Spectrometer Unit Research Articles

Operating Room Fires: Optimizing Safety

This prospective study was undertaken to determine the safest means of supplemental oxygen delivery for patients undergoing facial cosmetic surgery under conscious sedation. Two common methods of oxygen delivery were used in 20 patients: (1) a nasal cannula and (2) a red rubber nasopharyngeal tube through which the cut ends of the nasal cannula were passed into the posterior pharynx. The project was carried out in two parts. In part one, each subject was placed supine and oxygen supplementation at 3 liters/minute was applied through the nasal cannula. The oxygen concentration at 24 different set locations around the patient's face was analyzed using the random access mass spectrometer unit, starting at the right and left alar rim and then at 2-cm intervals laterally, superiorly, and inferiorly. The procedure in part one was repeated with oxygen being delivered by passing the cut cannula end through a red rubber nasopharyngeal tube into the posterior pharynx. Statistical analysis has showed that in all sites at or above the nasal area, the difference between the nasal cannula and red rubber nasopharyngeal tube is significantly greater than 0, indicating that higher concentrations are observed with the nasal cannula than with the red rubber nasopharyngeal tube (p = 0.004). The authors' study demonstrates a significant reduction in oxygen concentration, to levels consistent with ambient air, even at points extremely close to the oxygen source, when the nasopharyngeal tube system was used.

In Situ Mass Spectrometry for Chemical Identification in SiC Epitaxial Deposition

A quadrupole mass spectrometer unit was utilized to accurately detect the chemical species present inside a SiC CVD reactor growth chamber before, during, and after epitaxial deposition. The in-situ mass spectrometer has been able to confirm the presence of silane (SiH4) and propane (C3H8) decomposition products (eg. Si and CH4) that were predicted from chemical modelling, and give insight into specific reaction kinetics. Additionally, the mass spectrometer has positively detected trace amounts of oxygen, which has helped to identify process weaknesses and possible sources of vacuum leaks.

Microanalysis station at the Kurchatov synchrotron radiation source

The REFRA station developed, fabricated, and put into operation at the Kurchatov Synchrotron Radiation Center is described. The station is placed on beamline 5.6 of the big storage ring. The station consists of a vertical beam position monitor, an operating shutter, vertical and horizontal slits for the white beam, a monochromator, an alignment stage, an intensity monitor, an EXAFS spectrometer unit, a diffractometer unit, detectors, and a data control and acquisition system. The station operating energy range is 5–30 keV. The station is fully-automated and has been operating with the SR beam since spring 2005. The station units can be reproducibly mounted on the SR beam to provide various research configurations.

Monte carlo simulation and optimization of three-axis neutron spectrometer for the PIK reactor

Mathematical modeling of estimated parameters for optimization of the three-axis neutron spectrometer developed at the Ioffe Physicotechnical Institute for the PIK reactor have been performed. The expected intensities and spatial distributions of neutron fluxes at the points of location of spectrometer units are reported. The spectrometer resolution function is calculated.

PROCESSAMENTO E INTERPRETAÇÃO DE DADOS GAMAESPECTROMÉTRICOS AÉREOS DO PROJETO ITABIRA-FERROS, MG: UMA FERRAMENTA NO AUXÍLIO AO MAPEAMENTO GEOLÓGICO

The area covered by the Itabira-Ferros Project is located in the Iron Quadrangle, State ofMinas Gerais, and is known for its emerald occurrences. The present study applies geophysical characteristics, using airborne gamma-ray spectrometric data and their integration with geology, to determine probable zones of emerald mineralization. The total count gamma-ray image allows the definition of the spectrometric framework ofthe area. Analyses ofthe elements K, Th, and U distribution were conducted together with RGB and CMY ternary images, leading to the identification of spectrometric geological units and structures. A total of 20 gamma-ray spectrometric units is identified for the region. Most ofthem are correlated to mapped units geological and others with no apparent correlation. A map with interpreted garnma-ray spectrometric structures shows that mineralizations are located in areas of extreme faulting, specially at the edges ofthe sigmoidal feature in unitill, reflecting ductile displacement. Known mineralizations form a belt, trend like structure in NW-SE direction, between two faults in the sarne direction and the cities of Joao Monlevade and Dores de Guanhaes. Emerald mineralizations are located in the eastern portion ofthe sigmoid, others mineralizations are directly related to the sigmoid at its central portion and to other NW features cutting the area.

