TOF uses a heated capillary tube combined with a radio-frequency only quadrupole (rf-only quadrupole) as an interface to help the ion transmission from the atmospheric pressure to the low-pressure regions. The principle, configuration of the O-TOF, and the performance of the instrument are introduced in this paper. With electrospray ion source, the performances of the mass resolution, the sensitivity, the mass range, and the mass accuracy are described. We also include our results obtained by coupling atmospheric pressure matrix-assisted laser deporption ionization with this instrument.
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07.75.+h Mass spectrometers
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Circular one-dimensional position-sensitive time-of-flight microchannel plate detector using resistive anode for space plasma measurements

Shoichiro Yokota and Yoshifumi Saito

Rev. Sci. Instrum. 79, 013301 (2008); http://dx.doi.org/10.1063/1.2829881 (6 pages) | Cited 1 time

Online Publication Date: 16 January 2008

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We have developed circular one-dimensional position-sensitive time-of-flight microchannel plate (MCP) detector for space plasma measurements. The MCP detector is equipped with a 354.375° resistive anode and a grid anode for obtaining position and timing signals simultaneously from one start event. The resistive anode provides high-resolution and continuous position sensing with two electronic channels alone. The grid anode generates start signals with pulse width of 1 ns for time-of-flight measurements. The resistive anode is formed on an alumina substrate which is installed behind the output side of the MCP plates. The grid anode is installed between the MCP plates and the resistive anode for the simultaneous detection of position and start signals. Stop signals are obtained from stop events by a center anode formed on the alumina substrate behind the MCP plates. On the basis of the test experiments, we have evaluated that the MCP detector functionally deals with the position and timing signals.
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93.85.-q Instruments and techniques for geophysical research: Exploration geophysics
94.80.+g Instrumentation for space plasma physics, ionosphere, and magnetosphere
85.60.Ha Photomultipliers; phototubes and photocathodes

An ion thruster internal discharge chamber electrostatic probe diagnostic technique using a high-speed probe positioning system

Daniel A. Herman and Alec D. Gallimore

Rev. Sci. Instrum. 79, 013302 (2008); http://dx.doi.org/10.1063/1.2800772 (10 pages) | Cited 1 time

Online Publication Date: 17 January 2008

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Extensive resources have been allocated to diagnose and minimize lifetime-limiting factors in gridded ion thrusters. While most of this effort has focused on grid erosion, results from wear tests indicate that discharge cathode erosion may also play an important role in limiting the lifetime of ring-cusp ion thrusters proposed for future large flagship missions. The detailed characterization of the near-cathode discharge plasma is essential for mitigating discharge cathode erosion. However, severe difficulty is encountered when attempting to measure internal discharge plasma parameters during thruster operation with conventional probing techniques. These difficulties stem from the high-voltage, high-density discharge cathode plume, which is a hostile environment for probes. A method for interrogating the discharge chamber plasma of a working ion thruster over a two-dimensional grid is demonstrated. The high-speed axial reciprocating probe positioning system is used to minimize thruster perturbation during probe insertion and to reduce heating of the probe. Electrostatic probe measurements from a symmetric double Langmuir probe are presented over a two-dimensional spatial array in the near-discharge cathode assembly region of a 30-cm-diameter ring-cusp ion thruster. Electron temperatures, 2–5 eV, and number density contours, with a maximum of 8×1012 cm−3 on centerline, are measured. These data provide detailed electron temperature and number density contours which, when combined with plasma potential measurements, may shed light on discharge cathode erosion processes and the effect of thruster operating conditions on erosion rates.
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52.70.Ds Electric and magnetic measurements
52.75.Di Ion and plasma propulsion
52.80.Hc Glow; corona
52.25.-b Plasma properties

Analysis methodology of movable emittance-meter measurements for low energy electron beams

A. Mostacci, A. Bacci, M. Boscolo, E. Chiadroni, A. Cianchi, D. Filippetto, M. Migliorati, P. Musumeci, C. Ronsivalle, and A. R. Rossi

Rev. Sci. Instrum. 79, 013303 (2008); http://dx.doi.org/10.1063/1.2835715 (9 pages) | Cited 1 time

