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May 2003

Volume 74, Issue 5, pp. 2631-2941

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Techniques and mechanisms applied in electron cyclotron resonance sources for highly charged ions

A. G. Drentje

Rev. Sci. Instrum. 74, 2631 (2003); http://dx.doi.org/10.1063/1.1569408 (15 pages) | Cited 33 times

Online Publication Date: 29 April 2003

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Electron cyclotron resonance ion sources are delivering beams of highly charged ions for a wide range of applications in many laboratories. For more than two decades, the development of these ion sources has been to a large extent an intuitive and experimental enterprise. Much effort has been spent in theoretical work, but a consistent description still is not available. From experimental activities, scaling rules have been formulated, which have successfully been used for the construction of more powerful devices. Special techniques like the coating of the plasma chamber walls, usage of secondary electron emission materials, installation of a biased probe or disk, and mixing the supply gas with other gas species, are generally being incorporated for improving the output of highly charged ions. Various ideas to understand these mechanisms have been brought up, again without consistent description. In experiments, the effect of the techniques with respect to physical parameters, i.e., reducing the plasma potential and/or lowering the ion temperature, has been demonstrated. In a recent study, the requirement of charge neutrality in the fluxes from the plasma to the walls of the plasma chamber has been evaluated; this shows that the occurrence of Simon currents in the conducting walls plays an important role in determining the value of the self-adjusting plasma potential. Most of the special techniques do affect the Simon currents, and therefore the plasma potential, thus the confinement. The effect of the gas mixing technique is mainly (but not exclusively) to decrease the ion temperature, and by that to increase the confinement. The present state of understanding the various techniques will be reviewed. © 2003 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
52.58.-c Other confinement methods
52.50.Dg Plasma sources
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back to top OPTICS; ATOMS and MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Very high long-term stability synchroscan streak camera

Wilfried Uhring, Chantal Virginie Zint, Patrick Summ, and Bernard Cunin

Rev. Sci. Instrum. 74, 2646 (2003); http://dx.doi.org/10.1063/1.1569409 (8 pages) | Cited 4 times

Online Publication Date: 29 April 2003

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In this article, we present the drifts phenomena that affect the temporal resolution of a standard synchroscan streak camera and some techniques to correct them in order to enhance the long-term resolution of these cameras. First, we give a comprehensive list of the components of the synchroscan streak camera which are sensitive to temporal and thermal drift: from the trigger circuit to the deflection plate of the tube. The way in which these components make the camera drift is explained and then quantified. A measure of drift realized on two streak cameras at the same time and in the same conditions (the same synchroscan signal) shows that each camera has its own intrinsic and stochastic drift. Second, two techniques to stabilize the camera are then described. The first method stabilizes the phase difference between the synchroscan signal and the deflection plate voltage. The second uses a laser reference trace on the phosphor screen and a digital data processing technique to reach the ultimate stability. The results show that a stabilized camera can be used immediately after it is turned on (due to suppression of the warm-up time) and still has very good temporal resolution even with a long-time exposure (2.4 ps full width at half maximum with a time exposure of 2 h has been achieved). This allows more exploration in the detection of very weak signals. © 2003 American Institute of Physics.
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07.68.+m Photography, photographic instruments; xerography

Multichannel detector–collimator for powder diffraction measurements at energy scanning x-ray absorption spectroscopy synchrotron radiation beamlines for high-pressure and high-temperature applications

Adriano Filipponi, Valentina M. Giordano, Simone De Panfilis, Andrea Di Cicco, Emiliano Principi, Angela Trapananti, Michael Borowski, and Jean-Paul Itiè

Rev. Sci. Instrum. 74, 2654 (2003); http://dx.doi.org/10.1063/1.1568553 (10 pages) | Cited 10 times

