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Nov 1992

Volume 63, Issue 11, pp. 5217-5488

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Ion sources for ion beam assisted thin‐film depositiona)

W. Ensinger

Rev. Sci. Instrum. 63, 5217 (1992); http://dx.doi.org/10.1063/1.1143432 (17 pages) | Cited 24 times

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Ion beam assisted deposition (IBAD) is a coating technique which combines a thin‐film deposition method such as evaporation with irradiation by highly energetic ions from an ion source. Application of an ion source and a vapor source which are operated independently of each other render the IBAD technique highly controllable, reproducible, and flexible. Ion flux, atom flux, ion energy, ion impact angle, and other parameters can be controlled independently over a wide range. In order to take advantage of the beneficial features of this technique and obtain optimum process conditions ion sources with special properties are required. In this article different ion source types and equipment which has been used for IBAD to‐date are presented and their special features discussed. Ion sources which should be applicable for IBAD are described. Finally, general requirements of IBAD ion sources are discussed.
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81.15.Jj Ion and electron beam-assisted deposition; ion plating
07.77.-n Atomic, molecular, and charged-particle sources and detectors

Beam divergence and ion density measurements for an induction coupled ion beam source

J. R. Pai and N. Venkatramani

Rev. Sci. Instrum. 63, 5234 (1992); http://dx.doi.org/10.1063/1.1143433 (3 pages)

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In this article the ion beam of H+ and Ar+ produced from the low‐pressure radio frequency ionized plasma is analyzed for beam divergence. The divergence measurement method adopted for a low‐energy beam is described. The divergence values for H+ and Ar+, respectively, are 0.4° and 1.1° for a beam energy of 2.5 kV. It is found that the beam divergence varies with the extraction voltage. In case of H+ beam, the divergence value varies from 2.8° to 0.4° for the extraction voltage of 500 V to 2.5 kV, and in the case of Ar+ beam this value is from 1.3° to 1.1° for the extraction voltage of 1000 V to 2.5 kV. The extraction electrode is concave outward as shown in the figure of the extraction system. The rf plasma is diagnosed using the double‐probe technique for ion density estimation. The axial variation of the electron density and the electron temperature are obtained for both hydrogen as well as argon plasmas. The electron density is maximum, near the end of the coil.
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
41.75.Ak Positive-ion beams
41.85.Ar Particle beam extraction, beam injection
52.50.Dg Plasma sources

An ECH beam monitor for the Texas Experimental Tokamak

D. R. Roberts

Rev. Sci. Instrum. 63, 5237 (1992); http://dx.doi.org/10.1063/1.1143434 (8 pages) | Cited 2 times

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A compact poloidal array of ten receiving antennae has been installed on the high‐field wall (x=+30 cm) of the Texas Experimental Tokamak (TEXT) opposite the electron cyclotron heating (ECH) microwave launch port (x=−45 cm, 60 GHz, 200 kW). Both these antennae and the launching structure are oriented to couple to the ordinary mode in plasma. The array serves as a diagnostic of the unabsorbed, first‐pass ECH microwave power, which includes both power refracted by the equilibrium plasma density gradients and power scattered by density fluctuations. Each antenna has a Δθy=13° poloidal and Δθz=32° toroidal half‐power beam width, corresponding to 12‐dB gain. For refraction studies, interchannel and intrachannel poloidal resolutions are Δy=3.5 and 2.5 cm, respectively, at the array aperture surface. For scattering studies, the wave number selectivity extends from k⊥=0±2.5 cm−1 to k⊥=7±2.5 cm−1.
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52.70.Gw Radio-frequency and microwave measurements
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Influence of cylindrical Langmuir probe diameter on ion branch of its I‐V characteristic

E. V. Shun’ko

Rev. Sci. Instrum. 63, 5245 (1992); http://dx.doi.org/10.1063/1.1143435 (7 pages) | Cited 1 time

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The expression connecting the plasma parameters with the current‐voltage (I‐V) characteristic of the attracting probe is obtained, and it is compared with the electron branches of the experimental probe I‐V characteristics in the range of the probe potentials V≳0. The theoretical and experimental results are in a good agreement. Studies of the influence of a cylindrical Langmuir probe diameter on the ion branch of its I‐V characteristic are described. The transition of the ion charges from the plasma to the measuring circuit of the probe leads to a decrease of the ion concentration in the near‐probe region limited by the Debye length, as is shown. The relations given in the paper enable one to reconstruct the ion concentration by the experimental I‐V characteristic disturbed by the probe.
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52.70.Ds Electric and magnetic measurements
52.40.Hf Plasma-material interactions; boundary layer effects

