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Oct 1987

Volume 58, Issue 10, pp. 1789-1967

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Mass analyzed secondary ion microscopy

Mark T. Bernius and George H. Morrison

Rev. Sci. Instrum. 58, 1789 (1987); http://dx.doi.org/10.1063/1.1139523 (17 pages) | Cited 7 times

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This paper reviews and critically assesses progress in the field of surface and near‐surface imaging microscopies based on secondary ion mass spectrometry. The ion microscope performs a variety of analytical functions, including complete mass spectra and isotope ratios from areas on the submicron scale, and lateral distribution analysis using ion imaging, with high sensitivity for all elements of the periodic table. Recent developments have improved the ion microscope’s ability to image a specimen’s elemental morphology with spatial resolutions below 100 nm. Criteria for the quantitative evaluation of ion images and the instruments that produce them are reviewed within the framework of information‐transmission theory. A complete and general description of the physical principles guiding the types of instrumentation available is thus presented, with emphasis on the accuracy and precision of an analytical measurement. Several directions for future developments are proposed.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
06.30.-k Measurements common to several branches of physics and astronomy

Scanning tunneling microscope for low temperature, high magnetic field, and spatially resolved spectroscopy

A. P. Fein, J. R. Kirtley, and R. M. Feenstra

Rev. Sci. Instrum. 58, 1806 (1987); http://dx.doi.org/10.1063/1.1139524 (5 pages) | Cited 42 times

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A scanning tunneling microscope capable of operating at low temperatures, T=400 mK, and in high magnetic fields, B=8 T, is described. Accompanying electronics, under the control of an IBM PC/AT, provide routine spatially resolved spectroscopy, allowing characterization of properties such as superconducting energy gaps and local density of states on the surface. Data are presented to illustrate the usefulness of spatially resolved spectroscopy at low temperatures and in high magnetic fields.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
79.60.Dp Adsorbed layers and thin films
79.70.+q Field emission, ionization, evaporation, and desorption

Simple line‐sampling apparatus for line frequency stroboscopic observation of periodic phenomena using scanning electron microscopy

T. Ikuta, H. Mase, and R. Shimizu

Rev. Sci. Instrum. 58, 1811 (1987); http://dx.doi.org/10.1063/1.1139662 (6 pages) | Cited 1 time

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Detailed operations of the apparatus for the stroboscopic observation of periodic phenomena at the region of line frequencies, such as the magnetic domain response, under the scanning electron microscopy are described in this paper. To achieve the stroboscopic observation at such low frequencies, a new line‐sampling technique has been introduced instead of the conventional point‐sampling method. In addition to the line‐sampling stroboscopy, a multiframe operation is also introduced to display the stroboscopic images of different phase values simultaneously. These operations are simply realized by applying the raster separation and the blanking on the display monitor scope under the multiple line‐sampling during the one‐drive period. To demonstrate the ability of this simple apparatus, some results of the stroboscopic observation of magnetic domains in an Fe–Si sample under a 60‐Hz drive field are also presented in this paper.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
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

Using electron channeling patterns for the measurement of lattice parameters

A. E. Curzon and O. S. Rajora

Rev. Sci. Instrum. 58, 1817 (1987); http://dx.doi.org/10.1063/1.1139525 (5 pages) | Cited 3 times

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The positions of the lines seen in an electron channeling pattern depend on the type and orientation of the crystal producing the pattern and on the energy of the incident electron beam. It is possible to make three lines intersect at a point by altering the energy or equivalently the wavelength, λ, of the incident electrons. A mathematical expression, valid for all crystal classes, is derived for this wavelength in terms of the Miller indices and plane spacings of the Bragg planes which give rise to the three lines in question. The theory has been tested by using the hexagonal layer material NbSe2. The channeling lines whose Bragg planes are (22.0), (30.0), and (22.2) were found to intersect at λ=0.0098 nm which leads to a c spacing of c=1.26±0.01 nm. The x‐ray value is 1.254 nm. The analysis is formulated so that it can be used on a computer without graphics facilities.
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61.05.jd Theories of electron diffraction and scattering
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
79.20.Kz Other electron-impact emission phenomena