Online Publication Date: 29 April 2003

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We describe a modular detector system suitable to intercept the diffracted x-ray radiation (Debye–Scherrer rings) in a transmission geometry setup at monochromatic tunable synchrotron radiation beamlines. The detector consists of several independent channels composed of a motorized front slit and a rear detector slit system which can be mounted in either a vertical or a horizontal configuration. The detectors are placed at fixed scattering angles 2θ and the diffraction scan is performed by tuning the monochromator energy. The availability of a multidetector system allows one to cover a wide range of scattering vectors with limited range energy scans. The photon sensitive elements are based on CdZnTe solid state detectors which are used at ambient temperature for high efficiency photon counting in the 10–60 keV range. In alternative, conventional NaI(Tl) scintillation detectors can be integrated in the setup. The system can be mounted in a high-resolution configuration and typical widths in the range ΔE/E ≃ 10−3 have been obtained for Bragg peaks. In these conditions the sensitivity to changes in the lattice spacing is better than 10−4. This detector system fully complements the experimental devices usually available at x-ray absorption spectroscopy beamlines and the short range structural information obtained using the x-ray absorption fine structure technique. Typical applications include high-pressure and high-temperature investigations of condensed matter. © 2003 American Institute of Physics.
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07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
61.05.cp X-ray diffraction
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
07.85.Qe Synchrotron radiation instrumentation
78.70.Dm X-ray absorption spectra
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
07.20.Ka High-temperature instrumentation; pyrometers

New Pockels field sensor with ferroelectric liquid-crystal phase modulator

K. Tada, Y. Tanaka, T. Takada, and Y. Murooka

Rev. Sci. Instrum. 74, 2664 (2003); http://dx.doi.org/10.1063/1.1568537 (6 pages) | Cited 1 time

Online Publication Date: 29 April 2003

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A new optical field sensor for measuring the electric field close to an electrical discharge has been developed. The new system that uses both P- and S-polarized light-division and azimuth angle modulation methods has been devised and investigated. By using a ferroelectric liquid-crystal phase modulator instead of an azimuth angle modulator, it has been possible to eliminate noise from the optical field measurement system, specifically, the birefringence effects in a long optical fiber cable. The optical cable is used for connecting a Pockels field sensor located close to the discharge with the main system located at the ground. Furthermore, it has been possible to compensate for the sensitivity difference between two optical detectors for converting P- and S-polarized light waves to an electrical signal. From this, it is found that by using a light reflection technique, the measurable minimum field strength is reduced from 100 kV/m to 1.0 kV/m in the discharge region. If the smallest phase change in the system is set to be less than 10−3 [rad], the measurable minimum field strength is reduced to 0.1 kV/m. The possible use of the probe is also considered for checking for damage caused by cosmic rays to the insulating skin of a spacecraft. © 2003 American Institute of Physics.
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42.81.Pa Sensors, gyros
42.79.Hp Optical processors, correlators, and modulators
78.20.Jq Electro-optical effects
77.80.-e Ferroelectricity and antiferroelectricity
42.70.Df Liquid crystals
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals
07.60.Vg Fiber-optic instruments

Thinning-out in optimized pulse shaping method using genetic algorithm

R. Mizoguchi, K. Onda, S. S. Kano, and A. Wada

Rev. Sci. Instrum. 74, 2670 (2003); http://dx.doi.org/10.1063/1.1569398 (5 pages) | Cited 9 times

Online Publication Date: 29 April 2003

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An optical pulse shaping system using a spatial light modulator (SLM) controlled by genetic algorithm (GA) optimization was improved and we demonstrated that the time for finding the optimal condition could be shortened by a proposed “thinning out” method. In this method, GA controls only every N (N = 1, 2, 4, 8, 16) pixel in the SLM. The conditions of the remaining pixels are derived by interpolation. The effectiveness of this method was verified by the pulse compression of chirped femtosecond pulses and the increase in the two-photon excitation efficiency of α-perylene crystals. The influence of the thinning out on the pulse shape is discussed, and an advanced method is proposed. It is shown that the disadvantages of the thinning out method can be compensated for by changing the value of N during optimization. © 2003 American Institute of Physics.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Hp Optical processors, correlators, and modulators

Design of a fast in situ infrared diagnostic tool

M. F. A. M. van Hest, A. Klaver, D. C. Schram, and M. C. M. van de Sanden

Rev. Sci. Instrum. 74, 2675 (2003); http://dx.doi.org/10.1063/1.1564273 (10 pages)