A multiple‐beam, collective scattering technique for spatially resolved measurement of plasma turbulencea)

B. A. Spivey, L. H. Sverdrup, S. H. Lin, R. G. Trissel, and W. A. Peebles

Rev. Sci. Instrum. 63, 5252 (1992); http://dx.doi.org/10.1063/1.1143436 (7 pages) | Cited 1 time

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Collective Thomson scattering has long been utilized to study electrostatic turbulence in magnetic confinement fusion plasmas with a view to demonstrating a causal link to the observed anomolous transport of heat and particles. However, this goal has been severly hampered by the relatively poor spatial resolution available at the dominant turbulence wave numbers using standard experimental techniques. Good spatial resolution is necessary if adequate comparison of theory and experiment is to occur. The present paper describes the basic principles of a new technique utilizing simultaneous, multiple input beams, a detector array, and coherent tomographic inversion algorithm, which can substantially improve the available spatial resolution for these important measurements. The proposed multiple beam scattering diagnostic offers a spatial resolution of ∼10 cm at a fluctuation wave number of 5 cm−1 when the angular envelope of the beams is 0.1 rad. Optical designs suitable for implementing the multiple beam diagnostic on a large tokamak have been developed.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.35.Ra Plasma turbulence

Two‐dimensional electron density, temperature, and radial drift profiles of a laser plasma by 266 nm collective Thomson scatteringa)

S. M. Cameron, M. D. Tracy, K. G. Estabrook, and J. S. DeGroot

Rev. Sci. Instrum. 63, 5259 (1992); http://dx.doi.org/10.1063/1.1143437 (7 pages) | Cited 6 times

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Collective Thomson scattering measurements performed at 266 nm on an underdense, long scalelength laser‐produced aluminum plasma (nc∼1021 cm−3, Z∼7, Te≥50 eV, L≥100 μm) under moderate irradiance conditions (1011 W/cm2) are used to obtain temporally integrated, spatially resolved (30 μm) electron temperature, density, and radial fluid velocity contours. For an ultraviolet diagnostic wavelength, the effects of inverse bremsstrahlung heating perturbations and refractive turning are significantly reduced, allowing high density coronal conditions in the vicinity of one‐tenth critical to be investigated. Detailed knowledge of these plasma conditions are fundamental prerequisites for understanding the distributed absorption process within fusion plasmas and for validation of the modeling accuracy of hydrodynamic codes. Fluid equations with classical coefficients should accurately apply to the plasma in these experiments because electron thermal transport is in the Spitzer regime, and the authors report relatively good agreement between the experimental results and two‐dimensional LASNEX simulations.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

A dusty plasma device for producing extended, steady state, magnetized, dusty plasma columns

Wenjun Xu, Bin Song, Robert L. Merlino, and Nicola D’Angelo

Rev. Sci. Instrum. 63, 5266 (1992); http://dx.doi.org/10.1063/1.1143438 (4 pages) | Cited 28 times

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We describe a rotating‐drum dust‐dispersal device, which we have used, in conjunction with an existing Q machine, to produce extended, steady state, magnetized plasma columns. The dusty plasma device (DPD) is to be used for the investigation of waves in dusty plasmas and of other plasma/dust aspects. The device is capable of generating dusty plasmas in which as much as ∼90% of the negative charge is attached to dust grains of 1–10 μm size.
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95.55.-n Astronomical and space-research instrumentation
52.75.-d Plasma devices
52.25.Vy Impurities in plasmas

Absolute calibration of the JT‐60U neutron monitors using a 252Cf neutron sourcea)

T. Nishitani, H. Takeuchi, T. Kondoh, T. Itoh, M. Kuriyama, Y. Ikeda, T. Iguchi, and Cris W. Barnes

Rev. Sci. Instrum. 63, 5270 (1992); http://dx.doi.org/10.1063/1.1143439 (9 pages) | Cited 36 times