Quantitative assessment of a parallel detection system for energy‐loss spectrometry

Dale E. Johnson and Megan Connick

Rev. Sci. Instrum. 58, 1822 (1987); http://dx.doi.org/10.1063/1.1139526 (8 pages) | Cited 5 times

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The concept of a spatial frequency‐dependent, detective quantum efficiency [=DQE( f )] is applied to the performance assessment of a prototype parallel detection system for electron energy‐loss spectrometry. The various factors which determine DQE( f ) in such a system are discussed and comparisons are made with a serial detection system. Also, the effects of the electron source energy spread on the overall spectrometer DQE( f ) are discussed. In these examples, the clear importance of including the spatial frequency dependence of DQE is demonstrated.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
85.60.Dw Photodiodes; phototransistors; photoresistors
85.60.-q Optoelectronic devices

Deceleration ion optical system for sputtering measurements between 50 and 500 eV as function of angle of incidence

H. Liebl, J. Bohdansky, J. Roth, and V. Dose

Rev. Sci. Instrum. 58, 1830 (1987); http://dx.doi.org/10.1063/1.1139527 (3 pages) | Cited 11 times

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A deceleration system for a parallel ion beam in the energy range of 50 to 500 eV is described. The system is used for sputtering yield measurements as a function of the angle of ion incidence. Measured yield data for Cu and Au sputtered by 100‐ and 300‐eV D+ ions are reported and compared to computer calculations. Experimental and calculated data show only a weak dependence on the angle of incidence. However, at glancing incidence the experimental values are larger up to a factor of 2 compared to the calculated ones. This is attributed to the surface roughness not included in the calculations.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Single photon detection and timing system for a Lidar experiment

Maurizio Viterbini, Alberto Adriani, and Guido Di Donfrancesco

Rev. Sci. Instrum. 58, 1833 (1987); http://dx.doi.org/10.1063/1.1139528 (7 pages) | Cited 4 times

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An instrument for photon counting measurements in a Lidar experiment is described. Single events can be stored up to rates of 25 MHz and it is capable of 4096 data acquisitions for each measurement. Time information by two successive photons is achieved with an accuracy better than 14 ns. The system is interfaced with an HP 1000F series computer. A window discriminator/shaper for formatting the photomultiplier pulses is also described.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
42.68.Wt Remote sensing; LIDAR and adaptive systems
42.50.Ar Photon statistics and coherence theory

Repetitive subsecond fluorescence spectra and anisotropy measurements using an optical multichannel analyzer

David A. Deranleau and Edgar Stüssi

Rev. Sci. Instrum. 58, 1840 (1987); http://dx.doi.org/10.1063/1.1139529 (3 pages) | Cited 3 times

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A vidicon tube‐based optical multichannel analyzer (OMA) was interfaced to a minicomputer to facilitate the acquisition of real‐time light transmission (or fluorescence anisotropy), right‐angle scattering, and fluorescence spectra at subsecond rates. The apparatus was designed for kinetic studies of the optical responses of living cells to stimulation with physiological and other activators, and features menu‐driven interactive graphics for presentation and handling of the intensity, wavelength, and time data in two or three dimensions. Stimulus‐induced secretion of acriflavine‐loaded human blood platelet dense granule contents is shown as an example of the apparatus capabilities.
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87.80.-y Biophysical techniques (research methods)
87.50.S- Radiofrequency/microwave fields effects
87.50.W- Optical/infrared radiation effects
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

Minicomputer interface for magneto‐optic spatial light modulator

A. Knoesen, N. F. Hartman, T. K. Gaylord, and C. C. Guest

Rev. Sci. Instrum. 58, 1843 (1987); http://dx.doi.org/10.1063/1.1139530 (9 pages) | Cited 1 time