Online Publication Date: 29 April 2003

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Conventional Fourier transform infrared (FTIR) spectroscopes cannot be used to perform real time in situ infrared reflection absorption spectroscopy at monolayer sensitivity for high deposition rates (a couple of tens to hundreds of nm/s) which can be obtained when using an expanding thermal deposition plasma. Therefore a new analysis tool has been developed. The tool is based on a fast optical scanner in combination with conventional grating technology. This results in a loss of spectral range with respect to FTIR spectroscopes, but a significant gain is obtained in time resolution. For the combination used this makes it possible to measure at time resolution as low as 1.3 ms and resolution of 24 cm−1 at 1000 cm−1. The absorption sensitivity for single reflection at the best time resolution is approximately 10−2, but can be improved by using signal enhancement techniques. Here attenuated total reflection is used and the best sensitivity obtained is approximately 10−3, which is close to monolayer sensitivity for various absorption bands in the infrared spectrum of silicon oxide films. Monolayer sensitivity can be obtained by averaging multiple spectra, however this will cause the time resolution to decrease. © 2003 American Institute of Physics.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
42.79.Ls Scanners, image intensifiers, and image converters
42.79.Dj Gratings

Detection of cold metastable atoms at a surface

D. Schneble, M. Hasuo, T. Anker, T. Pfau, and J. Mlynek

Rev. Sci. Instrum. 74, 2685 (2003); http://dx.doi.org/10.1063/1.1561597 (5 pages) | Cited 3 times

Online Publication Date: 29 April 2003

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A scheme for the detection of cold metastable atoms at surfaces with spatial and temporal resolution is studied experimentally, using methods of laser cooling and atom optics. Electron emission yields for deexcitation of the metastable states 1s5(J = 2) and 1s3(J = 0) of argon at a gold surface are compared with a technique that is based on optical pumping and the use of an evanescent-wave atom mirror as an internal-state filter, and are found to agree to within an uncertainty of 10%. The application of the detection scheme to time-of-flight spectroscopy of cold atom clouds is demonstrated. The detector has a field of view of 3 mm diameter, a spatial resolution of order 100 μm, and a time resolution of 20 μs, and the single-atom detection efficiency near the center of the field of view is 14% in the linear counting regime of up to 106 atoms/s. © 2003 American Institute of Physics.
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34.35.+a Interactions of atoms and molecules with surfaces
34.50.-s Scattering of atoms and molecules
37.10.De Atom cooling methods
37.10.Gh Atom traps and guides
back to top NUCLEAR PHYSICS, FUSION and PLASMAS

First results of pinhole neutron imaging for inertial confinement fusion

C. R. Christensen, Cris W. Barnes, G. L. Morgan, M. Wilke, and D. C. Wilson

Rev. Sci. Instrum. 74, 2690 (2003); http://dx.doi.org/10.1063/1.1569407 (5 pages) | Cited 9 times

Online Publication Date: 29 April 2003

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Results are presented for the first implementation of pinhole imaging of inertial confinement fusion-produced neutrons. Raw images are shown, together with mathematical reconstructions of the source objects, for both spherical and asymmetric implosions. These reconstructions are considerably sharpened with respect to the raw images. They rely on the accurate calculation of the point-spread function, including neutron penetration into the material defining the pinhole. Proton recoil in the scintillator material and irregularity in scintillator fiber packing must be considered. The statistics of the system are inferred, which allows the use of simulations to demonstrate the robustness of the reconstructions to noise. © 2003 American Institute of Physics.
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28.52.Lf Components and instrumentation
42.30.Wb Image reconstruction; tomography
42.30.Lr Modulation and optical transfer functions

CO2 laser polarimeter for electron density profile measurement on the Large Helical Device

T. Akiyama, S. Tsuji-Iio, R. Shimada, K. Nakayama, S. Okajima, M. Takahashi, K. Terai, K. Tanaka, T. Tokuzawa, and K. Kawahata

Rev. Sci. Instrum. 74, 2695 (2003); http://dx.doi.org/10.1063/1.1564276 (9 pages) | Cited 13 times