Online Publication Date: 25 January 2008

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The design of photoinjectors for modern free electron laser linac relies heavily on particular beam behavior in the few meters after the gun. To experimentally characterize it a movable emittance meter was proposed and built [ L. Catani et al., Rev. Sci. Instrum. 77, 093301 (2006) ] based on the beam slicing technique. This paper addresses all the aspects of analysis of the data acquired with the emittance meter and common to any slit based emittance measurement for low energy beams.
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29.27.Fh Beam characteristics
41.75.Fr Electron and positron beams
29.20.Ej Linear accelerators
41.60.Cr Free-electron lasers
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Calibration of an imaging crystal spectrometer for low x-ray energies

S. G. Lee, J. G. Bak, and M. Bitter

Rev. Sci. Instrum. 79, 013501 (2008); http://dx.doi.org/10.1063/1.2829888 (5 pages) | Cited 2 times

Online Publication Date: 10 January 2008

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An x-ray imaging crystal spectrometer was designed for the Hanbit magnetic mirror device to observe spectra of heliumlike neon at 13.4474 Å. The spectrometer consists of a spherically bent mica crystal and an x-ray sensitive vacuum charge coupled device camera. This spectrometer can provide spatially resolved spectra, making it possible to obtain profiles of the ion charge state distribution from line ratios and profiles of the plasma rotation velocity from Doppler shift measurements. The paper describes measurements of spectral resolution of this instrument for low x-ray energies.
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52.70.La X-ray and γ-ray measurements
28.52.Av Theory, design, and computerized simulation
52.55.-s Magnetic confinement and equilibrium
52.75.-d Plasma devices
52.30.-q Plasma dynamics and flow

Performance of the university of saskatchewan compact torus injector with curved acceleration electrodes

D. Liu, C. Xiao, and A. Hirose

Rev. Sci. Instrum. 79, 013502 (2008); http://dx.doi.org/10.1063/1.2828056 (6 pages)

Online Publication Date: 15 January 2008

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The first vertical compact torus (CT) injection experiment has been performed in the Saskatchewan Torus Modified (STOR-M) tokamak [ Nucl. Fusion 46, 104 (2006) ]. To increase the kinetic energy density of the injected CTs for deeper penetration, the University of Saskatchewan Compact Torus Injector (USCTI) was further modified by attaching a 90° curved inner electrode coaxial with the outer electrode. The modification extended the original CT acceleration section from 60 to 114 cm. Effects of the curved acceleration electrodes on the velocity and magnetic field of the CT are reported in this paper. It has been found that the CTs, injected horizontally, were deflected to vertical direction and CT velocity measured at the curved acceleration section increased to 180 km/s, representing a 40% increase compared with the case without the curved inner electrode in a previous experiment. At a higher acceleration bank voltage of 16 kV, this velocity increased to about 270 km/s. In addition, amplification of the CT magnetic field in the curved acceleration section has also been observed.
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52.55.Fa Tokamaks, spherical tokamaks
52.75.Fk Magnetohydrodynamic generators and thermionic convertors; plasma diodes
52.55.-s Magnetic confinement and equilibrium
52.55.Ip Spheromaks
52.80.Pi High-frequency and RF discharges

Spectroscopically pure metal vapor source for highly charged ion spectroscopy and capillary discharge soft x-ray lasers

F. G. Tomasel, V. N. Shlyaptsev, and J. J. Rocca

Rev. Sci. Instrum. 79, 013503 (2008); http://dx.doi.org/10.1063/1.2825459 (8 pages) | Cited 1 time

Online Publication Date: 17 January 2008

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We describe a compact, pulsed metal vapor source used for the production of dense plasma columns of interest for both soft x-ray laser research and spectroscopy of highly ionized plasmas. The source generates spectroscopically pure cadmium vapor jets in a room-temperature environment by rapidly heating an electrode with a capacitive discharge. In the configuration described herein, the metal vapor jet produced by the source is axially injected into a fast (up to 15 kA/ns), high current (up to 200 kA peak) capillary discharge to generate highly ionized cadmium plasma columns. Spectroscopic analysis of the discharge emission in the 12–25 nm spectral range evidences the dominance of Cu-like (CdXX) and Ni-like (CdXXI) lines and shows strong line emission at 13.2 nm from the 4d 1S0–4p 1P1 laser transition of Ni-like Cd. Hydrodynamic/atomic physics simulations performed to describe the dynamics of the plasma column and compute the optimum discharge conditions for laser amplification are discussed.
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52.75.-d Plasma devices
52.50.-b Plasma production and heating
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.65.-y Plasma simulation

