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Dec 1985

Volume 56, Issue 12, pp. 2199-2339

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Use of an optical multichannel analyzer for recording absorption spectra of short‐lived transients

E. P. L. Hunter, M. G. Simic, and B. D. Michael

Rev. Sci. Instrum. 56, 2199 (1985); http://dx.doi.org/10.1063/1.1138398 (6 pages) | Cited 7 times

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Characteristics of an adapted commercial optical multichannel analyzer system for recording of transient absorption spectra in single‐shot pulse radiolysis and flash photolysis are described. The features discussed include temporal (2 μs) and spectral (1 nm) resolution, signal‐to‐noise ratio and its improvement, linearity of response, and wavelength coverage (300–650 nm). The system is intermediate in both cost and capabilities compared to two other methods: (1) recording transient spectra by repetitive pulsing and (2) using an image converter streak camera. This system is convenient for discrimination of small differences in fine structured absorption of spectra short‐lived species.
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07.60.Rd Visible and ultraviolet spectrometers
82.50.-m Photochemistry
82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

High‐resolution picosecond transient absorption spectrometer utilizing dye emission and a streak camera

Du‐Jeon Jang and David F. Kelley

Rev. Sci. Instrum. 56, 2205 (1985); http://dx.doi.org/10.1063/1.1138399 (4 pages) | Cited 6 times

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A high‐resolution picosecond transient absorption spectrometer utilizing dye emission and a streak camera is presented and compared with other methods of picosecond transient absorption measurements. Typical transient absorption and ground‐state bleach recovery kinetics measured with this spectrometer are shown. Single wavelength transient absorption or ground‐state bleach recovery kinetics are determined on the basis of a single laser shot with this spectrometer, so that the samples are relatively free from decomposition by irradiation. Excellent kinetics may be obtained from the near UV to the near IR and are not subject to interference from luminescence of samples. The sensitivity of this spectrometer is very high and it is reasonably easy and convenient to set up and use.
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07.60.Rd Visible and ultraviolet spectrometers
82.50.-m Photochemistry
82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Spatially resolved matrix isolation spectroscopy I: Visible spectra

Valerie I. Lang and John S. Winn

Rev. Sci. Instrum. 56, 2209 (1985); http://dx.doi.org/10.1063/1.1138400 (4 pages)

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An apparatus is described for measuring visible absorption spectra across the lateral dimension of a cryogenic matrix isolation sample. By exploiting the rigidity of the matrix, the spatially resolved spectra can be parametrically labeled by another experimental variable, such as photolysis wavelength from dispersed radiation, resulting in a multiplex advantage in data collection rates. Alternatively, the apparatus can be used to measure the visible absorption spectrum of a spatially uniform sample in ≤1 second, a speed which is important for photochemically active samples.
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07.60.Rd Visible and ultraviolet spectrometers
78.40.-q Absorption and reflection spectra: visible and ultraviolet

Measurements of density, surface recombination coefficient, and diffusion coefficient of hydrogen atoms by Lα laser fluorescence spectroscopy

Toshinori Kajiwara, Masayuki Inoue, Tatsuo Okada, Katsunori Muraoka, Masanori Akazaki, and Mitsuo Maeda

Rev. Sci. Instrum. 56, 2213 (1985); http://dx.doi.org/10.1063/1.1138401 (4 pages) | Cited 14 times

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The technique of laser fluorescence spectroscopy at the Lyman‐alpha (Lα) wavelength in hydrogen was used to measure the temporally and spatially resolved atomic density, the surface recombination coefficient γ, and the diffusion coefficient DH,H2 of the atomic hydrogen in molecular hydrogen. At the same time, it revealed a temporal change of γ, probably due to the change of surface number density of trapped hydrogen atoms. The present technique provides a new and powerful means for determinations of values associated with hydrogen atoms by absolute and local measurements of the atoms at the detection limit of extremely low concentrations.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
51.20.+d Viscosity, diffusion, and thermal conductivity
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.80.Dx Analytical methods involving electronic spectroscopy
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Rotating mirror device for nonresonant laser Raman difference spectroscopy