Online Publication Date: 29 April 2003

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We developed a three-channel tangential CO2 laser polarimeter to measure electron densities on the Large Helical Device. Our system aims to obtain not only the line averaged electron density but also the electron density profile. The achieved resolution of the Faraday rotation angle was 0.01° with a response time of 3 ms by digital complex demodulation combined with digital filtering. The phase fluctuations whose amplitude is typically 0.05° with a time constant of several seconds were observed. It was found that they were caused by beam axis fluctuations from bench top experiments. In the case of pellet injected plasmas it was demonstrated that the polarimeter could measure the time evolution of the Faraday rotation with high reliability and resolution. The calibrated rotation angle of all chords were well consistent with interferometer data. Assuming the functional dependence of the density profile, we estimated the density profile after pellet injections from three-channel polarimeter data iteratively. As a result, obtained profiles agreed with those measured with the 13-channel far infrared interferometer. © 2003 American Institute of Physics.
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52.55.Jd Magnetic mirrors, gas dynamic traps
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Kn Thermodynamics of plasmas

Improved planar radio frequency inductively coupled plasma configuration in plasma immersion ion implantation

D. L. Tang, R. K. Y. Fu, X. B. Tian, and P. K. Chu

Rev. Sci. Instrum. 74, 2704 (2003); http://dx.doi.org/10.1063/1.1568559 (5 pages) | Cited 6 times

Online Publication Date: 29 April 2003

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Plasmas with higher density and better uniformity are produced using an improved planar radio frequency (rf) inductively coupled plasma configuration in plasma immersion ion implantation (PIII). An axial magnetic field is produced by external electromagnetic coils outside the discharge chamber. The rf power can be effectively absorbed by the plasma in the vicinity of the electron gyrofrequency due to the enhanced resonant absorption of electromagnetic waves in the whistler wave range, which can propagate nearly along the magnetic field lines thus greatly increases the plasma density. The plasma is confined by a longitudinal multipolar cusp magnetic field made of permanent magnets outside the process chamber. It can improve the plasma uniformity without significantly affecting the ion density. The plasma density can be increased from 3×109 to 1×1010 cm−3 employing an axial magnetic field of several Gauss at 1000 W rf power and 5×10−4 Torr gas pressure. The nonuniformity of the plasma density is less than 10% and can be achieved in a process chamber with a diameter of 600 mm. Since the plasma generation and process chambers are separate, plasma extinction due to the plasma sheath touching the chamber wall in high-energy PIII can be avoided. Hence, low-pressure, high-energy, and high-uniformity ion implantation can be accomplished using this setup. © 2003 American Institute of Physics.
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.77.Dq Plasma-based ion implantation and deposition
52.40.Db Electromagnetic (nonlaser) radiation interactions with plasma
52.25.-b Plasma properties

TOBI: A two-laser beam infrared system for time-resolved plasma diagnostics of infrared active compounds

J. B. McManus, D. Nelson, M. Zahniser, L. Mechold, M. Osiac, J. Röpcke, and A. Rousseau

Rev. Sci. Instrum. 74, 2709 (2003); http://dx.doi.org/10.1063/1.1568554 (5 pages) | Cited 22 times

Online Publication Date: 29 April 2003

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A compact and transportable two laser beam infrared (TOBI) system based on infrared absorption spectroscopy has been developed for time-resolved plasma diagnostics. The TOBI system contains two independent tunable diode lasers which can be directed through a plasma or into a multipass cell for exhaust gas detection. Rapid scan software with real-time line shape fitting provides a time resolution up to 10 μs to study chemical kinetic processes of infrared active compounds in plasmas. The capabilities of the TOBI system have been demonstrated in plasmas of pulsed H2–N2 surface wave and in pulsed air–CH4 dc discharges. © 2003 American Institute of Physics.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
32.30.Bv Radio-frequency, microwave, and infrared spectra
33.20.Ea Infrared spectra
back to top MICROSCOPY and IMAGING

Development of a multiphoton fluorescence lifetime imaging microscopy system using a streak camera

