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Jun 1990

Volume 61, Issue 6, pp. 1579-1760

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Microfabricated nonoptical chemical sensors

Jay N. Zemel

Rev. Sci. Instrum. 61, 1579 (1990); http://dx.doi.org/10.1063/1.1141174 (28 pages) | Cited 4 times

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In the past two decades, there has been growing interest in new types of chemically sensitive devices based on the photolithographic batch processing employed by the semiconductor industry. This article reviews several classes of chemical sensors including electrochemical devices based on potentiometry and amperometry, chemical sensors based on thermal processes, and acoustic wave devices. Devices based on dielectric property variation, the core of spectroscopy, are not treated here since many reviews of these topics are available. The article touches on the device principles and reviews some of the more recent developments in each class.
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85.40.Hp Lithography, masks and pattern transfer

High‐resolution pulsed dye laser calibration in the 500–350 nm region using iodine atlas reference lines

Dennis J. Clouthier and Jerry Karolczak

Rev. Sci. Instrum. 61, 1607 (1990); http://dx.doi.org/10.1063/1.1141122 (5 pages) | Cited 39 times

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A simple, inexpensive method for precisely calibrating high resolution, pulsed dye lasers in the 500–340‐nm wavelength region has been devised. The residual portion of the laser beam exiting from an experiment is Raman shifted to longer wavelnegths in a high‐pressure hydrogen cell. The Stokes shifted output is used to excite laser induced fluorescence (LIF) signals in I2 vapor, which, in turn, are used to accurately calibrate the wavelength of the Raman shifted beam. The constant Raman shift, which can be precisely calculated, is then added to give the original laser wavelength. The method is readily adapted to computerized data acquisition and gives results of comparable accuracy to those of I2 LIF calibrations in the conventional 850–500 nm region.
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42.55.Mv Dye lasers

A far infrared laser sideband spectrometer in the frequency region 550–2700 GHz

P. Verhoeve, E. Zwart, M. Versluis, M. Drabbels, J. J. ter Meulen, W. Leo Meerts, A. Dymanus, and D. B. McLay

Rev. Sci. Instrum. 61, 1612 (1990); http://dx.doi.org/10.1063/1.1141123 (14 pages) | Cited 21 times

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This paper describes a tunable far‐infrared (FIR) spectrometer. Tunable radiation is obtained by frequency mixing, fixed frequency FIR laser radiation and tunable microwave radiation in Schottky barrier diodes. An optically pumped laser and an HCN discharge laser are used as FIR sources and klystrons in the frequency range of 22–114 GHz as microwave sources. This yields an 85% coverage of the frequency region between 550 and 2700 GHz. Up to sixth order sidebands have been generated and used for spectroscopy. The ultimate sensitivity corresponds to a minimum detectable fractional absorption of 105 at 1‐s RC time. The applicability of the spectrometer in high‐resolution spectroscopy of transient species has been demonstrated by the observation of spectra of OD and N2H+. New laser emissions of optically pumped CH2F2 have been found and accurate frequencies have been determined for some of them.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques

Low pass filter for soft x‐ray monochromators

L. J. Terminello, A. B. McLean, A. Santoni, E. Spiller, and F. J. Himpsel

Rev. Sci. Instrum. 61, 1626 (1990); http://dx.doi.org/10.1063/1.1141124 (3 pages) | Cited 5 times

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A low pass filter is described that suppresses higher‐order diffraction light from vacuum ultraviolet and soft x‐ray monochromators. It consists of a triple silicon reflector with the angle of incidence matched to the desired photon energy cutoff. The performance is calculated and tested experimentally using a toroidal grating monochromator.
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07.85.-m X- and γ-ray instruments

Computer‐based controller and averager for the Balle‐Flygare spectrometer

C. Chuang, C. J. Hawley, T. Emilsson, and H. S. Gutowsky

Rev. Sci. Instrum. 61, 1629 (1990); http://dx.doi.org/10.1063/1.1141125 (7 pages) | Cited 39 times

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A computer‐based controller/averager has been built for the Balle‐Flygare pulsed nozzle, Fourier transform, microwave spectrometer. We have integrated gas and microwave pulse control, digitizing and averaging, signal processing, and mirror and frequency control into an IBM PC‐AT, allowing the computer to coordinate all processes in the spectrometer. Multiple free induction decays (FIDs) are recorded for a single gas pulse without delay between digitizing sequences by continuously clocking the FID’s into multiple segments of digitizer memory. The averager fits into one of the AT’s expansion slots and has the unique feature of sharing 16 kbyte of static memory with the CPU. This gives the computer immediate access to the current average since it is already in the computer’s memory. The averaging is very fast so that the nozzle and vacuum pump remain the limiting factors for the repetition rate. Programming features are described. The spectrometer is now easier and faster to run. The increased speed and multiple FIDs per gas shot improve the signal‐to‐noise ratio, thus improving the chances of finding weak transitions. It is possible now to make automated searches for new transitions.
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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)
33.20.Bx Radio-frequency and microwave spectra