J. C. Martin

Rev. Sci. Instrum. 56, 2217 (1985); http://dx.doi.org/10.1063/1.1138402 (5 pages) | Cited 2 times

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A novel sample switching device for laser Raman difference spectroscopy (LRDS) has been designed for use with nonresonant samples. The device utilizes a single motor driven rotating mirror, fabricated by diamond turning techniques, which switches both exciting and scattered light 60 times per second. Electronic timing signals are obtained to gate photon counting pulses into separate scalers. The use of fixed capillary sample cells allows for the first time in LRDS the examination of fibers, single crystals, and liquid samples of 10‐μl volume and improved access to samples for thermostating, etc. Alignment of the optics is described. Proper operation of the system is illustrated by examination of pyridine and pyridine‐d5. Comparing spectra of the neat liquids and a mixture of them gives examples of a frequency shift of <1 cm−1, a width change, and other bands with no changes. Advantages, limitations, and future extensions of the instrument are described.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
42.79.-e Optical elements, devices, and systems
78.30.-j Infrared and Raman spectra
87.15.B- Structure of biomolecules

Polarization modulation ellipsometry: A compact and easy handling instrument

E. Huber, N. Baltzer, and M. von Allmen

Rev. Sci. Instrum. 56, 2222 (1985); http://dx.doi.org/10.1063/1.1138403 (6 pages) | Cited 5 times

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A polarization modulation ellipsometer for measurements of the complex dielectric function of opaque and reflecting materials in the wavelength range 230–920 nm is presented. The instrument can be built at relatively moderate cost but offers reasonable accuracy. It is suitable for routine measurements in a general solid‐state laboratory because of its easy handling and maintenance.
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07.60.Fs Polarimeters and ellipsometers
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
77.22.Ch Permittivity (dielectric function)

Imaging differential polarization microscope with electronic readout

William Mickols, Ignacio Tinoco, Joseph E. Katz, Marcos F. Maestre, and Carlos Bustamante

Rev. Sci. Instrum. 56, 2228 (1985); http://dx.doi.org/10.1063/1.1138354 (9 pages) | Cited 9 times

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A differential polarization microscope forms two images: one of the transmitted intensity and the other due to the change in intensity between images formed when different polarizations of light are used. The interpretation of these images for linear dichroism and circular dichroism are described. The design constraints on the data acquisition systems and the polarization modulation are described. The advantage of imaging several biological systems which contain optically anisotropic structures are described.
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07.60.Pb Conventional optical microscopes
87.80.-y Biophysical techniques (research methods)

New polarization‐modulation spectrometer for simultaneous circular dichroism and optical rotary dispersion measurements (I): Instrument design, analysis, and evaluation

Yohji Shindo and Yasuhiro Ohmi

Rev. Sci. Instrum. 56, 2237 (1985); http://dx.doi.org/10.1063/1.1138355 (6 pages) | Cited 5 times

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The Mueller matrix approach is used for designing, analyzing, and evaluating a new polarization‐modulation spectrometer for simultaneous measurements of circular dichroism (CD) and optical rotatory dispersion (ORD). The same approach is applied to commercial CD spectropolarimeters for the evaluation of their performance in order to clarify our new spectrometer. On the basis of the results obtained, our JASCO J‐500 CD spectropolarimeter was converted into the new spectrometer. Preliminary experiments indicate that CD and ORD can be measured simultaneously above 400 nm. It is also shown that this new spectrometer can be used for measuring linear dichroism and linear birefringence simultaneously.
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07.60.Rd Visible and ultraviolet spectrometers
07.60.Fs Polarimeters and ellipsometers

Application of diode array spectrometers in microscope photometry

Klaus‐P. Koch, Meinrad Maechler, and Franz Glueck

Rev. Sci. Instrum. 56, 2243 (1985); http://dx.doi.org/10.1063/1.1138356 (5 pages) | Cited 1 time