R. V. Krishnan, H. Saitoh, H. Terada, V. E. Centonze, and B. Herman

Rev. Sci. Instrum. 74, 2714 (2003); http://dx.doi.org/10.1063/1.1569410 (8 pages) | Cited 22 times

Online Publication Date: 29 April 2003

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We report the development and detailed calibration of a multiphoton fluorescence lifetime imaging system (FLIM) using a streak camera. The present system is versatile with high spatial (∼0.2 μm) and temporal (∼50 ps) resolution and allows rapid data acquisition and reliable and reproducible lifetime determinations. The system was calibrated with standard fluorescent dyes and the lifetime values obtained were in very good agreement with values reported in the literature for these dyes. We also demonstrate the applicability of the system to FLIM studies in cellular specimens including stained pollen grains and fibroblast cells expressing green florescent protein. The lifetime values obtained matched well with those reported earlier by other groups for these same specimens. Potential applications of the present system include the measurement of intracellular physiology and fluorescence resonance energy transfer imaging, which are discussed in the context of live cell imaging. © 2003 American Institute of Physics.
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87.64.mn Multiphoton
33.50.Dq Fluorescence and phosphorescence spectra
78.55.Kz Solid organic materials
87.15.M- Spectra of biomolecules

A probe-positioning method with two-dimensional calibration pattern for micro-multi-point probes

Wataru Yashiro, Ichiro Shiraki, and Kazushi Miki

Rev. Sci. Instrum. 74, 2722 (2003); http://dx.doi.org/10.1063/1.1569390 (4 pages) | Cited 3 times

Online Publication Date: 29 April 2003

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A probe-positioning method for micro-multi-point probes that can be independently driven is proposed. By the electron-beam lithography technique, we fabricated a 0.5 mm×0.5 mm-sized probe-positioning pattern matrix consisting of 750 nm×750 nm-sized cells. Each cell has 150 nm×150 nm-sized pits that represent a bit array, which specifies its address. Reading the address information on the pattern with the microprobes allowed us not only to determine the probe positions, but also to calibrate the orientation and dimension of each scan. © 2003 American Institute of Physics.
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07.79.Lh Atomic force microscopes
06.20.F- Units and standards
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
81.16.Nd Micro- and nanolithography

Noncontact atomic force microscopy: Stability criterion and dynamical responses of the shift of frequency and damping signal

G. Couturier, R. Boisgard, L. Nony, and J. P. Aimé

Rev. Sci. Instrum. 74, 2726 (2003); http://dx.doi.org/10.1063/1.1564274 (9 pages) | Cited 14 times

Online Publication Date: 29 April 2003

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The aim of this article is to provide a complete analysis of the behavior of a noncontact atomic force microscope (NC-AFM). We start with a review of the equations of motion of a tip interacting with a surface in which the stability conditions are first revisited for tapping mode. Adding the equations of automatic gain control (AGC), which insures constant amplitude of the oscillations in the NC-AFM, to the equations of motion of the tip, a new analytical stability criterion that involves proportional and integral gains of AGC is deduced. Stationary solutions for the shift of frequency and for the damping signal are obtained. Special attention is paid to the damping signal in order to clarify its physical origin. The theoretical results are then compared to those given by a virtual machine. The virtual machine is a set of equations solved numerically without any approximation. The virtual machine is of great help in understanding the dynamical behavior of the NC-AFM as images are recorded. Transient responses of the shift in frequency and of the damping signal are discussed in relation to the values of proportional and integral gains of AGC. © 2003 American Institute of Physics.
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07.79.Lh Atomic force microscopes
46.40.Ff Resonance, damping, and dynamic stability

A scanning capacitance microscope based on a coaxial resonator: High sensitivity and cheap and compact design without the use of lock-in detection systems

Marco Ferrara and Ottorino Odoardi

Rev. Sci. Instrum. 74, 2735 (2003); http://dx.doi.org/10.1063/1.1569389 (9 pages)