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Digital optical data storage and processing are rapidly increasing in technological importance. The magneto‐optic spatial light modulator (MOSLM) is a relatively low‐cost, small pixel optical parallel input device that is capable of binary amplitude or binary phase modulation of each pixel. Thus, it is well matched to digital optical coherent storage and processing technology. However, potential problems associated with its use include: lack of a design for a general minicomputer interface, lack of interactive data‐page file generation software, lack of ability to switch single pixels in some cases, lack of remote‐from‐computer operation capability, spurious pixel switching, and catastrophic failure due to thermal effects. The hardware and software components of a versatile minicomputer interface that has been successful in overcoming all of these problems are described. This interface allows easy data entry of entire data pages or single pixels and minimizes cross talk and noise developed over long cable lengths. In tests, the designed interface has produced highly stable operating characteristics.
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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
07.05.Bx Computer systems: hardware, operating systems, computer languages, and utilities
42.79.Hp Optical processors, correlators, and modulators
89.20.Ff Computer science and technology

Rapid‐scanning autocorrelator with extended scanning span for monitoring short optical pulses

Akira Watanabe, Hiroshi Saito, Takashi Tokizaki, Yuzo Ishida, and Tatsuo Yajima

Rev. Sci. Instrum. 58, 1852 (1987); http://dx.doi.org/10.1063/1.1139531 (4 pages) | Cited 6 times

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We have developed a low‐cost rapid‐scanning autocorrelator which enables us to monitor picosecond optical pulses up to almost 100 ps. To achieve wide‐scan range, each arm of a Michelson‐type interferometer is scanned 180° out of phase by using audio speakers, and also only one‐half of a full autocorrelation waveform of the pulses is observed. The present apparatus is usefully used to measure about 80‐ps pulses generated from a cw mode‐locked Nd:YAG laser.
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42.15.Eq Optical system design
42.87.-d Optical testing techniques
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Absolute scanning [NF(a1Δ)] and [NF(b1Σ)] diagnostic method for the N2F4+H2 system

Y. D. Jones

Rev. Sci. Instrum. 58, 1856 (1987); http://dx.doi.org/10.1063/1.1139532 (4 pages)

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The N2F4+H2 system is of interest for production of NF(a1Δ) as an energy‐transfer species. Past studies have been plagued with the difficult NF(a1Δ) quantitative measurement due to interferences from the close‐lying N2(B) and HF peaks. This paper deals with the development of a scanning diagnostic method to determine concentrations of NF(a1Δ) and NF(b1Σ) in the N2F4+H2 system and quantitative measurement of interferences with the diagnostic signal. The diagnostic method has been applied to a functioning high‐pressure, high‐temperature system.
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82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
82.50.-m Photochemistry
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Optical method for measuring uniform thickness of the order of 10 μm–1 mm of transparent solid and liquid films

Tetsuya Ohyama and Yasuhiko H. Mori

Rev. Sci. Instrum. 58, 1860 (1987); http://dx.doi.org/10.1063/1.1139533 (5 pages) | Cited 4 times

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An optical‐interference method is proposed for measuring the thickness of ‘‘fairly thick’’ films of transparent (or weakly absorbing) solid materials or liquids. It uses a laser beam with an incident angle, on the subject film, changing with time, causing an alternation of constructive and destructive interferences of beams reflected, respectively, at upper and lower surfaces of the film. The total irradiance of the beams interfering with each other is continuously detected and recorded. From the number of periodical changes of the irradiance during the change of the incident angle over a specified range we can readily calculate the thickness of the film. A simple apparatus has been designed and constructed to realize this method. It has been shown that the method is applicable to measurements of thicknesses of both solid and liquid films, provided the films are kept stationary enough.
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42.87.-d Optical testing techniques
07.60.Ly Interferometers
78.66.-w Optical properties of specific thin films

Automatic measurement of laser diode thermal impedance

S. R. Chinn and T. L. Whitman

Rev. Sci. Instrum. 58, 1865 (1987); http://dx.doi.org/10.1063/1.1139534 (6 pages)

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An automated procedure has been developed for data acquisition and analysis in the measurement of laser diode thermal impedance. This method is an extension of previous optical measurement techniques, and has the advantage of obtaining many data points in a short time interval. Standard commercial instrumentation is widely used, with many variants of the technique being possible.
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07.20.Dt Thermometers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.87.-d Optical testing techniques

Sensitive gas‐phase photoacoustic spectrometer with provision for simultaneous recording of absorption spectrum