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Absolutely calibrated measurements of the neutron yield are important for the evaluation of plasma performance such as the fusion gain Q in D–D operating tokamaks. The time‐resolved neutron yield is measured with 235U and 238U fission chambers and 3He proportional counters in the JT‐60U tokamak. The in situ calibration was performed by moving the 252Cf neutron source toroidally through the JT‐60 vacuum vessel. Detection efficiencies of three 235U and two 3He detectors were measured for 92 locations of the neutron point source in toroidal scans at two different major radii. The total detection efficiency for the torus neutron source was obtained by averaging the point efficiencies over the whole toroidal angle. The uncertainty of the resulting detection efficiency for the plasma neutrons is estimated to be ±11%.
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
29.25.Dz Neutron sources
52.55.Fa Tokamaks, spherical tokamaks

High‐flux source of low‐energy neutral beams using reflection of ions from metals

John W. Cuthbertson, Robert W. Motley, and William D. Langer

Rev. Sci. Instrum. 63, 5279 (1992); http://dx.doi.org/10.1063/1.1143440 (10 pages) | Cited 12 times

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Reflection of low‐energy (<100 eV) ions from surfaces can be applied as a method of producing high‐flux beams of low‐energy neutral particles, and is an important effect in several areas of plasma technology, such as in the edge region of fusion devices. We have developed a beam source based on acceleration and reflection of ions from a magnetically confined coaxial rf plasma source. The beam provides a large enough flux (over 4 A ion current, or 5×1016 atoms/cm2 s at 10‐cm range) to allow the energy distribution of the reflected neutrals to be measured despite the inefficiency of detection, by means of an electrostatic cylindrical mirror analyzer coupled with a quadrupole mass spectrometer. Energy distributions have been measured for oxygen, nitrogen, and inert gas ions incident with from 15 to 70 eV reflected from amorphous metal surfaces of several compositions. For ions of lighter atomic mass than the reflecting metal, reflected beams have peaked energy distributions; beams with the peak at 4–32 eV have been measured. The energy and mass dependences of the energy distributions as well as measurements of absolute flux, and angular distribution and divergence are reported. Applications of the neutral beams produced are described.
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29.25.-t Particle sources and targets
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Source of low‐energy hydrogen ions for measuring electron transfer in surface scattering experiments

J. D. Isenberg, H. J. Kwon, and M. Seidl

Rev. Sci. Instrum. 63, 5289 (1992); http://dx.doi.org/10.1063/1.1143441 (5 pages) | Cited 1 time

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We present the design and performance of a beamline which is the source of 5–50‐eV protons for surface scattering experiments. The beamline also incorporates a collector for measuring total secondary ion and electron yields. The beam forming optics are built around a commercially available gas discharge ion gun and produce a mass‐selected, energy‐filtered beam. Results of computer ray tracing are included to illustrate the operation of the beam optics. Tests have produced 50‐pA proton beams 3.5‐mm wide at 5 eV with an energy spread of about 1 eV.
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
41.75.Cn Negative-ion beams

Continuously variable distortion‐free attenuation of high‐power transversely excited atmospheric CO2 laser pulses

P. Sakthivel and P. Mukherjee

Rev. Sci. Instrum. 63, 5294 (1992); http://dx.doi.org/10.1063/1.1143442 (5 pages)

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A new technique for the continuously variable linear attenuation of high‐power transversely excited atmospheric (TEA) CO2 laser pulses is reported. The use of a binary gas mixture comprising SF6 as the absorber and helium or argon as the buffer gas causes a significant enhancement in the saturation intensity, thereby allowing saturation‐free attenuation of TEA CO2 laser pulses up to 1 MW/cm2. A linearly variable dynamic attenuation range of 0–30 dB, and continuously variable attenuation up to 60 dB in a 10‐cm cell length, without spatial or temporal distortion in the attenuated beam is demonstrated.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.68.Ay Propagation, transmission, attenuation, and radiative transfer

Laser microprobe and resonance ionization mass spectrometry for the analysis of trace elements in solids

Tuan‐Yu Hung and Ching‐Shen Su

Rev. Sci. Instrum. 63, 5299 (1992); http://dx.doi.org/10.1063/1.1143443 (7 pages) | Cited 3 times