Online Publication Date: 29 April 2003

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We describe a scanning capacitance microscope based on an oscillator whose frequency is controlled by a coaxial line λ/2 resonator tuned at the terminal ends by two capacitances, one obtained by a varicap, the other due to the tip-sample junction. Both the values of the tuning capacitances can be changed by a biasing voltage applied, respectively, to the varicap or to a piezoceramic which controls the tip-sample distance. The two input voltage controlled oscillator is part of a phase locked loop and, depending on the input used, it is possible to perform constant height or constant capacitance analysis. In the first case, the instrument gives the profile of the tip sample capacitance while, in the second case, constant capacitance profiles are obtained. Theoretical analysis and experimental results are reported. Capacitance–voltage metal–oxide–semiconductor curves and the images of a calibration grating obtained with our instrument are also reported. © 2003 American Institute of Physics.
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07.79.-v Scanning probe microscopes and components
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)

Combined Kerr microscope and magnetic force microscope for variable temperature ultrahigh vacuum investigations

D. Peterka, A. Enders, G. Haas, and K. Kern

Rev. Sci. Instrum. 74, 2744 (2003); http://dx.doi.org/10.1063/1.1568556 (5 pages) | Cited 9 times

Online Publication Date: 29 April 2003

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A new system combining a Kerr microscope and a magnetic force microscope for the study of magnetic domains in ultrathin films under ultrahigh vacuum conditions is presented. Due to the overlapping imaging range of both techniques magnetic domains can be investigated over a lateral range from millimeter down to fractions of a micrometer. Experiments can be done at variable temperatures, from 80 K to 600 K. First results are presented showing the same magnetic domain in a three monolayer Fe film on Cu (100) imaged with both techniques. © 2003 American Institute of Physics.
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75.70.Ak Magnetic properties of monolayers and thin films
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.50.Bb Fe and its alloys
68.37.Rt Magnetic force microscopy (MFM)
07.79.Pk Magnetic force microscopes
78.20.Ls Magneto-optical effects
78.66.Bz Metals and metallic alloys

Superconducting microwave resonator for millikelvin magnetic resonance force microscopy

H. J. Mamin, R. Budakian, and D. Rugar

Rev. Sci. Instrum. 74, 2749 (2003); http://dx.doi.org/10.1063/1.1564278 (5 pages) | Cited 9 times

Online Publication Date: 29 April 2003

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We have fabricated a superconducting resonator capable of generating a strong microwave magnetic field in a small (100 μm) volume for low temperature magnetic resonance experiments. While the resonator was specifically developed for use at millikelvin temperatures in a dilution refrigerator, where the total cooling power is limited to a few hundred microwatts, it is also useful at temperatures up to 5 K. The resonator consists of a 220 μm diameter, 2-1/2 turn niobium coil resonating with a short section of niobium microstripline. At a resonance frequency of 3 GHz, the loaded Q of the resonator was 780. The field strength was characterized by performing electron spin nutations. Operating at 100 mK with 320 μW of dissipated power, the resonator generated a field of 4 G at a distance of 100 μm from the coil. © 2003 American Institute of Physics.
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07.79.Pk Magnetic force microscopes
85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
84.40.Az Waveguides, transmission lines, striplines
back to top CONDENSED MATTER; MATERIALS

Microspectroscopic two-dimensional Fermi surface mapping using a photoelectron emission microscope

M. Kotsugi, W. Kuch, F. Offi, L. I. Chelaru, and J. Kirschner

Rev. Sci. Instrum. 74, 2754 (2003); http://dx.doi.org/10.1063/1.1569404 (5 pages) | Cited 9 times

Online Publication Date: 29 April 2003

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We demonstrate the use of a photoelectron emission microscope in connection with a retarding field electron energy analyzer for the fast acquisition of two-dimensional momentum resolved photoelectron angular distribution patterns. This opens the possibility to combine spatial, momentum, and energy resolution of photoelectrons within the same instrument. We have applied this to observe the Cu(001) Fermi surface from a selected region of the sample. A well defined bulk Fermi surface is quickly mapped in this way. © 2003 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
79.60.Bm Clean metal, semiconductor, and insulator surfaces
68.37.Vj Field emission and field-ion microscopy
68.35.B- Structure of clean surfaces (and surface reconstruction)