G. Chakrapani, Putcha Venkateswarlu, Yerneni V. Rao, and M. C. George

Rev. Sci. Instrum. 58, 1871 (1987); http://dx.doi.org/10.1063/1.1139535 (8 pages)

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The design of a sensitive pulsed photoacoustic spectrometer system for studying media in gaseous phase in the visible and ultraviolet regions is described. The system provides for simultaneous recording of the laser absorption spectrum of the sample by measuring the radiation transmitted through the sample cell. A highly sensitive optogalvanic detection subassembly for recording the calibration spectrum and analog signal processing/averaging electronics including gated integrators also form part of the system. Typical sensitivities of detection are a few tens of picobar acoustic pressure disturbances induced through two‐photon absorption in iodine vapor in the sample cell and 0.1 pC charge fluctuation induced in the neon/uranium hollow cathode discharge through optogalvanic effect. Typical recordings of the photoacoustic, laser absorption, and two‐photon photoacoustic spectra of the saturated vapor of iodine at room temperature in the presence of air at atmospheric pressure are presented together with the optogalvanic calibration spectra.
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43.58.Kr Spectrum and frequency analyzers and filters; acoustical and electrical oscillographs; photoacoustic spectrometers; acoustical delay lines and resonators
51.70.+f Optical and dielectric properties
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)
51.40.+p Acoustical properties

Continuous and stopped flow EPR spectrometer based on a loop gap resonator

Wayne L. Hubbell, Wojciech Froncisz, and James S. Hyde

Rev. Sci. Instrum. 58, 1879 (1987); http://dx.doi.org/10.1063/1.1139536 (8 pages) | Cited 32 times

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A continuous and stopped flow EPR spectrometer based on a new loop gap resonator operating at X band is described. The important features of the instrument are: (1) very small amounts of material are consumed in both stopped and continuous flow modes of operation, (2) dead times on the order of 4 ms for stopped flow and 1 ms for continuous flow are realized with a very narrow age distribution in the sample compartment, and (3) the dead times and, hence, sample age are highly reproducible and independent of viscosity due to the use of a positive displacement syringe ram. The performance of the instrument is evaluated using the decay of ascorbate radical generated by Ce(iv) oxidation and reduction of nitroxides by ascorbic acid.
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33.35.+r Electron resonance and relaxation
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques

Polychromatic x-ray beam produced by a wiggler: A new dimension in x-ray diffraction at megabar pressures

Yogesh K. Vohra, Steven J. Duclos, Keith E. Brister, and Arthur L. Ruoff

Rev. Sci. Instrum. 58, 1887 (1987); http://dx.doi.org/10.1063/1.1139537 (4 pages) | Cited 3 times

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The wiggler provides a substantially higher flux of photons through a given collimator at high energies than is available from the bending magnet at the Cornell High Energy Synchrotron Source. This opens a new dimension in ultrapressure x-ray diffraction studies. Examples are shown in which a good diffraction pattern of gold at 112 GPa (1.12 Mbar) was obtained in 13 s and in which the diffraction pattern for primitive hexagonal silicon at 35 GPa using the beam from the wiggler contains twice as many peaks as is the case for the beam from the bending magnet.
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07.85.-m X- and γ-ray instruments
61.05.C- X-ray diffraction and scattering
62.50.-p High-pressure effects in solids and liquids
42.72.-g Optical sources and standards

Silicon photodiode detector for fluorescence EXAFS

Charles E. Bouldin, Richard A. Forman, and Michael I. Bell

Rev. Sci. Instrum. 58, 1891 (1987); http://dx.doi.org/10.1063/1.1139538 (4 pages) | Cited 9 times

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A large‐area silicon diode is used as a fluorescence detector for extended x‐ray absorption fine‐structure (EXAFS) measurements. A direct comparison of this diode detector relative to a gas ionization fluorescence detector is made. Advantages of the diode detector include: higher signal for a given photon flux (due to higher quantum efficiency), vacuum and cryogenic compatibility, freedom from microphonic noise, good linearity, extremely wide dynamic range, operation without high voltage or gas connections, very simple electronics, and low cost. A brief comparison with other detection methods for fluorescence EXAFS is given. Use of photodiodes for transmission EXAFS is discussed.
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61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
07.85.-m X- and γ-ray instruments
29.40.Cs Gas-filled counters: ionization chambers, proportional, and avalanche counters
29.40.Wk Solid-state detectors