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A laser microprobe and resonance ionization mass spectrometer (LAM/RIMS) has been designed and constructed by combining a newly designed simple laser microprobe (LAM) with a continuous‐wave (cw) resonance ionization mass spectrometer, for the direct analysis of trace elements in solids. The LAM/RIMS has achieved a simultaneous record of the complete mass spectrum of a solid sample, and a three orders of magnitude enhancement in the detection signal of the selected trace elements in the solid, with precise spatial information, and without the need of sample preparation. A n‐type silicon wafer containing an impurity of sodium in parts per billion order has been easily detected by applying a single shot of an ablation laser pulse and a cw resonance ionization laser. The result has also shown that the sensitivity of the LAM/RIMS for the analysis of selected trace elements is better than the Auger electron spectroscopy and is comparable to neutron activation analysis.
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07.75.+h Mass spectrometers
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Response functions of the laser beam deflection probe for detection of spherical acoustic waves

Janez Diaci

Rev. Sci. Instrum. 63, 5306 (1992); http://dx.doi.org/10.1063/1.1143444 (5 pages) | Cited 19 times

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Detection of spherical acoustic waves by the laser beam deflection probe is examined. The probe is modeled as a linear system transforming acoustic wave form into transient angular deflection of the probe beam. Transfer and step response functions are derived assuming thin Gaussian laser beam and small deflection angle. It is demonstrated that the probe behaves as a half‐order differentiator when short acoustic transients are detected far from the source. Theoretical predictions are compared to the results of frequency analysis of optoacoustic signals detected by the deflection probe. Good agreement is found.
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43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect

Fast calculation of collection efficiency for optical emission spectroscopy of extended sources

M. J. Colgan

Rev. Sci. Instrum. 63, 5311 (1992); http://dx.doi.org/10.1063/1.1143445 (4 pages) | Cited 3 times

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A simple method for estimating the collection efficiency of a nearly ideal optical system is described. Calculation of spatial response functions for the analysis and absolute calibration of optical emission data is emphasized. The simple geometric algorithm presented is several orders of magnitude faster than algorithms based on ray tracing. The method is applied to the case of a radially uniform cylindrical source between parallel plates and the results are in excellent agreement with ray tracing calculations.
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42.79.-e Optical elements, devices, and systems
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers

Two‐dimensional time‐resolved imaging with 100‐ps resolution using a resistive anode photomultiplier tube

S. Charbonneau, L. B. Allard, Jeff F. Young, G. Dyck, and B. J. Kyle

Rev. Sci. Instrum. 63, 5315 (1992); http://dx.doi.org/10.1063/1.1143446 (5 pages) | Cited 22 times

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A two‐dimensional microchannel plate photomultiplier with a position sensitive resistive anode has been integrated with time‐correlated single photon counting circuitry. The result is a very powerful spectroscopic system which combines the very low dark count and parallel collection capabilities of the imaging tube with simultaneous timing information about the individual photon events. The digital x,y and timing information for each photon event is directly stored onto a hard‐disk in real time. When the detector is placed at the output of a spectrometer, the system provides software‐controllable arbitrary time windowing of complete spectra. When used as an image recorder, the system provides software‐controllable time windowing of entire two‐dimensional images, with ∼100‐ps effective frame times.
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07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
29.40.-n Radiation detectors

Interferometric measurements of the diameters of a single‐crystal silicon sphere

K. Fujii, M. Tanaka, Y. Nezu, K. Nakayama, R. Masui, and G. Zosi

Rev. Sci. Instrum. 63, 5320 (1992); http://dx.doi.org/10.1063/1.1143447 (6 pages) | Cited 20 times

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A new interferometer has been developed for the accurate determination of the density of a silicon crystal, in which a single‐crystal silicon sphere of nearly perfect geometry is placed in a Fabry–Perot etalon of accurately known plate distance, and the diameters are obtained by measuring the two gaps between the etalon and the adjacent surface of the sphere. A new method is used to measure the sum of the length of the two gaps by scanning the etalon against the sphere. Two wavelengths, 633 nm from a frequency‐stabilized He–Ne laser and 441 nm from a free‐running He–Cd laser, are used to determine the order of interference by applying the method of exact fractions. The diameter of about 94 mm has been measured with a resolution of 0.5 nm. Diameter measurements from uniformly distributed directions have shown that the mean diameter has been determined with a standard deviation of 8.6 nm, corresponding to 0.28 ppm in the volume determination. The total uncertainty of the volume is estimated to be 0.34 ppm. Effects of a thin oxide layer and impurities on the bulk density are discussed.
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07.60.Ly Interferometers