The high-flux backscattering spectrometer at the NIST Center for Neutron Research

A. Meyer, R. M. Dimeo, P. M. Gehring, and D. A. Neumann

Rev. Sci. Instrum. 74, 2759 (2003); http://dx.doi.org/10.1063/1.1568557 (19 pages) | Cited 62 times

Online Publication Date: 29 April 2003

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We describe the design and current performance of the high-flux backscattering spectrometer located at the NIST Center for Neutron Research. The design incorporates several state-of-the-art neutron optical devices to achieve the highest flux on sample possible while maintaining an energy resolution of less than 1 μeV. Foremost among these is a novel phase-space transformation chopper that significantly reduces the mismatch between the beam divergences of the primary and secondary parts of the instrument. This resolves a long-standing problem of backscattering spectrometers, and produces a relative gain in neutron flux of 4.2. A high-speed Doppler-driven monochromator system has been built that is capable of achieving energy transfers of up to ±50 μeV, thereby extending the dynamic range of this type of spectrometer by more than a factor of 2 over that of other reactor-based backscattering instruments. © 2003 American Institute of Physics.
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29.30.Hs Neutron spectroscopy
07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)

Neutron sample cell suitable for the diffraction of aligned biomaterials and capable of exerting up to 370 MPa of hydrostatic pressure

M. J. Watson, M.-P. Nieh, T. A. Harroun, and J. Katsaras

Rev. Sci. Instrum. 74, 2778 (2003); http://dx.doi.org/10.1063/1.1568555 (4 pages) | Cited 5 times

Online Publication Date: 29 April 2003

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We describe a temperature controlled sample cell suitable for the study of biomimetic materials (e.g., lipid bilayers) using neutron diffraction, and capable of exerting hydrostatic pressures of up to 370 MPa. The advantage of this sample cell, compared to previous high-pressure cells of its type, is that it allows for the use of samples aligned on a solid support which, compared to “powder” or so-called liposomal preparations, requires only small amounts of sample and allows for the clear differentiation between in-plane and out-of-plane structure.
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61.05.fm Neutron diffraction
87.64.Bx Electron, neutron and x-ray diffraction and scattering
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells

A simple and efficient cryogenic loading technique for diamond anvil cells

Michael Pravica and Benjaman Remmers

Rev. Sci. Instrum. 74, 2782 (2003); http://dx.doi.org/10.1063/1.1568551 (2 pages) | Cited 4 times

Online Publication Date: 29 April 2003

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We have developed a simple and time-efficient cryogenic loading technique for diamond anvil cells (DACs) using a glovebox. By using liquid nitrogen as a thermal reservoir to condense gaseous samples into the solid state, manually inserting the sample into an empty gasket, and then closing the DAC to seal a sample, we have easily loaded high-purity samples of carbon dioxide in less than 1 h. This technique has significant advantages over currently used methods to load cryogenic solids in both cost and time and can be used for a wide variety of solids with melting temperatures above 77 K. © 2003 American Institute of Physics.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
06.60.Ei Sample preparation (including design of sample holders)

Two-color photoionization spectroscopy using vacuum ultraviolet synchrotron radiation and infrared optical parametric oscillator laser

Ximei Qian, Tao Zhang, C. Y. Ng, A. H. Kung, and Musa Ahmed

Rev. Sci. Instrum. 74, 2784 (2003); http://dx.doi.org/10.1063/1.1569402 (7 pages) | Cited 14 times

Online Publication Date: 29 April 2003

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A two-color, vacuum ultraviolet (VUV)-infrared (IR), photoionization study using monochromatized undulator VUV synchrotron radiation and high-repetition rate IR optical parametric oscillator (OPO) laser source has been demonstrated at the Chemical Dynamics Beamline of the Advanced Light Source. The OPO setup, optical alignment, and ion detection arrangement are described. The VUV-IR ionization spectrum of Ar has been recorded in the energy region between the ionization thresholds for Ar+(2P3/2) and Ar+(2P1/2) to illustrate the feasibility and efficacy of this scheme as a general approach for high-resolution two-color photoionization studies. The autoionization resonances of the Ar(np′ and nf′) Rydberg series are resolved up to the principal quantum number of n=57, showing that the optical resolution of 0.3 cm−1 (full width at half maximum) achieved in this two-color photoionization study is mostly limited by the bandwidth of the IR OPO laser and the Doppler width due to the random motion of the Ar sample. © 2003 American Institute of Physics.
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32.80.Fb Photoionization of atoms and ions
32.80.Zb Autoionization
32.30.Jc Visible and ultraviolet spectra
32.30.Bv Radio-frequency, microwave, and infrared spectra