Ultrahigh vacuum picosecond laser‐driven electron diffraction system

H. E. Elsayed‐Ali and J. W. Herman

Rev. Sci. Instrum. 61, 1636 (1990); http://dx.doi.org/10.1063/1.1141126 (12 pages) | Cited 34 times

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A laser‐driven picosecond time‐resolved electron diffraction system operating in ultrahigh vacuum is described. A picosecond laser pulse is split into two beams. The first interacts with the sample under study. The second activates the cathode of an electron gun creating a collimated and focused electron pulse that is well synchronized with the heating laser pulse. By spatially delaying the part of the laser pulse that photoactivates the cathode from that which irradiates the sample, the electron pulse can be set to arrive at the sample at a specific time after sample irradiation. When a flat smooth sample is aligned such that the electrons are in grazing incidence on its surface, a reflection high‐energy electron diffraction pattern of its first few atomic layers is generated. Analysis of the diffraction pattern provides information on the surface structure and temperature at a set time lapse between the arrival of the laser and the electron pulse to the sample. Design, characterization, and operation of this system along with an example of its application to monitor the transient surface temperature using the surface Debye–Waller effect are discussed.
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61.05.J- Electron diffraction and scattering
42.60.By Design of specific laser systems
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)

Low‐profile high‐efficiency microchannel‐plate detector system for scanning electron microscopy applications

Michael T. Postek, William J. Keery, and Nolan V. Frederick

Rev. Sci. Instrum. 61, 1648 (1990); http://dx.doi.org/10.1063/1.1141127 (10 pages) | Cited 6 times

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A new design high‐efficiency microchannel‐plate detector and amplification system is described for use in the scanning electron microscope. This complete detector system consists of four basic units: (1) the microchannel‐plate detector; (2) the video amplifier; (3) the high‐voltage power supply; and (4) the control unit. The microchannel‐plate detector system is efficient at both high and low accelerating voltages, and is capable of both secondary electron and backscattered electron detection modes. The size of the actual detector is approximately 3.5 mm in thickness and 25.4 mm in diameter. Thus, use of this detector system permits using almost all the sample chamber to accommodate large specimens with only the loss of the 3.5 mm of working distance. Another feature is that this system also employs a unique video amplifier where there are no active elements at high voltage. The microchannel‐plate detector system enables the investigation of secondary electron induced contrast mechanisms and backscattered electron detection at extremely low accelerating voltages even those below 1.0 keV.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers

A simple endoscopic automatic vision system applied to monitoring of adhesive bonding

K. T. V. Grattan, Y. N. Ning, A. W. Palmer, and N. D. Fox

Rev. Sci. Instrum. 61, 1658 (1990); http://dx.doi.org/10.1063/1.1141128 (6 pages)

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A simple, endoscopic automatic vision system, using white‐light illumination has been designed and is discussed. Results of an application to the monitoring of the laying of an adhesive strip in a robotically operated product assembly are illustrated.
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81.90.+c Other topics in materials science (restricted to new topics in section 81)

A scanning tunneling microscopy/spectroscopy system for cross‐sectional observations of epitaxial layers of semiconductors

Takashi Kato and Ichiro Tanaka

Rev. Sci. Instrum. 61, 1664 (1990); http://dx.doi.org/10.1063/1.1141129 (4 pages) | Cited 3 times

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We have constructed a new scanning tunneling microscope (STM) using two mechanical stages. One (z stage) is for approaching the tip to the sample surface and the other (x stage) is for one‐dimensional movement of the sample to observe a specific area of the sample surface. The stages move so precisely that the distance between the tip and the sample is constant during the sample movement. It enables us to find the specific area quickly. Another feature of the STM is a novel data accessing method which realizes high‐speed scanning tunneling spectroscopy (STS) measurement. A great deal of data are accessed at high speed by a personal computer equipped with 32‐megabyte random access memory (RAM). Using this system, STM and STS measurements of cleaved (110) surfaces of Ga0.47In0.53 As/InP multiquantum wells were performed in air.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