Observations of sheared radial electric-field effects on turbulence suppression

Significant effects of sheared transverse electric fields in plasmas on both turbulent fluctuations and drift waves are experimentally demonstrated with improvement in plasma confinement for the first time in the tandem mirror GAMMA 10. These electric-shear effects are performed on the basis of a factor of 2 advance in ion-confining potential formation. For analyzing these phenomena in detail, we develop a novel electrostatic ion-energy spectrometer array consisting of five spectrometer units. The spectrometer arrays have the characteristic advantage of having no disturbances from potential-producing electron-cyclotron wave heated energetic electrons. Totally four array arms having each a 90° separation located on each GAMMA 10 end wall make it possible to observe two-dimensionally resolved radial-distribution profiles of plug and/or central potentials as well as radially produced shear of electric fields along with the earlier-described fluctuation signals simultaneously.

Observations of differences in the spatial-profile symmetry-of ion-confining potentials in the cases with and without the central-cell density increase during an ion-plugging period

Temporal evolution of radial profiles of end-loss-ion currents, ion temperatures, and ion-confining potentials φc is investigated in the GAMMA 10 tandem mirror by the use of our newly designed electrostatic ion-energy-spectrometer arrays. In tandem-mirror experiments, plasma-confining potentials produced by electron-cyclotron heatings (ECH’s) play one of the most critical roles in the improvement of simple-mirror plasma confinement. For the observations of these confining potentials, the development of ion-diagnostics equipment providing clear energy spectra without disturbances from ECH produced energetic electrons is of essential importance, since conventional multigrided Faraday cup signals are seriously influenced by such incident electrons. Each spectrometer unit in our developed array has a specific structure with obliquely placed multiple grids with respect to the direction of the ambient lines of magnetic force for plasma confinement. The relation between the spatial profiles of end-loss-ion fluxes IELA and those of φc is investigated by the use of these newly designed ion-energy-spectrometer arrays installed in both end regions of GAMMA 10. The first remarkable finding of axisymmetric profiles of φc having a good correlation with axisymmetric plugging distributions in IELA along with the central-cell density nc increase is made; while, the contrary result without nc increase even during a plugging period is found with asymmetric profiles of φc with asymmetric plugging profiles in IELA. In the article, detailed data comparison between the two is reported by the use of each single-plasma discharge with the developed ion-spectrometer arrays.

On-Line Sorting of Wood Treated with Chromated Copper Arsenate Using Laser-Induced Breakdown Spectroscopy

This paper details the design, implementation, and field evaluation of an online detector system using laser-induced breakdown spectroscopy (LIBS) for the analysis of copper chromated arsenate (CCA) treated wood products. The LIBS-based instrument functioned by creating the laser-induced plasma directly on the sample surface while wood was translated under the detector system, and was successful in discriminating between CCA treated wood and untreated wood products based on the atomic emission signal of chromium. The system was optimized for plasma emission collection both in and out of the laser focal plane and temporally optimized for chromium analysis using a compact, non-intensified charge-coupled device (CCD)/spectrometer unit. Using either single laser pulse spectra or 5-shot and 10-shot spectral averages, the accuracy of LIBS-based analysis ranged from 92 to 100% for identifying both CCA treated and untreated wood samples from the waste stream at a construction and demolition debris recycling center. Additional implementation issues are discussed in the context of LIBS-based on-line sorting of construction and demolition wood debris.