Dynamic Hohlraums as x-ray sources in high-energy density science

J. F. Hansen, S. G. Glendinning, R. F. Heeter, and S. J. E. Brockington

Rev. Sci. Instrum. 79, 013504 (2008); http://dx.doi.org/10.1063/1.2804765 (7 pages) | Cited 2 times

Online Publication Date: 18 January 2008

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The first demonstration of laser driven dynamic Hohlraums (LDDH) as a spectrally smooth backlighter source for opacity and temperature measurements through absorption spectrometry of materials in local thermodynamic equilibrium at temperatures >150 eV has been made. This is a crucial temperature regime for future astrophysics and ignition fusion experiments at the nearly completed National Ignition Facility (NIF) [ E. I. Moses and C. R. Wuest, Fusion Sci. Technol. 47, 314 (2005) ] at the Lawrence Livermore National Laboratory. The new backlighter consists of a LDDH filled with either krypton or argon that implodes to create an x-ray flash. The properties of this x-ray flash have been measured in experiments at the Omega laser [ T. R. Boehly et al., Opt. Commun. 133, 495 (1997) ] at the Laboratory for Laser Energetics in Rochester, New York, satisfying all requirements imposed by future experiments: (1) the emission spectrum extends to at least 5.5 keV, well above the maximum x-ray energy ( ∼ 3.5 keV) obtained from the previously “best” opacity backlighters (uranium M-shell emission backlighters); (2) the spectrum is smooth and featureless (intensity variation <6% rms), allowing absorption spectrometry through experimental samples; (3) the emission source size is sufficiently small (<50 μm) for projection backlighting through future samples; (4) the emission is bright enough (and twice as bright as imploding hydrogen-filled capsules) for gated spectrometer measurements; (5) the emission duration is optimized ( ≈ 100 ps) for the current and future generations of spectrometers; and (6) by using only a small number of beams with limited energy and symmetry for the backlighter (10 out of 60 beams in the Omega experiments), the majority of laser beams are left available for heating sample materials to >150 eV.
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28.52.Cx Fueling, heating and ignition
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.57.-z Laser inertial confinement

High sensitivity imaging Thomson scattering for low temperature plasma

H. J. van der Meiden, R. S. Al, C. J. Barth, A. J. H. Donné, R. Engeln, W. J. Goedheer, B. de Groot, A. W. Kleyn, W. R. Koppers, N. J. Lopes Cardozo, M. J. van de Pol, P. R. Prins, D. C. Schram, A. E. Shumack, P. H. M. Smeets, et al.

Rev. Sci. Instrum. 79, 013505 (2008); http://dx.doi.org/10.1063/1.2832333 (8 pages) | Cited 23 times

Online Publication Date: 30 January 2008

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A highly sensitive imaging Thomson scattering system was developed for low temperature (0.1–10 eV) plasma applications at the Pilot-PSI linear plasma generator. The essential parts of the diagnostic are a neodymium doped yttrium aluminum garnet laser operating at the second harmonic (532 nm), a laser beam line with a unique stray light suppression system and a detection branch consisting of a Littrow spectrometer equipped with an efficient detector based on a “Generation III” image intensifier combined with an intensified charged coupled device camera. The system is capable of measuring electron density and temperature profiles of a plasma column of 30 mm in diameter with a spatial resolution of 0.6 mm and an observational error of 3% in the electron density (ne) and 6% in the electron temperature (Te) at ne = 4×1019 m−3. This is achievable at an accumulated laser input energy of 11 J (from 30 laser pulses at 10 Hz repetition frequency). The stray light contribution is below 9×1017 m−3 in electron density equivalents by the application of a unique stray light suppression system. The amount of laser energy that is required for a ne and Te measurement is 7×1020/ne J, which means that single shot measurements are possible for ne>2×1021 m−3.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.-b Plasma properties
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Polarization microscopy probe for applications in a high magnetic field

Peter J. Konijnenberg, Arndt Ziemons, Dmitri A. Molodov, and Günter Gottstein

Rev. Sci. Instrum. 79, 013701 (2008); http://dx.doi.org/10.1063/1.2829155 (3 pages) | Cited 3 times

