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In this work, we studied the effect of swirl flows in the turbulent and non-turbulent flame on soot formation in a methane/air fuel-rich combustion at atmospheric pressure. Combustion air and methane were supplied to an experimental combustor through a coaxial nozzle to form diffusion flame. The equivalence ratio was kept at 1.9. In general, the flames are luminous during a fuel-rich combustion. Based on Plank’s law and other researches, the intensity level of emission from soot particles and soot concentration are increased with increase of temperature. However, the flame resulting in our experiment was not as described above. This result is discussed in conjunction with the experimentally observed distributions of temperature, continuum emission of radiation from soot particles, chemical species, and soot volume fraction. The results indicated that the temperature in the turbulent flame was higher than in the non-turbulent. In spite of the high flame temperature, soot continuum emissions and soot volume fraction in the turbulent flame were decreased. In addition, it was notice that H2 and CO concentrations in the turbulent flame were twice as high as that in the non-turbulent flow. Therefore soot formation was related to H2 and CO.

In order to investigate the characteristics of the surface of substrates without destroying and touching them, two-dimensional (2D) surface brightness distributions have been measured with a CCD camera equipped with optical filter (700-800 nm). The images measured with each wavelength gave 2D temperature distributions by two-color thermometry. In addition 2D emissivity distributions were also derived from the derived 2D temperature distribution and the measured images. We demonstrate the convenience and usefulness of this method for heated materials with different surface roughness or with and without coasting of high emissivity material. Subject headings: 2D-temperature distribution, two color method, high temperature, emissivity

Temperature control in the sintering process is important to secure the quality of ceramics. We have usually controlled the sintering process indirectly by making use of the temperature of the inside of a furnace. It has been a general understanding that infrared radiometric thermograph is not suitable for measuring directly the temperature of the targets such as ceramics placed in the furnace because of emissivity dependence of the targets and because of the effect of reflection from the furnace wall. The same can be said to 2-colored thermometers because of them, too, it has been impossible to eliminate the effect of reflection for correct temperature measurement. Recently we, however, contrive two new methods for direct measurement of the surface temperature of ceramics using a 3-colored thermograph. One is to measure the indefinite emissivity of the inside of a furnace and the effect of reflection from the furnace wall. The other is to eliminate such indefinite emissivity and effect of reflection. We will report the new methods of 3-colored thermograph and the result of inspecting the said methods.

Nitrous oxide (N2O) is a relatively stable compound, present at ∼310 nL/L in the atmosphere. It is produced predominantly by microbial reduction of nitrate (NO3−). This process, called denitrification, is the conversion of nitrate to gaseous nitrogen compounds, resulting in a product of nitrogen (N2) or nitrous oxide under most conditions. Many kinds of denitrifying bacteria have been isolated from the human oral cavity, upper respiratory tract, and alimentary tract (e.g.) (1)(2)(3)(4), including pathogens of Pseudomonas , Neisseria , and Campylobacter. Taking these studies into consideration, it is proper to assume that the concentrations of N2O in exhaled air exceed those in the atmosphere, although no studies have been published related to N2O in exhaled air. The purpose of this study is to establish an analytical method for detection of N2O in exhaled air by using gas chromatography (GC) and infrared-photoacoustic spectrometry …

Daily chromatographic investigation of the nitrogen(I) oxide content of the atmosphere at Ryori in Japan has shown a steep increase in concentration during the 1990s. The incremental increase was 5–9 ppbv, compared with the world-wide estimate for 1975–1985 of 1 ppbv.

To study characteristics of heated material surface over 600 K, non-contact measurements of two-dimensional (2D) distributions of temperature and emissivity are very useful for process monitoring in engineerings, because of remote sensing in a short time. The 2D temperature distributions enable us to monitor the surface temperature quantitatively with high spatial resolution. The 2D emissivity distributions give us a capability to judge thermal degradations or defects of the surface. The 2D distributions of temperature and emissivity determined by two-color method using a CCD camera and two optical filters have been already reported by many authors. In this study, a four-color method is proposed to improve accuracy and precision of the temperature and emissivity. Four optical filters with narrow bandpass of 10 nm were used for our measurements, because the thermometry using narrow band is advantageous over that using wide one in terms of accuracy of temperature determination. Distributions of temperature and emissivity were also determined by two-color method for comparison. The results obtained by the four-color method have higher accuracy and precision than two-color method and we can recognize that several conditions of the material surface are clearly illustrated by the resultant 2D emissivity distribution.

A discharge lamp was constructed as an excitation source for the determination of trace elements in small samples by atomic emission spectrometry. A graphite cup, in which an aliquot (10 mg) of sample solution or powder was loaded, was located in a stainless-steel cylinder. An r.f. discharge was formed between the graphite cup and the grounded cylinder under a reduced pressure of argon. Concurrently with the formation of the plasma, the graphite cup was heated to about 1900 °C owing to the r.f. power dissipation. As a result, the sample was thermally vaporized and/or atomized, and subsequently excited to emit radiation in the discharge plasma surrounding the graphite cup. Basic characteristics were studied in conjunction with the analytical performance. The matrix effect of sodium was tested and found to be negligible in the determination of copper in the presence of up to a 1000-fold excess of sodium. A linear dynamic range of the calibration graph was obtained over about four orders of magnitude of analyte mass. The discharge lamp was applied to the direct determination of copper, zinc and chlorine in National Institute of Standards and Technology Standard Reference Materials of biological samples.