Analysis of bulk and powdered samples using a LAMAS-10M laser ionization time-of-flight mass spectrometer

The problem of the modernization of a LAMAS-10M laser desorption/ionization time-of-flight mass spectrometer was considered, and the methodological fundamentals of the quantitative analysis of bulk and powdered samples by laser desorption/ionization time-of-flight mass spectrometry were discussed. Basic modifications of certain spectrometer units were described, and the reproducibility and accuracy that can be attained using these modifications were estimated. The possibility of the quantitative analysis of bulk samples was demonstrated. These studies were performed using bulk and powdered standard reference materials. In determining precious metals in geological samples, the detection limit for powdered samples was (20–50) × 10–9. The relative standard deviation for the repeatability of the results (RSD) of the bronze standard reference sample “bronza 663” was in the limits RSD = 0.06–0.4% for the major component and 0.5–4.5% for the elements present in percent concentrations. It was shown that the majority of analytes can be determined at a semiquantitative level without using standard reference materials. The key problems of laser desorption/ionization time-of-flight mass spectrometry were considered and methods were proposed to solve these problems. Ways to further improvement of the characteristics of the mass spectrometer were demonstrated.

Segmentoid Electrostatic Analyzers for Detection of Low-Energy Charged Particles

A new type of electrostatic analyzer for the detection of low-energy charged particles (denoted as a segmentoid analyzer) was developed. The field strength between the plates of the analyzer was determined. A small-size spectrometric unit was developed on the basis of the segmentoid analyzer and the ВЭУ-7 secondary-emission multiplier (particle detector). The main characteristics (energogeometric coefficient and angular and energy transmission curves) of the spectrometric unit were considered. The calculated value of the energogeometric coefficient agrees well with the experimental value obtained during calibration.

Simultaneous observations of temporally and spatially resolved two-dimensional profiles of ion-confining potentials and ion fluxes using novel ion-energy spectrometer arrays

Newly designed spectrometer arrays for ion-energy-spectrum observations are proposed and constructed in both end regions of the GAMMA 10 tandem mirror so as to obtain two dimensionally resolved radial profiles of end-loss-ion fluxes IELA, ion temperatures, and ion-confining potentials φc by the use of a single plasma discharge alone. Each spectrometer unit in the array has a specific structure with obliquely placed multiple grids with respect to the direction of the ambient plasma-confining magnetic fields. This structure is proposed to obtain precise ion-energy spectra without the disturbance of simultaneously incident energetic electrons into the array, since widely distributed “multigridded Faraday cup” signals have significant electron disturbances on ion spectra even if over a few tens of kV are applied to the electron-repeller grid. In tandem-mirror experiments, plasma-confining potentials produced by electron cyclotron heatings play one of the most critical roles in the improvement of simple-mirror confinement. Thus, diagnostics of these confining potentials using clear ion spectra are of essential importance. From these motivations, the spatial distribution details and relations of φc and IELA are investigated by the use of the novel ion spectrometers. Axisymmetric profiles of φc are found to have a good correlation with axisymmetric plugging distributions in IELA. These are consistently interpreted in terms of the Pastukhov theory of the relation of φc with IELA. Information on such specific spectrometer arrays would contribute to researchers in a wide variety of plasma devices, who employ analyzers for flux, temperature, and potential diagnostics under energetic plasma circumstances.

Detection of Hydrocarbons in Water by MIR Evanescent-Wave Spectroscopy with Flattened Silver Halide Fibers

IR transmitting AgCl xBr1- x, fibers were used as internal reflection elements for the spectroscopic detection of hydrocarbons that are dissolved in water in an attenuated total reflection (ATR) type of setup. The fibers were partly flattened by pressing and then coated with an analyte-enriching organic polymer in order to increase the sensor sensitivity. A portable tunable diode laser spectrometer served as a spectrometric unit. The dependence of the sensitivity on coupling conditions was investigated and lead to an optimized coupling. It is shown that the sensitivity of the flattened waveguide with a thickness of 170 μm can be enhanced by a factor of 5 compared to a fiber with 900 μm diameter. Aqueous toluene solutions with concentrations in the parts-per-million range were used to characterize the sensor system that showed a linear response with regard to analyte concentration. The noise equivalent concentration (NEC) was on the order of 1 ppm.