Online Publication Date: 2 January 2008

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A microscopy probe designed for use in high field magnets is presented. It was developed to observe and continuously measure the position and shape of a magnetically driven grain boundary in a magnetically anisotropic material. The approach utilizes the anisotropy of reflectivity of visible light for orientation contrast to determine the boundary location. The major components of the system are the polarizing microscope with video camera and the sample chamber with a resistive heater for annealing at elevated temperatures up to 500 °C in an inert gas atmosphere. The results of test measurements are presented.
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61.72.Mm Grain and twin boundaries
75.30.Gw Magnetic anisotropy
75.60.Nt Magnetic annealing and temperature-hysteresis effects

X-ray excited optical luminescence detection by scanning near-field optical microscope: A new tool for nanoscience

Silvia Larcheri, Francesco Rocca, Frank Jandard, Daniel Pailharey, Roberto Graziola, Alexei Kuzmin, and Juris Purans

Rev. Sci. Instrum. 79, 013702 (2008); http://dx.doi.org/10.1063/1.2827485 (9 pages) | Cited 6 times

Online Publication Date: 4 January 2008

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Investigations of complex nanostructured materials used in modern technologies require special experimental techniques able to provide information on the structure and electronic properties of materials with a spatial resolution down to the nanometer scale. We tried to address these needs through the combination of x-ray absorption spectroscopy (XAS) using synchrotron radiation microbeams with scanning near-field optical microscopy (SNOM) detection of the x-ray excited optical luminescence (XEOL) signal. This new instrumentation offers the possibility to carry out a selective structural analysis of the sample surface with the subwavelength spatial resolution determined by the SNOM probe aperture. In addition, the apex of the optical fiber plays the role of a topographic probe, and chemical and topographic mappings can be simultaneously recorded. Our working XAS-SNOM prototype is based on a quartz tuning-fork head mounted on a high stability nanopositioning system; a coated optical fiber tip, operating as a probe in shear-force mode; a detection system coupled with the microscope head control system; and a dedicated software/hardware setup for synchronization of the XEOL signal detection with the synchrotron beamline acquisition system. We illustrate the possibility to obtain an element-specific contrast and to perform nano-XAS experiments by detecting the Zn K and W L3 absorption edges in luminescent ZnO and mixed ZnWO4–ZnO nanostructured thin films.
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78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
68.47.Fg Semiconductor surfaces
73.22.-f Electronic structure of nanoscale materials and related systems
71.20.Nr Semiconductor compounds

Vacancy island creation and coalescence using automated scanning tunneling microscopy

R. E. Lake, A. Dean, N. Maheswaranathan, A. P. Lange, M. P. Ray, and C. E. Sosolik

Rev. Sci. Instrum. 79, 013703 (2008); http://dx.doi.org/10.1063/1.2818777 (4 pages)

Online Publication Date: 4 January 2008

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We demonstrate that scanning tunneling microscope tip-surface crash events can be utilized as an efficient means for the creation of predefined island configurations for diffusion studies. Using this method, islands of varying size can be created and placed in close proximity, increasing the probability of initiating and observing coalescence events. Data obtained from crash initiated events on a Ag(111) surface are presented. Relaxation time exponents extracted from these data confirm that our method gives results consistent with previous, sputter-obtained island coalescence studies. We also describe an instrument-control routine developed for these measurements that utilizes commercial imaging and off-the-shelf automation software to automate the tracking of islands or other features by the microscope.
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68.35.Fx Diffusion; interface formation
68.47.De Metallic surfaces
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Novel instrument for surface plasmon polariton tracking in space and time

M. Sandtke, R. J. P. Engelen, H. Schoenmaker, I. Attema, H. Dekker, I. Cerjak, J. P. Korterik, F. B. Segerink, and L. Kuipers

Rev. Sci. Instrum. 79, 013704 (2008); http://dx.doi.org/10.1063/1.2825463 (10 pages) | Cited 11 times

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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07.79.Fc Near-field scanning optical microscopes
68.37.Uv Near-field scanning microscopy and spectroscopy
07.60.Ly Interferometers
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
73.22.Lp Collective excitations
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)