Modulational sources, sideband correlations and nonstationary interference for waves scattered from random mediaa)

Raffi Nazikian

Rev. Sci. Instrum. 63, 5326 (1992); http://dx.doi.org/10.1063/1.1143448 (6 pages) | Cited 2 times

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For the small angle scattering of coherent plane waves from inhomogeneous random media, the three‐dimensional mean square distribution of random fluctuations may be recovered from the interferometric detection of the nonstationary modulational structure of the scattered field. Modulational properties of coherent waves scattered from random media are related to nonlocal correlations in the double sideband structure of the scattered field. To second order, such correlations may be expressed in terms of a suitably generalized spectral coherence function for analytic fields.
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41.20.Jb Electromagnetic wave propagation; radiowave propagation
52.40.Db Electromagnetic (nonlaser) radiation interactions with plasma

A reflectance anisotropy spectrometer for real‐time measurements

O. Acher and B. Drévillon

Rev. Sci. Instrum. 63, 5332 (1992); http://dx.doi.org/10.1063/1.1143398 (8 pages) | Cited 29 times

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A new reflectance anisotropy (RA) spectrometer, in the 0.23–0.83‐μm range, is presented. The numerous similarities with phase‐modulated ellipsometry (PME) are emphasized. In particular, the RA spectrometer takes advantage of the high‐frequency modulation (50 kHz) provided by a photoelastic modulator. The use of optical fibers in both optical arms allows an increase of the compactness of the spectrometer. Four detectors can be used simultaneously providing the real‐time spectroscopic capability. The numerical data acquisition system of the detected signal is based on the use of a high precision analog‐digital converter and a fast Fourier transform processor. However, as compared to ellipsometry, RA can be only sensitive to the crystal surface. The adaptation of RA to a III‐V growth reactor by metalorganic chemical vapor deposition is described in detail. The high sensitivity of the RA spectrometer is emphasized. In particular real‐time variations of the RA signal ranging from 10−4 to 10−3 are reported. Then, the various RA techniques are compared. In particular, it is shown that this RA spectrometer allows the determination of both the real and the imaginary part of the signal. Finally the origin of the RA signal is discussed.
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07.60.Rd Visible and ultraviolet spectrometers
07.60.Hv Refractometers and reflectometers

Electro‐optic tensor of KTiOPO4 measured with a Fizeau interferometer

B. L. Wang and X. Q. Liu

Rev. Sci. Instrum. 63, 5340 (1992); http://dx.doi.org/10.1063/1.1143399 (3 pages) | Cited 1 time

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A KTiOPO4 crystal block was used as a Fizeau interferometer. We modulated the interference pattern formed by the primary reflections from the front and rear surfaces of the crystal by the application of an electric field. The modulation is detected via a Faraday cell. In this way we measured the unclamped linear electro‐optic tensor with high precision.
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07.60.Ly Interferometers

Moderate resolution x‐ray reflectivity

J. D. Shindler and R. M. Suter

Rev. Sci. Instrum. 63, 5343 (1992); http://dx.doi.org/10.1063/1.1143400 (5 pages) | Cited 14 times

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We demonstrate that x‐ray reflectivity data covering eight decades of intensity can be obtained from a rotating anode source. Our moderate resolution configuration uses a bent graphite monochromator in contrast to the usual high resolution measurement which uses a silicon or germanium monochromator. Illustrative data show that moderate resolution is appropriate for probing a wide variety of surfaces and films. The availability in our configuration of roughly 100 times the incident intensity of a high resolution experiment using a laboratory source allows measurements over a broader angular range which in turn allows us to probe short length scale details of interface structure and tightens the constraints on models of interface structure. Both specular and diffuse scattering signals are accessible. A discussion of reciprocal space resolution explains why there is almost no difference in effective resolutions in the measurement of diffuse scattering.
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07.85.-m X- and γ-ray instruments
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.05.C- X-ray diffraction and scattering

NMR Fresnel transform imaging technique using a quadratic nonlinear field gradient

Yoshifumi Yamada, Kunio Tanaka, and Zenmon Abe

Rev. Sci. Instrum. 63, 5348 (1992); http://dx.doi.org/10.1063/1.1143401 (11 pages) | Cited 7 times