LED-based NIR spectrometer module for hand-held and process analyser applications

This paper discusses an electronically scanned, small size 32-wavelength NIR spectrometer unit developed for use as a building block in hand-held composition meters as well as in spectroscopic sensors for process automation. The design relies on a linear LED array light source and a fixed grating monochromator. The benefits of the LED spectrometer unit are a highly accurate wavelength scale, with fixed precalibration for subnanometer tolerances and compatibility with a wide operating temperature range, thanks to internal temperature stabilisation. A series of LED spectrometer modules was manufactured for short wave near infrared (SW-NIR) specifications, covering the range from 832 to 1048 nm and a testing program was arranged to characterise typical performance and the spread of the key optical parameters. Potential applications for this SW-NIR wavelength scale can be seen in food, agricultural and petrochemical analysis. The design can also be modified for other wavelengths, for which LEDs are currently available, i.e. from 400 nm to beyond 2 μm, which will further widen the scope of possible applications in the field of NIR spectroscopy and colour analysis.

A New Inlet System for Differential Electrochemical Mass Spectroscopy Applied to the Photocorrosion of p‐InP(111) Single Crystals

A new inlet system for the application of the differential electrochemical mass spectroscopy to massive electrodes is presented. The main advantage of our electrochemical cell is the free access of the massive electrode surface, which allows a homogeneous illumination of the electrode/electrolyte interface as well as measurements in the presence of strong gas evolution (high current densities). Because the cell is directly connected to the high‐vacuum chamber of the mass spectrometer unit, a good sensitivity is achieved with a relatively simple experimental setup. As an example for a photoelectrochemical system, p‐InP(111) single crystals were investigated in the dark and under illumination during cathodic scans in . Simultaneous to the hydrogen evolution, a photocorrosion can be observed via the mass signal of phosphine . Energy dispersed analysis of X‐ray fluorescence and scanning electron microscopy measurements reveal the formation of metallic indium sites at the electrode surface due to the corrosion process. It is shown that the electrodeposition of platinum onto the surface of a bare p‐InP(111) electrode leads to a catalytically enhanced hydrogen evolution whereas the corrosion process is drastically suppressed.

Compact grating spectrometer for inverse photoemission spectroscopy

We report on a normal incidence grating spectrometer for angle-resolved inverse photoemission spectroscopy covering a photon energy range from 10 to 40 eV. Following diffraction from a spherical grating with 201.4 mm radius and 3600 lines/mm the photons are recorded by a position sensitive detector. The compact mounting of the grating and detector on a single 150 mm CF flange is established by displacing detector and sample from the Rowland circle. The performance of the spectrometer concerning energy calibration, spectral efficiency, optical resolution, and count rates was experimentally investigated and found to match the design goals well. Operated together with a low energy electron gun using a low temperature BaO cathode a typical total energy resolution of 360 meV at hν=15 eV is obtained in inverse photoemission spectroscopy. It is shown that due to its compactness the spectrometer unit can be effectively combined with other components for surface analysis.

Rapid Measurement of the Gaseous41Ar Released from a Nuclear Reactor Using a Portable Spectrometer

method to monitor in situ the dose rate from the gaseous radionuclide 41 Ar is developed using a portable gamma-ray spectrometer. A high-purity germanium detector with a sensitivity of 0.358 nSv/h per count per minute is used to calibrate 1294-keV gamma rays emitted from radioactive 41 Ar. Field measurements are conducted both inside and outside of the containment of a nuclear reactor during full-power operation, and iso-dose rate contour curves are mapped. The in situ measurement can be readily performed at various locations near a nuclear reactor with a 14-kg portable spectrometric unit. The detection limit for a 1-h counting period is as low as 0.35 nSv/h for the gaseous 41 Ar. One can use the method and field measurements developed in this research to quantitatively determine the gaseous fission products of krypton and xenon dispersed from a nuclear power plant.