A multiprocessor data acquisition and analysis system for scanning tunneling microscopy

A. J. Hoeven, E. J. van Loenen, P. J. G. M. van Hooft, and K. Oostveen

Rev. Sci. Instrum. 61, 1668 (1990); http://dx.doi.org/10.1063/1.1141130 (6 pages) | Cited 7 times

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A new data acquisition and analysis system for scanning tunneling microscopy has been developed. With a single system, topography studies and current imaging tunneling spectroscopy can be performed, nanometer‐scale indentations can be made, and the off‐line analysis can be done. The system is based on the parallel use of several processors allowing for simultaneous data acquisition, processing, and display. User interfacing is done only via a host computer, a UNIX system with three‐dimensional display capabilities, while the measurements and indentations are done via a second processor with optimal real‐time characteristics.
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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
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 Fourier transform mass spectrometer for surface analysis by laser‐induced thermal desorption of molecular adsorbates

Donald P. Land, Claire L. Pettiette‐Hall, Dirk Sander, Robert T. McIver, and John C. Hemminger

Rev. Sci. Instrum. 61, 1674 (1990); http://dx.doi.org/10.1063/1.1141131 (11 pages) | Cited 11 times

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A Fourier transform mass spectrometer (FTMS) for ultrahigh‐vacuum surface studies is described. The instrument incorporates standard surface analysis techniques such as Auger electron spectroscopy (AES), low‐energy electron diffraction (LEED), and Ar ion sputtering, along with laser‐induced thermal desorption (LITD) and thermal desorption spectroscopy (TDS) using FTMS detection, to perform surface analysis of metal samples. The manipulator allows temperature control of the samples between 110 and 1300 K. Using the LITD/FTMS surface reaction intermediates and kinetics are studied for the dehydrogenation of ethylene and cyclohexane on Pt(111). Relative sensitivities between AES and LITD/FTMS are discussed.
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07.75.+h Mass spectrometers
68.35.Dv Composition, segregation; defects and impurities

Fast bevel cross sectioning of quantum‐well semiconductor layers with high resolution

M. Honsberg

Rev. Sci. Instrum. 61, 1685 (1990); http://dx.doi.org/10.1063/1.1141132 (4 pages) | Cited 2 times

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An improved bevel cross‐sectioning method is presented which makes it possible to measure the thickness of relatively thin semiconductor surface layers. A staining procedure to enhance the contrast of the layers for two material systems, GaAs/GaAlAs and InP/InGaAsP, has been developed. Applying a newly constructed ball‐lapping‐apparatus, an ordinary optical microscope and a surface‐profiler, relatively thin MBE‐grown quantum‐well layers (6.5 nm) can rapidly be measured with an accuracy of better than 10%, which is improved for thicker, normal layers (1000 nm) to better than 5%.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Generation of controllable monodispersed sprays using impulse jet and charging techniques

Kyung‐Jin Choi and Brian Delcorio

Rev. Sci. Instrum. 61, 1689 (1990); http://dx.doi.org/10.1063/1.1141133 (5 pages) | Cited 9 times

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A technique for producing a tunable monodispersed spray is developed with a combination of impulsed jet and charging techniques. A single orifice impulse‐jet droplet generator, of a unique configuration, was used to produce a single stream of uniform droplets over a wide range of diameters. The single stream of droplets is dispersed with an electrostatic charging technique. Control of drop number density was enhanced by a droplet selection technique, in which a number of drops could be removed from the spray.
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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)
47.27.wg Turbulent jets

Effect of primary electron distribution on ion species yield in an ion source

Kazuhiro Watanabe, Masanori Araki, Masayuki Dairaku, Hiroshi Horiike, Yoshihiro Ohara, Yoshikazu Okumura, Shigeru Tanaka, and Kenji Yokoyama

Rev. Sci. Instrum. 61, 1694 (1990); http://dx.doi.org/10.1063/1.1141134 (5 pages) | Cited 8 times

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Effect of primary electron distribution on ion species yield is studied using a semicylindrical, multicusp plasma generator. Experimentally obtained, ion species yields were correlated with primary electron orbits estimated by computer simulation in several magnetic field configurations, where primary electron distributions were considered to be different. The result showed that a magnetic field configuration which produced lower proton yield had denser primary electron orbits in the neighborhood of the plasma grid. The floating potential of the plasma grid was also measured to suppose a distribution of the primary electrons. As a result, the proton yield increases with an increase of the floating potential of the plasma grid. These results lead us to confirm that the proton yield is determined by distribution of the primary electrons in the neighborhood of the plasma grid, in addition to the ratio of the plasma volume and the effective ion loss area. The highest proton yield of 93% and the lowest proton yield of 83% were obtained at the floating potential of the plasma grid of −5 and −21 V with respect to the anode potential, respectively, at an extraction current density of 150 mA/cm2.
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52.55.Fa Tokamaks, spherical tokamaks