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A new NMR imaging technique using a quadratic nonlinear field gradient is described. The center position of the nonlinear field gradient where the field intensity is minimum is moved spatially at a fixed amount in each imaging pulse sequence to produce nonlinear phase encoding as a function of position. A NMR image is reconstructed from the collected data by the computer data processing. The principle of this technique and many experimental results using a low field imaging system operating at 0.0192 T are presented. Theoretical and experimental comparison of the S/N of the image in this technique with that of the conventional Fourier imaging technique are made and the results show that both techniques have almost the same S/N. Moreover, the theoretical and experimental results show that this technique has a feasibility of a spatially localized imaging without using a conventional localization technique such as the use of the selective excitation in the presence of a linear field gradient.
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87.61.-c Magnetic resonance imaging

NMR data acquisition, data processing, and spectrometer control with an IBM PC compatible

F. Humbert, A. Retournard, E. Mischler, J. Brondeau, and D. Canet

Rev. Sci. Instrum. 63, 5359 (1992); http://dx.doi.org/10.1063/1.1143402 (3 pages) | Cited 2 times

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This article describes a system implemented on an IBM compatible personal computer (PC) for acquisition and processing of NMR data and for the spectrometer control. The homemade hardware includes a 12‐bit analog‐digital conversion board and a simplified pulse sequence controller. The software, written in assembly language and in Turbo Pascal, handles these two boards and, thanks to a versatile pulse generator, allows easily to run most of the modern NMR experiments in simple or in quadrature detection with spectral widths up to 25 000 Hz. Owing to its simplicity, its low cost, and its versatility, this system is specially suited for upgrading old NMR spectrometers or can be considered as the basis of a routine spectrometer.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation

A cw electron nuclear double resonance resonator for single crystal studies

J.‐P. Willems, A. A. K. Klaassen, E. J. Reijerse, G. E. Janssen, and E. de Boer

Rev. Sci. Instrum. 63, 5362 (1992); http://dx.doi.org/10.1063/1.1143403 (4 pages) | Cited 1 time

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The design of an electron nuclear double resonance (ENDOR) resonator suitable for single crystal studies is reported. An outline is given of the mechanical and electronic construction of the resonator. This paper will focus on the construction suitable for studies at 4.2 K, but the design can be easily adapted to a flow cryostat for variable temperature measurements. The rf‐coil efficiency has been measured and is high and fairly constant over the frequency range from 0.3 to 20 MHz. Measurements on a test compound, show that the baseline stability is good over this frequency range. Even for low abundant nuclei as 13C, the signal to noise ratio is very good.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
76.70.Dx Electron-nuclear double resonance (ENDOR), electron double resonance (ELDOR)

A new impedance spectrometer for the investigation of electrochemical systems

G. S. Popkirov and R. N. Schindler

Rev. Sci. Instrum. 63, 5366 (1992); http://dx.doi.org/10.1063/1.1143404 (7 pages) | Cited 40 times

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The development of a computer‐controlled electrochemical impedance spectrometer, based on a Fourier transform algorithm is described. Together with a fast potentiostat the system can be used in the frequency range 1 mHz to 100 kHz. The perturbation signal is a superposition of sine waves with properly chosen frequencies. The overall measurement time is limited only by the lowest frequency in the spectrum and by the data transfer to the computer, thus, time‐resolved impedance spectra measurements can be performed. The principle of operation and technical details are presented and discussed.
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82.45.-h Electrochemistry and electrophoresis
07.50.-e Electrical and electronic instruments and components

Attractive mode force microscopy using a feedback‐controlled fiber interferometer

M. Nonnenmacher, M. Vaez‐Iravani, and H. K. Wickramasinghe

Rev. Sci. Instrum. 63, 5373 (1992); http://dx.doi.org/10.1063/1.1143405 (4 pages) | Cited 2 times

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We present a force microscope which uses a feedback‐controlled differential fiber interferometer for the measurement of the deflection of the force‐sensing cantilever. Due to the differential principle, and the feedback control, the influence of thermal and mechanical drifts or fluctuations is minimized. Topographic images in both modes, the attractive ac mode and the repulsive dc mode, have been taken to demonstrate a first performance of the instrument.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
07.60.Ly Interferometers
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