Coherent variations of monthly mean total ozone and lower stratospheric temperature

Space‐time patterns of correlation between total ozone and lower stratospheric temperature are documented, based on 14 years (1979–1992) of global monthly mean observations. Data are obtained from the total ozone mapping spectrometer (TOMS) and microwave sounding unit (MSU) channel 4, the latter being a weighted mean temperature of the 150‐ to 50‐mbar layer. These data are analyzed (separately) for linear trend, solar cycle, quasi‐biennial oscillation (QBO), and El Niño‐Southern Oscillation (ENSO) variations via linear regression: significant signals are identified for each term, and the corresponding structures in ozone and temperature are found to be highly coherent. The temperature trends derived here show significant cooling of the lower stratosphere over Northern Hemisphere (NH) midlatitudes in winter‐spring and over Antartica in Southern Hemisphere (SH) spring; the overall space‐time patterns are similar to those determined for ozone trends. Interestingly, temperatures do not decrease over SH midlatitudes during midwinter, in spite of large ozone losses. These data furthermore show globally coherent ozone and temperature perturbations associated with both QBO and ENSO variations; a new result here shows large total ozone anomalies in middle‐to‐high latitudes of both hemispheres associated with ENSO events. Residuals from the ozone and temperature time series (defined as the deseasonalized total minus the regression fits) show strong positive correlation in middle‐to‐high latitudes but weak correlations in the tropics. Time periods following the volcanic eruptions of El Chichon and Pinatubo are clearly identified from the coupled signatures of decreased ozone and increased temperature, opposite to the positive ozone‐temperature correlations observed at other times. The ratios of ozone to temperature anomalies derived here show quantitative signatures indicating that either radiative (trend, solar, and QBO) or dynamical (ENSO and residuals) processes are responsible for the strong ozone‐temperature correlations.

The accuracy, precision and stability of a (scanning) transmission electron microscope with a parallel electron-energy-loss spectrometer assessed by measurements of the plasmon energy of aluminium

Abstract The accuracy, precision and stability of a parallel electron-energy-loss spectrometer on a (scanning) transmission electron microscope has been assessed by the measurement of the plasmon peak energy of Al at and below room temperature. An absolute instrumental accuracy of ± 0.04eV (3[sgrave] confidence limits) was obtained with a relative accuracy of ± 0.015 eV. Hardware and software had to be developed to extend the energy resolution beyond the inherent resolution of the parallel electron-energy-loss spectrometer unit used.

An updated program-controlled analog processor, model AP-006, for semiconductor detector spectrometers

An analog processor, model AP-006, is reported. The processor is a development of a series of spectrometric units based on a sharper of the type “DL dif+TVS+gated ideal integrator”. Structural and circuit features are described. The results of testing the processor in a setup with a Si(Li) detecting unit over an input count-rate range up to 5 ×10 5 cps are presented. Processor applications are illustrated.

The precision calcium photometer: A New Instrument for Astroseismology

The Precision CAlcium Photometer (PCAP) has been built with characteristics optimized for amplitude astroseismology. The instrument consists of two units: an on-telescope optical system that forms and stabilizes a stellar image onto a 200 micron optical fiber; and a spectrometer unit that accepts the light from the fiber and integrates the Calcium II H and K lines (3968.5 Å and 3933.7 Å), along with adjacent continuum regions, in a photon-counting mode. Some key system characteristics include active image stabilization, a 12-meter optical fiber with ~70% transmission at 3950 Å, and a thermally and mechanically stable spectrometer. A description of the instrument and of laboratory and on-telescope test runs are discussed below.