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Multichannel fast scanning diode array spectrometers represent a new class of spectroscopic instruments. They feature a unique combination of novel technologies, speed, comfort in handling, and ease of operation. In a research study the potentials of this powerful instrument in the field of microscope photometry are evaluated. As examples for possible applications the results of typical spectral measurements in absorption and reflection, including film‐thickness determination of microstructured semiconductor layers, are presented.
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07.60.Rd Visible and ultraviolet spectrometers
07.60.Dq Photometers, radiometers, and colorimeters
07.60.Pb Conventional optical microscopes
75.20.Ck Nonmetals

Simple and compact neutral metal vapor laser assembly operating in a low‐temperature region

Hiroshi Saito, Hiroshi Taniguchi, Hajime Nozawa, and Ken‐ichi Owashi

Rev. Sci. Instrum. 56, 2248 (1985); http://dx.doi.org/10.1063/1.1138357 (3 pages) | Cited 3 times

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A compact and inexpensive technique is reported for a discharge‐excited pulsed metal vapor laser (MVL) at a low operating temperature utilizing an air‐blown‐type spark‐gap switch. A laser is excited in an aperiodic pulse train by successive pulsed discharges of a storage capacitor through a spark‐gap switch. A variety of neutral metal vapor laser (MVL) using metal compound as a lasant is briefly reported with the compact device.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.By Design of specific laser systems

TEA CO2 laser with a SiC anode

D. Beaupere, G. Helias, and A. Bettinger

Rev. Sci. Instrum. 56, 2251 (1985); http://dx.doi.org/10.1063/1.1138358 (2 pages) | Cited 1 time

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It is demonstrated that the use of a SiC plane anode and a Dumanchin–Farcy type cathode in the TEA CO2 laser system yields very uniform glow discharges producing high specific peak power.
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42.60.By Design of specific laser systems
42.55.Lt Gas lasers including excimer and metal-vapor lasers
52.80.Hc Glow; corona

Large aperture, high‐speed calorimeter for high‐energy optical pulses

M. Niimura, J. Dooling, R. L. Zich, R. N. Brock, and T. M. York

Rev. Sci. Instrum. 56, 2253 (1985); http://dx.doi.org/10.1063/1.1138359 (6 pages) | Cited 1 time

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A radiometric calorimeter is described in which the energy absorber works at the same time as a temperature sensor so that thermal equilibrium for the entire volume of absorber is not required before measuring an incident energy. The achievable frequency response is therefore quite high, and this is not offset by the size and/or damage threshold of energy receiver. The device, formerly called Rat’s Nest Calorimeter (RNC), has been found quite useful for measuring the total energy of modern pulsed lasers with a large beam cross section. The aperture (presently 6 cm) can be increased arbitrarily without degrading the rise time. Excellent stability and high damage threshold (≫439 MW/cm2) result when a thick wire bolometer and amplifier combination is used. Response time (∼9 μs) and spectral flatness are much better than previously reported. Potentials of the RNC for measuring any energy which it absorbs up to 2 kJ at the rise time 60 ns (∼10 MHz) are discussed. The maximum sensitivity of the model 3.5 mJ/cm2 is sufficient to detect the radiative energy emitting from today’s fusion test plasmas.
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07.20.Fw Calorimeters
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Microcomputer‐based spectrum‐resolved second‐harmonic generation correlator for fast measurement of ultrashort pulses

Akira Watanabe, Shosaku Tanaka, Hiroshi Kobayashi, Yuzo Ishida, and Tatsuo Yajima

Rev. Sci. Instrum. 56, 2259 (1985); http://dx.doi.org/10.1063/1.1138360 (4 pages) | Cited 3 times

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A new spectrum‐resolved second‐harmonic generation correlator using a single‐line image sensor array and a microcomputer has been developed. It allows us acquisition of many spectrum‐resolved second‐harmonic generation correlation traces in a single scan of the optical delay. Using this correlator, the pulse properties of a colliding pulse mode‐locked ring dye laser have been investigated. It was found that the measuring time can be reduced by an order of magnitude compared with the conventional repeat‐scan method.
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42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.-e Optical elements, devices, and systems
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.55.Mv Dye lasers

Fast heterodyne interferometer with electronically stabilized initial phase

C. A. J. van der Geer, A. F. G. van der Meer, and W. J. Mastop

Rev. Sci. Instrum. 56, 2263 (1985); http://dx.doi.org/10.1063/1.1138361 (4 pages) | Cited 1 time