Diagnostics with charged fusion products in ASDEX

Hans‐Stephan Bosch

Rev. Sci. Instrum. 61, 1699 (1990); http://dx.doi.org/10.1063/1.1141135 (9 pages) | Cited 6 times

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A diagnostic for measuring the spectra of 3‐MeV protons and 1‐MeV tritons from DD fusion reactions in a tokamak has been developed. The emphasis in this work was on obtaining an energy resolution high enough to get information on the ion energy distribution from the energy spectra of the charged fusion reaction products. This low‐noise system allowed the first direct measurement of the spectra of 1‐MeV tritons from a tokamak. The diagnostic system is described, and measurements of the ion temperature and spectra resulting from non‐Maxwellian ion distributions are presented. Rotating the detector from shot to shot to get different lines of sight, it is even possible to obtain an emission profile of the fusion reaction products.
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52.55.Fa Tokamaks, spherical tokamaks
28.52.-s Fusion reactors

A hyperbolic energy analyzer

Edbertho Leal‐Quiros and Mark A. Prelas

Rev. Sci. Instrum. 61, 1708 (1990); http://dx.doi.org/10.1063/1.1141136 (5 pages) | Cited 2 times

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The hyperbolic energy analyzer (HEA) is based on a novel diagnostic principle which uses a new type of electrostatic lens. The HEA has a pinhole aperture, a hyperbolic lens, and a long Faraday cup. The hyperboloid cones which make up the lens have a vertex angle of 70.53°. Each cone is held at a constant potential. The hyperbolic lens performs two functions: it focuses the ions in space and it selects the ion energy which is collected by the Faraday cup. The HEA measured electron and ion characteristics in the M4X (modified Missouri magnetic mirror experiment) and the results were confirmed with Langmuir probes and ion energy analyzers.
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52.70.Ds Electric and magnetic measurements
28.52.Av Theory, design, and computerized simulation
52.55.-s Magnetic confinement and equilibrium

MEDEA II two‐pulse generator development

F. M. Bieniosek, J. Honig, and E. A. Theby

Rev. Sci. Instrum. 61, 1713 (1990); http://dx.doi.org/10.1063/1.1141137 (4 pages) | Cited 4 times

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This article discusses improvements in the efficiency, output power, and operational flexibility of MEDEA II, a double‐pulse electron beam accelerator at McDonnell Douglas Research Laboratories. A modified charging circuit, based on the triple‐resonance pulse transformer concept, was implemented on both of MEDEA II’s two stages. The output switches were modified to increase maximum output voltages, and a new, second output switch with asymmetric breakdown characteristics was developed. To avoid degradation of the second‐pulse output waveform at the diode, a keep‐alive circuit was installed. The effects of diode closure on double‐pulse operation are also discussed.
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41.75.Ht Relativistic electron and positron beams

Triple resonance pulse transformer circuit

F. M. Bieniosek

Rev. Sci. Instrum. 61, 1717 (1990); http://dx.doi.org/10.1063/1.1141138 (3 pages) | Cited 7 times

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A modified, resonant pulse transformer circuit, based on a generalization of the well‐known double‐resonance pulse transformer circuit, is described. This modified circuit allows complete energy transfer in the presence of non‐negligible internal capacitance of realistic pulse transformers, and substantially reduces peak transformer voltage, compared to the double‐resonance circuit. Conditions under which the internal capacitance significantly affects energy transfer, and sensitivity of overall efficiency to circuit component values are discussed.
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84.30.Sk Pulse and digital circuits
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Measurement of Allan variance and phase noise at fractions of a millihertz

Bruce L. Conroy and Duc Le

Rev. Sci. Instrum. 61, 1720 (1990); http://dx.doi.org/10.1063/1.1141139 (4 pages)

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Although the measurement of Allan variance of oscillators is well documented, there is a need for a simplified system for finding the degradation of phase noise and Allan variance step‐by‐step through a system. This article describes an instrumentation system for simultaneous measurement of additive phase noise and degradation in Allan variance through a transmitter system. Also included are measurements of a 20‐kW X‐band transmitter showing the effect of adding a pass tube regulator.
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04.30.-w Gravitational waves