Ultrahigh-vacuum soft x-ray reflectometer

Maurizio Sacchi, Carlo Spezzani, Piero Torelli, Antoine Avila, Renaud Delaunay, and Coryn F. Hague

Rev. Sci. Instrum. 74, 2791 (2003); http://dx.doi.org/10.1063/1.1568552 (5 pages) | Cited 6 times

Online Publication Date: 29 April 2003

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We have designed, built, and tested a new instrument for soft x-ray scattering experiments. The reflectometer works under ultrahigh vacuum and permits in situ preparation and characterization of the samples. In particular, deposition and sputtering operations can be performed while measuring x-ray scattering. We report the results of test measurements performed using synchrotron radiation. The precision of the combined positioning of sample and detector angles is better than 0.01°. Separately, sample and detector rotations have a repeatability that is better than 0.005°. Applications will be in the field of surface physics, with emphasis on magnetic properties of surfaces, thin films, and multilayered structures. © 2003 American Institute of Physics.
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07.60.Hv Refractometers and reflectometers
78.70.Ck X-ray scattering
61.05.cm X-ray reflectometry (surfaces, interfaces, films)
68.49.Uv X-ray standing waves

Differential pressure experiment to probe hole growth in freely standing polymer films

C. B. Roth, B. G. Nickel, J. R. Dutcher, and K. Dalnoki-Veress

Rev. Sci. Instrum. 74, 2796 (2003); http://dx.doi.org/10.1063/1.1568541 (9 pages) | Cited 8 times

Online Publication Date: 29 April 2003

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We have developed a sensitive experiment which allows the measurement of the growth of holes in thin freely standing polystyrene (PS) films at elevated temperatures. In the experiment, a constant small pressure difference is applied and maintained across the freely standing film, and the formation and growth of holes is detected as a flow of air through the film. From measurements of freely standing PS films for which the glass transition temperature Tg is equal to the bulk value Tgbulk, as well as for films that are sufficiently thin that Tg is 30 °C less than Tgbulk, we find that substantial chain mobility occurs only at temperatures that are comparable to Tgbulk. The results can be interpreted as a shear thinning effect, which is consistent with previous optical microscopy measurements of hole growth in freely standing PS films. © 2003 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
61.41.+e Polymers, elastomers, and plastics
68.55.-a Thin film structure and morphology
81.40.Vw Pressure treatment
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
62.50.-p High-pressure effects in solids and liquids
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep

Electrical conductivity measurements of oxides from molten state to glassy state

Claire Simonnet, Jean Phalippou, Mohammed Malki, and Agnès Grandjean

Rev. Sci. Instrum. 74, 2805 (2003); http://dx.doi.org/10.1063/1.1564272 (6 pages) | Cited 5 times

Online Publication Date: 29 April 2003

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This article describes an experimental setup designed to measure the electrical conductivity of molten and viscous oxides from 1200 to 400 °C. The “4-electrode” method was adapted to perform impedance measurements over wide temperature and frequency ranges. High-frequency electrode effects were calculated and eliminated. Low-frequency electrode polarization was avoided with the 4-electrode configuration. The ac impedance was measured at one immersion depth. Calibration and complex impedance analysis were necessary to obtain the electrical conductivity of the melt. The results of this technique for a borosilicate melt are presented and compared with those of high-temperature calibration-free solid-state measurements, and their accuracy is evaluated. © 2003 American Institute of Physics.
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84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
06.20.F- Units and standards
81.05.Kf Glasses (including metallic glasses)
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