New surface wave launchers for sustaining plasma columns at submicrowave frequencies (1–300 MHz)

M. Moisan and Z. Zakrzewski

Rev. Sci. Instrum. 58, 1895 (1987); http://dx.doi.org/10.1063/1.1139539 (6 pages) | Cited 29 times

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We describe new surface wave launchers intended to sustain plasma columns with high‐frequency (hf) power in the range of 1–300 MHz. This frequency range complements that of the existing surface wave plasma generators (surfatron and surfaguide launchers), which are best suited to operate in the microwave domain (≳300 MHz). With the addition of this new type of launchers, called Ro‐box, it is now feasible to achieve a surface wave produced plasma column at applied frequencies ranging from 1 MHz to 10 GHz. The possibility of using the same physical hf coupling mechanism (surface wave propagation) over such a broad frequency band is an unprecedented situation with hf produced plasmas. This is of interest for both fundamental and applied physics, as it allows frequency effect investigations and frequency optimization of plasma processes. The new devices can be made so that the wave‐launching and the impedance‐matching functions are physically separated, leading to a modular design, a feature that facilitates changing the plasma tube diameter and the operating frequency range. A further advantage of the new devices is that their launching section can be implemented around the discharge tube more compactly than with the other surface wave launchers.
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52.50.Dg Plasma sources
52.80.Pi High-frequency and RF discharges
52.50.Gj Plasma heating by particle beams
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Three‐dimensional computer simulation of ion beam scattering by an electrostatic reflector

M. Nakamura, K. Tsuruda, and H. Hayakawa

Rev. Sci. Instrum. 58, 1901 (1987); http://dx.doi.org/10.1063/1.1139663 (4 pages)

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A three‐dimensional computer model was used to study the scattering of a reflected lithium ion beam by an electrostatic reflector. Results show that for ion gun systems for active space plasma experiment applications, beam scattering of less than 1° can be attained with electrostatic reflectors.
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41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams

Lithium‐free scintillation glasses for fast‐neutron detection

J. R. Smith, R. K. Fisher, and J. S. Leffler

Rev. Sci. Instrum. 58, 1905 (1987); http://dx.doi.org/10.1063/1.1139487 (5 pages) | Cited 1 time

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In this article, we present observed characteristics of new lithium‐free scintillation glasses which have been developed to make time‐resolved measurements of the 14‐MeV neutron flux from deuterium plasmas. These measurements will yield information on the burnup of tritons in today’s deuterium plasmas and are needed to better predict the confinement and slowdown of alpha particles in future D–T burning plasmas. The new glasses were formulated to have good detection efficiency for 14‐MeV neutrons, and yet be insensitive to 2.5‐MeV and lower‐energy neutrons. The glass response to alpha, gamma, and neutron radiation is shown. The intrinsic neutron detection efficiency of the scintillation glass is seen to increase significantly as a function of neutron energy, providing the necessary discrimination against low‐energy neutrons. We discuss the reactions which determine the glass neutron response and suggest that this response is dominated at higher neutron energies by gamma rays created by neutrons inelastically scattering from oxygen present in the glass. For high‐energy neutron detection in the presence of excessive background gamma radiation, we discuss a new coincidence configuration of lithium‐free scintillation glass with NE213 liquid scintillator.
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29.40.Mc Scintillation detectors
61.80.Hg Neutron radiation effects

Development of a 1.5‐tonne niobium gravitational radiational antenna

P. J. Veitch, D. G. Blair, N. P. Linthorne, L. D. Mann, and D. K. Ramm

Rev. Sci. Instrum. 58, 1910 (1987); http://dx.doi.org/10.1063/1.1139488 (7 pages) | Cited 12 times