Three‐axes sample manipulator for surface‐science experiments in ultrahigh vacuum

Y. Dai, H. Li, and F. Jona

Rev. Sci. Instrum. 61, 1724 (1990); http://dx.doi.org/10.1063/1.1141140 (5 pages) | Cited 8 times

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Additions to commercially available manipulators are described which allow independent rotations of a sample in ultrahigh vacuum around three mutually perpendicular axes, as well as in situ adjustments of the sample orientation with respect to any of the three rotation axes. The additions allow also the interchange of three different samples in situ, with no need for breaking the vacuum in the experimental chamber. The modified manipulator has been successfully tested in experiments involving low‐energy electron diffraction and photoemission with synchrotron light for either s or sp polarization geometries.
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73.90.+f Other topics in electronic structure and electrical properties of surfaces, interfaces, thin films, and low-dimensional structures (Restricted to new topics in section 73)

Simple, high‐voltage, square pulse generator for ion beam deflection in a neutron generator

Davor Tomić

Rev. Sci. Instrum. 61, 1729 (1990); http://dx.doi.org/10.1063/1.1141141 (4 pages) | Cited 2 times

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A fast rise time, low repetition rate, high‐voltage, square pulse generator with double‐diffused‐metal‐oxide‐semiconductor (DMOS) switching is described. It has been developed for ion beam deflection at an electrostatic deflector in a beam guide system of a neutron generator. The features of the generator are: 1.7 kV amplitude, variable frequency from 2 to 50 Hz, variable width from 0.5 to 5 μs, and 125 ns delay. Output pulses are free of overshoot and backswing with rise and fall times of approximately 45 ns and 5 μs width.
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84.30.Ng Oscillators, pulse generators, and function generators
41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams

Small, inexpensive apparatus for the determination of the density of powdered materials

M. Y. Chern, R. D. Mariani, D. A. Vennos, and F. J. DiSalvo

Rev. Sci. Instrum. 61, 1733 (1990); http://dx.doi.org/10.1063/1.1141142 (3 pages) | Cited 6 times

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An inexpensive apparatus for measuring the density of a small quantity of powdered material at an accuracy of 1% or better is presented. Since the working medium is a gas, the density of air or solvent sensitive samples can easily be measured with this apparatus in the ambient atmosphere of a glove box.
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06.30.Dr Mass and density
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation

Polymer film thickness measurement using laser‐ultrasound techniques

R. J. Dewhurst, L. Noui, and Q. Shan

Rev. Sci. Instrum. 61, 1736 (1990); http://dx.doi.org/10.1063/1.1141143 (7 pages) | Cited 9 times

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The thickness of thin polyester film has been measured using ultrasonic Lamb waves which were generated and detected using noncontacting laser techniques. The uncertainty analysis of such a measurement technique has been examined. Systematic errors in both time of flight and distance between laser generation and detection points were estimated and reduced with the assistance of computerized X‐scan translation techniques. Thickness measurements with uncertainties of less than 3% have been achieved.
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68.55.-a Thin film structure and morphology

A new pulse laser energy meter

Yipeng Yuan

Rev. Sci. Instrum. 61, 1743 (1990); http://dx.doi.org/10.1063/1.1141144 (4 pages) | Cited 1 time

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This article describes a new laser energy meter that converts light pressure to electromotive force. This meter has a sensitivity of 18.9 μV/J. For single‐pulse laser beam energy of a transverse, electric, atmospheric CO2 laser device, the measurement range is from 100 mJ to several joules. It is suitable to measure the energy of laser beam with ultrashort pulse to picosecond durations. The meter features fast response, short recovery time, and no interruption of the laser beam.
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07.60.Dq Photometers, radiometers, and colorimeters
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Atomic oxygen detection by a silver‐coated quartz deposition monitor

V. Matijasevic, E. L. Garwin, and R. H. Hammond

Rev. Sci. Instrum. 61, 1747 (1990); http://dx.doi.org/10.1063/1.1141145 (3 pages) | Cited 42 times

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A method for measuring the flux of atomic oxygen utilizing a silver film on a quartz‐crystal deposition rate monitor is described. Measuring the initial oxidation rate of the silver, which is proportional to the atomic oxygen flux, determines a lower limit on the atomic oxygen flux. This method is more direct than measuring the conductance of the silver film, has an intrinsic flux detection range of 1013–1017 atoms/cm2 s, and is reversible by exposing the sensor to an atomic hydrogen flux.
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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)
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