Automating fruit fly Drosophila embryo injection for high throughput transgenic studies

E. Cornell, W. W. Fisher, R. Nordmeyer, D. Yegian, M. Dong, M. D. Biggin, S. E. Celniker, and J. Jin

Rev. Sci. Instrum. 79, 013705 (2008); http://dx.doi.org/10.1063/1.2827516 (7 pages) | Cited 1 time

Online Publication Date: 15 January 2008

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To decipher and manipulate the 14 000 identified Drosophila genes, there is a need to inject a large number of embryos with transgenes. We have developed an automated instrument for high throughput injection of Drosophila embryos. It was built on an inverted microscope, equipped with a motorized xy stage, autofocus, a charge coupled device camera, and an injection needle mounted on a high speed vertical stage. A novel, micromachined embryo alignment device was developed to facilitate the arrangement of a large number of eggs. The control system included intelligent and dynamic imaging and analysis software and an embryo injection algorithm imitating a human operator. Once the injection needle and embryo slide are loaded, the software automatically images and characterizes each embryo and subsequently injects DNA into all suitable embryos. The ability to program needle flushing and monitor needle status after each injection ensures reliable delivery of biomaterials. Using this instrument, we performed a set of transformation injection experiments. The robot achieved injection speeds and transformation efficiencies comparable to those of a skilled human injector. Because it can be programed to allow injection at various locations in the embryo, such as the anterior pole or along the dorsal or ventral axes, this system is also suitable for injection of general biochemicals, including drugs and RNAi.
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87.85.M- Biotechnology
87.80.Ek Mechanical and micromechanical techniques
87.14.gk DNA
87.85.St Robotics
87.80.St Genomic techniques

Highly efficient tip-enhanced Raman spectroscopy and microscopy of strained silicon

Alvarado Tarun, Norihiko Hayazawa, Masashi Motohashi, and Satoshi Kawata

Rev. Sci. Instrum. 79, 013706 (2008); http://dx.doi.org/10.1063/1.2832347 (10 pages) | Cited 14 times

Online Publication Date: 16 January 2008

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We present a versatile tip-enhanced Raman spectroscopy (TERS) system that permits efficient illumination and detection of optical properties in the visible range to obtain high signal-to-noise Raman signals from surfaces and interfaces of materials using an edge filter. The cutoff wavelength of the edge filter is tuned by changing the angle of incident beam to deliver high incident power and effectively collect scattered near-field signals for nanoscopic investigation in depolarized TERS configuration. The dynamic design of the instrument provides a unique combination of features that allows us to perform reflection or transmission mode TERS to cover both opaque and transparent samples. A detailed description of improvements of TERS was carried out on a thin strained silicon surface layer. The utilization of an edge filter for shorter collection time, specialized tip for higher field enhancement and for elimination of Raman signal from the tip, shorter wavelength, sample orientation relative to probing polarization, and depolarized configuration for higher contrast Raman signal is discussed.
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78.30.-j Infrared and Raman spectra
78.66.Db Elemental semiconductors and insulators
78.40.Fy Semiconductors
78.68.+m Optical properties of surfaces

Control of voice coil motor nanoscanners for an atomic force microscopy system using a loop shaping technique

Woosub Youm, Jongkyu Jung, SungQ Lee, and Kyihwan Park

Rev. Sci. Instrum. 79, 013707 (2008); http://dx.doi.org/10.1063/1.2829990 (6 pages) | Cited 1 time

Online Publication Date: 17 January 2008

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The voice coil motor nanoscanner has the advantages of large working range, easy control, and low cost compared to the conventional lead zirconate titanate driven nanoscanner. However, it has a small damping problem which causes mechanical vibration. The mechanical vibration reduces the accuracy as well as servobandwidth, which deteoriates the atomic force microscopy (AFM) image of the samples. In order to solve the vibration problem, the loop shaping technique [for vertical (z)] and input prefilter [for lateral (xy)] are applied. Experimental results of the proposed techniques are presented for vertical (z) and lateral (xy) scanner. Finally, the AFM images are provided to investigate its effect.
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42.79.Ls Scanners, image intensifiers, and image converters
84.50.+d Electric motors
62.30.+d Mechanical and elastic waves; vibrations
68.37.Ps Atomic force microscopy (AFM)
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