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A heterodyne interferometer setup with initial‐phase stabilization is described, which allows the full range of ‘‘half a fringe’’ to be used without ambiguity, using only one phase comparator. This phase stabilization is achieved by the insertion of a voltage‐controlled delay line in the reference path of the phase comparator. The system is used to measure the electron line density of pulsed plasmas (with pulse lengths of 1 ms) in the range 5×1019–2×1021 m−2 with a time resolution of 200 ns. The resolution of the electronic system is approximately (half a fringe)/200.
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07.60.Ly Interferometers
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Data acquisition and instrument control system for ion flight time measurements in mass spectrometry

J. T. Stults, C. A. Myerholtz, B. H. Newcome, C. G. Enke, and J. F. Holland

Rev. Sci. Instrum. 56, 2267 (1985); http://dx.doi.org/10.1063/1.1138362 (7 pages) | Cited 3 times

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A microcomputer system is described that provides instrument control and data acquisition for ion flight time measurements in mass spectrometry. This system is designed specifically for time‐resolved ion momentum spectrometry (TRIMS), a new mass spectrometry/mass spectrometry (MS/MS) technique that utilizes time‐of‐flight measurements in a magnetic sector instrument. The flexibility of the design, however, makes it applicable to many types of instruments that employ ion flight time measurements. The heart of the system is a digital boxcar integrator with 10‐ns timing precision. The microcomputer has control of both the magnetic field and the sampled flight time. Software, written in forth, allows all standard MS/MS scans to be obtained, even those requiring complex linked scans of the magnetic field strength and the sampled flight time. Data that demonstrate the accuracy of these scans are shown for metastable decompositions of n decane.
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07.75.+h Mass spectrometers
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
07.07.Tw Servo and control equipment; robots
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Extraction of volume‐produced H− ions from a hybrid magnetic multicusp source

M. Bacal and F. Hillion

Rev. Sci. Instrum. 56, 2274 (1985); http://dx.doi.org/10.1063/1.1138363 (5 pages) | Cited 8 times

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The negative ion density n− is studied using the photodetachment technique in the extraction region of a 5.7‐l hybrid magnetic multicusp source, and is correlated with the extracted negative ion current I−. It is found that biasing positive the plasma electrode (PE) of the extractor affects in a similar way both n− and I−: both attain a maximum for a PE bias of +1.5 V, while the electron density ne and extracted current Ie exhibit a monotonic reduction. At optimum PE bias, n−/ne attains a value of 0.7. Ie is found to be comparable to the electron thermal flux through the extraction slit; this indicates that there is no potential barrier for the negative particles at the plasma border in front of the extraction slit. At optimum PE bias both Ie and I− vary in proportion to n0.8e. Two regimes characterize the variation of I− vs n−; at high density I− varies in proportion to n1− and appears to be larger than the thermal negative ion flux through the extraction slit, calculated under the assumption that the negative ion temperature is close to the neutral molecule temperature. The discrepancy is the largest (a factor of ten) at the lowest gas pressure.
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29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
52.50.Dg Plasma sources
52.55.Lf Field-reversed configurations, rotamaks, astrons, ion rings, magnetized target fusion, and cusps

Time‐resolved measurement of energy and species of an intense pulsed ion beam

T. Matsuzawa, A. Takahashi, K. Masugata, M. Ito, M. Matsui, and K. Yatsui

Rev. Sci. Instrum. 56, 2279 (1985); http://dx.doi.org/10.1063/1.1138364 (4 pages) | Cited 8 times

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A time‐resolvable Thomson‐parabola spectrometer is developed employing a microchannel‐plate image intensifier, which acts as a high‐speed shutter (∼5 ns) by gating the applied voltage. Using such a spectrometer, we have achieved the measurement of temporal behavior of beam energy for various ion species of an intense pulsed ion beam extracted from a dual‐current‐feed magnetically insulated diode. The energy of protons is found to be in a good agreement with the diode voltage.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
42.79.Ls Scanners, image intensifiers, and image converters
42.79.Pw Imaging detectors and sensors
29.40.-n Radiation detectors
29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative

Fast, controlled stepping drive for D2 filament ejection

W. Amenda and R. S. Lang

Rev. Sci. Instrum. 56, 2283 (1985); http://dx.doi.org/10.1063/1.1138365 (4 pages) | Cited 2 times

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Centrifugal pellet injectors are required to refuel plasma machines. The pellet feed into the centrifuge should, if possible, be direct to keep the exit angle divergence small. The D2 filaments used are first stored in a cryostat and then rapidly transported to the intake region of the centrifuge. An intermittent drive for fast, controlled ejection of D2 filaments is described here. Mean filament speed of up to 0.6 m/s per step (1.2 mm) are achieved for the centrifugal pellet injector which refuels the ASDEX tokamak at Garching. The timing of the (81) step shifts can be synchronized with the rotor motion. The drive allows rates of up to 50 pellets per second. The drive method also seems to be suitable for direct feeding of other known centrifugal pellet injectors.
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28.41.Bm Fuel elements, preparation, reloading, and reprocessing
28.52.-s Fusion reactors
52.55.Fa Tokamaks, spherical tokamaks

Output voltage waveform improvement of the coaxial Marx‐type high‐voltage generator

Hidenori Matsuzawa and Tetsuya Akitsu

Rev. Sci. Instrum. 56, 2287 (1985); http://dx.doi.org/10.1063/1.1138366 (3 pages) | Cited 7 times

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A metal ring was installed to each of the main capacitor modules of the coaxial Marx‐type high‐voltage generator to increase the stray capacitance between the main capacitors and the cylinder of the outer conductor. Improvements in build‐up time of the output voltage were achieved and good agreements were obtained between the experimental and the simulated results.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
84.30.Jc Power electronics; power supply circuits
84.32.Tt Capacitors

Use of electron beam position modulation in Auger depth profile analysis

M. S. Leung and G. W. Stupian

Rev. Sci. Instrum. 56, 2290 (1985); http://dx.doi.org/10.1063/1.1138367 (5 pages)

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Auger analysis combined with ion etching in the scanning Auger microprobe (SAM) provides ‘‘three‐dimensional’’ composition information not readily obtainable from other analytical methods. As this technique is being applied to the analysis of microelectronic devices with increasingly smaller dimensions, two major limitations became evident: (1) features of interest in microelectronic circuits are often comparable in size to the beam diameter of commercial Auger microprobes and (2) the electron beam tends to drift about on the specimen surface because of mechanical instability and differential thermal expansion. We describe a technique that will reduce the error and uncertainty caused by beam instability. In our technique, the analyzing beam is scanned repetitively across the feature to be profiled and the Auger signal is synchronously detected at the scan frequency. This position modulation technique allows a tradeoff between depth resolution and sensitivity on the one hand and drift in spatial position of the analyzing electron beam. Position modulation is particularly suited to the analysis of microelectronic devices (e.g., microwave field effect transistors), where the dimensions of features of interest are comparable to the electron beam diameter.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
41.75.Fr Electron and positron beams
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Curved‐tube flowmeters

H. Houtman

Rev. Sci. Instrum. 56, 2295 (1985); http://dx.doi.org/10.1063/1.1138368 (4 pages) | Cited 6 times

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A new flowmeter design is presented which is suitable for accurately measuring flows ranging from ≂1 to ≂1000 cm3 s−1. It may be simply constructed from readily available parts and may be adapted to measure flow of any fluid for which a noncorrosive ball and transparent tube are available. Starting with standard Venturi meter theory, a formula is derived for the volume flowrate in terms of ball and tube dimensions, ball and fluid densities, and the angle at which the ball comes to rest in the tube. Actual examples of curved‐tube flowmeters are given for particular cases of nitrogen at 0 – 42.4 cm3 s−1 and water at 0–11.4 cm3 s−1, constructed using bearing balls in standard Eastman Polyflo tubing. Using the formula as a guide, extension to lower and higher flowrates is straightforward.
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47.60.-i Flow phenomena in quasi-one-dimensional systems