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A 1.5‐tonne Nb gravitational radiation antenna is described. Problems associated with a noncontacting magnetically levitated parametric upconverter transducer are discussed, and a system using a bonded microwave reentrant cavity and bonded mechanical impedance transformer is described and analyzed in detail. It is shown that such an antenna can be expected to achieve a noise temperature of ∼1 mK. An ultralow phase noise tunable microwave source for the transducer pump signal is described, as well as precision bonding techniques which yield a mechanical positioning accuracy of 10−6 m, and a reproducibility of 10−8 m.
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04.80.-y Experimental studies of gravity

Differential dielectric‐to‐density measurement for cryogenic fluids

F. F. Liu and S. W. H. Chow

Rev. Sci. Instrum. 58, 1917 (1987); http://dx.doi.org/10.1063/1.1139489 (9 pages)

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A high‐speed microprocessor‐based cryogenic fluid density instrumentation is developed based on the rigorous application of dielectric theory, using a dielectric susceptibility function in the application of molecular Clausius–Mossotti formula. The operating principle is formulated on a novel differential dielectric measurement approach with a new algorithm which provides for automatic adjustments for polarizability and stray capacitance changes. High‐precision digital density measurement is achieved over a wide range of fluid state ranging from supercritical, through subcritical to solid formation phases. Its conceptual development is examined in view of the interplay between theoretical arguments and engineering methodology.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
06.30.Dr Mass and density
67.90.+z Other topics in quantum fluids and solids (restricted to new topics in section 67)

Models of formation and erosion of a plasma column in a silicon surface‐barrier detector

Ikuo Kanno

Rev. Sci. Instrum. 58, 1926 (1987); http://dx.doi.org/10.1063/1.1139490 (7 pages) | Cited 5 times

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Quantitative models of the formation and erosion of the plasma column are presented. With the model of formation, the radius, volume, and surface area of the plasma column and the number and the density of the electron‐hole pairs are calculated. In the model of the erosion, the change of the dielectric quality of the plasma column due to the enlargement of its volume is considered to be the cause of the erosion. The internal electric field strength of the plasma column is determined as a function of time. With this model, plasma delays are estimated for alpha particle, 40Ar and 129Xe ions and are compared with other author’s experiments. Ideally the recombination effect should be calculated as a product of the recombination rate and the time interval of the plasma delay. However, it is estimated here using two parameters for the fission fragments from thermal‐neutron‐induced fission of 235U because of the lack of adequate experimental data.
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72.30.+q High-frequency effects; plasma effects
73.50.Mx High-frequency effects; plasma effects
29.40.Wk Solid-state detectors

Elimination of the induced current error in magnetometers using superconducting flux transformers

D. Dummer and W. Weyhmann

Rev. Sci. Instrum. 58, 1933 (1987); http://dx.doi.org/10.1063/1.1139491 (4 pages) | Cited 3 times

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The changing magnetization of a sample in a superconducting flux transformer coupled magnetometer induces a current in the transformer which in turn changes the field at the sample. This ‘‘image’’ field and the error caused by it can be eliminated by sensing the current in the loop and nulling it by feedback through a mutual inductance. We have tested the technique on the superconducting transition of indium in an applied magnetic field and shown that the observed width of the transition is greatly reduced by maintaining zero current in the flux transformer.
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85.25.-j Superconducting devices
07.55.-w Magnetic instruments and components
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Development of a high‐sensitivity, computer‐controlled titration calorimeter

P. A. Baisden, P. M. Grant, and W. F. Kinard

Rev. Sci. Instrum. 58, 1937 (1987); http://dx.doi.org/10.1063/1.1139492 (5 pages) | Cited 6 times

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A highly sensitive, adiabatic titration calorimeter controlled by a personal computer is described. Operation of the entire calorimetric titration is automated, including the thermoelectric offset of the heat of stirring, the electrical calibration of the heat capacity, the addition of titrant, and the measurement of the heat of reaction. The average uncertainty in heat measurements was ≊±0.003 J for titrant additions generating 0.025 to 1.0 J of heat change in a 50‐ml sample. Calibration of the calorimeter using tris‐(hydroxymethyl) aminomethane [TRIS] gave excellent agreement with previously published values.
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07.20.Fw Calorimeters
82.80.-d Chemical analysis and related physical methods of analysis
82.60.Cx Enthalpies of combustion, reaction, and formation
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