Directional sensitivity of unplated normal‐wire probes

M. Samet and S. Einav

Rev. Sci. Instrum. 56, 2299 (1985); http://dx.doi.org/10.1063/1.1138369 (7 pages) | Cited 2 times

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This paper describes an experimental study of the response to yaw of normal‐wire probes oriented at various roll angles with respect to the yaw plane. The results obtained show that unplated normal wires are most sensitive to yaw when the plane formed by the wire element and the prongs is aligned with the yaw plane. When the wire‐prongs plane is normal to the yaw plane, the sensitivity of these probes is reduced by 30 to 33%. When the wire‐prongs plane is inclined at 45° to the yaw plane, the probe response is almost insensitive to yaw within a large range of flow angles. The current experimental results are compared qualitatively with the ‘‘effective cooling velocity’’ model. It is shown that this model is too oversimplified to be correct; the tangential and the binormal cooling parameters are Re number and yaw dependent and, under certain flow conditions, the tangential cooling parameter k2 may even attain negative values. It is concluded, therefore, that much better signal‐interpretation expressions should be sought.
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07.10.-h Mechanical instruments and equipment
07.50.-e Electrical and electronic instruments and components
47.80.-v Instrumentation and measurement methods in fluid dynamics

Static method to measure vapor pressure in the temperature range below 1100 K

Jiro Nishimura, Takashi Numata, Hiromitsu Ogasawara, and Yoshio Sakanoue

Rev. Sci. Instrum. 56, 2306 (1985); http://dx.doi.org/10.1063/1.1138370 (4 pages)

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In this paper, a static method of measuring vapor pressure with an optically flat glass‐membrane pressure sensor in the temperature range below 1100 K is described. The furnace is designed so that the pressure can be measured contactlessly by the null method. A method of automatic pressure control using this sensor is described as well. The method is capable of controlling the pressure to the order of the sensitivity of the membrane.
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07.30.Dz Vacuum gauges
07.20.Hy Furnaces; heaters
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Computer‐compatible, self‐contained, precision ac resistance bridge suitable for thermometry

M. R. Corson

Rev. Sci. Instrum. 56, 2310 (1985); http://dx.doi.org/10.1063/1.1138371 (2 pages) | Cited 2 times

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A precision, self‐contained, four‐terminal ac resistance bridge with phase‐sensitive detection is described. The variable element in the bridge is a digital‐to‐analog converter, so that the setting of the bridge can be computer controlled. If computer control is not required, the bridge can be set using thumbwheel switches. The accuracy of the bridge is ±(0.03% of reading +0.01% of full scale). The dissipation in the unknown resistor is less than 1 μW for a full‐scale range of 99.99 Ω, and less than 1 nW for a full‐scale range of 99.99 kΩ. The low‐power dissipation, ac excitation, and four‐terminal configuration make the bridge especially suitable for resistance thermometry.
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07.20.Dt Thermometers
07.50.-e Electrical and electronic instruments and components
07.50.Ek Circuits and circuit components
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)

New microcalorimeter for the measurement of differential heats of adsorption of gases on high surface area solids

Matthew Orsquo;Neil, Rex Lovrien, and Jonathan Phillips

Rev. Sci. Instrum. 56, 2312 (1985); http://dx.doi.org/10.1063/1.1138372 (7 pages) | Cited 10 times

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A new calorimeter of the heat‐flow type designed to measure the differential heats of adsorption of gases on high surface area solids (e.g., catalysts) is described. Heat flow is measured using conventional thermopiles; the signals from which are amplified, digitized, and then sent to a laboratory computer for ease of data handling and analysis. The instrument allows conventional isotherm and heat data to be collected concomitantly. Other useful information obtained includes qualitative data regarding the rate at which processes take place, the total amount of gas chemisorbed, and the integrated value of the heat of adsorption. The instrument is capable of operating at temperatures from 273 to 373 K. One major advance over previous designs is that the dosing gas is allowed to thermally equilibrate before entering the sample chamber. The results of a simple study of the differential heats of adsorption of oxygen on a high surface area carbon material are presented. This study demonstrates the reliability and utility of the instrument.
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07.20.Fw Calorimeters
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
05.70.-a Thermodynamics
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