The effect of an easily ionizable element (EIE), potassium, was studied for the excitation systems of iron atoms and ions in an inductively coupled plasma supported by a Meddings–Anderson–Kaiser torch. The spatial and power dependences of the EIE effect are related to the change in the deviation from the Boltzmann distribution, which is expressed in terms of the curvature of the Boltzmann plot, the tangential temperature and the change in the relative number densities of iron atoms and ions.

The deviation from the Boltzmann distribution was studied for the excitation of iron atoms and ions in an inductively coupled plasma supported by a Meddings–Anderson–Kaiser torch. Its spatial and power dependences are discussed in conjunction with such properties as curvature of the Boltzmann plot, tangential temperature and relative number densities of the iron atoms and ions.

Spectral features of atomic magneto-optical rotation spectroscopy (AMORS) or the atomic Faraday effect of various elements are described. As a stable atomizer, an air-hydrogen flame is located between the pole pieces of the electromagnet. The dependence of the transmitted intensity on the magnetic field strength was recorded on an X-Y recorder by scanning the magnetic field. For most of the analytical lines of elements, the maximum energy was transmitted through the optical system in the Faraday configuration at magnetic field strengths of up to a few kilogauss. The theoretically calculated Zeeman splitting patterns are successfully related to the experimental results.

The atomic Faraday effect has been applied to the trace determination of lead in NBS Orchard Leaves, human blood, and volcanic ashes. Suspensions of powder samples and diluted whole blood are directly pipetted into a graphite tube atomizer. Spectroscopic and practical features are discussed of the atomic Faraday effect of lead. The inherent feature of insensitivity to background scattering makes the present technique suitable for practical analysis. The problem associated with loss of transmitted optical energy caused by non-atomic species was overcome by a correction method. Consequently, the present technique enabled us to perform rapid analyses, gave a detection limit of 5 × 10−11 g and fair accuracy, at least satisfactory for practical analysis. Some problems arise from residue build-up in the atomizer.

Synopsis A separative column atomizer (SCA) heated with a silicon carbide (SiC) heating element was constructed for the direct determination of the trace amounts of Cd. Its capability of chromatographic separation of atomic vapor from non-atomic species was examined on the direct atomization of biological samples. The SCA was heated up to 1420°C. The species formed by decomposition under a flow of argon were followed by reaction and/or separation in the SCA packed with graphite granules, and subsequently the atomic absorption of Cd was measured at the column outlet. The non-atomic absorption gave no background absorption problems because of the gas chromatographic separation between non-atomic and atomic vapors through the SCA.

In order to increase source intensity, hollow cathode lamps were operated in a pulse mode and combined with instrumentation for Faraday or atomic magneto-optical rotation spectroscopy. The analytical and spectral features of this method were studied for the trace determination of elements Sb, Bi, Ag and Cu. Novel line crossings between the σ ± -components in the analytical line Bi I 306.772 nm were found from the dependence of the transmitted intensity on the magnetic field strength. This is related to the theoretically calculated Zeeman splitting pattern. The enhancement in the source radiance by the pulse mode gave an increase in the detection power by a factor of ten.

A system has been constructed, which couples a new type of thermal vaporizer to a capacitively coupled microwave plasma (CMP). It is used to determine trace levels of Hg in water. A sample solution of 2-7ml is jetted onto a fused silica wool heated to 630-945°C and thermally vaporized. A large volume of the resulting steam is removed by a highly efficient double coaxial wall condenser. The desolvated mercury solute enters the CMP; 253.65 nm emission is monitored. Basic system characteristics studied include vaporizer temperature, gas flow rates, detection limits, dynamic range and matrix effects. Linear calibration curves are obtained for concentrations ranging from 1 to 1000 μg/l.

A novel atomizer effective for direct analysis was developed using a new type separative column atomizer (SCA) module. The SCA module incorporated an atomization part, a separation column and/or reaction column part and observation windows for atomic spectroscopic measurement. This module was applied to the direct analysis of trace amounts of mercury and cadmium in practical samples. No background absorption was observed on the thermal decomposition of synthesized samples in a starch matrix and human hair at the wavelengths of the analytical lines of Hg and Cd. The effectiveness of the technique for the determination of elemental compositions is evaluated.

Application a des dosages dans des feuilles, du foie d'animal, du jus d'orange et des cendres de volcan

The basic characteristics of a separative column atomizer (SCA) were studied in conjunction with the retention of atomic vapors of Hg, Cd and Pb. The column atomizer consists of an alumina tube heated at 800-1400°C, which is packed with graphite granules coated with Au or Pt, or mixed with Sn powder. Different retention characteristics and peak broadening were observed for different packings. The retention of atomic vapor through the SCA might be useful for the separation of coexisting elements and the removal of their interference.

Using a magnetized hollow cathode lamp as a Zeeman-shifted light source, the effects of the source line profile on the intensity of rotatory radiation and the calibration curve were studied for AMORS (atomic magneto-optical rotation spectroscopy). With the alteration of the source line profile, an increase in the intensity of rotatory radiation by about max. 40% was found. The rollover of the calibration curve could be avoided by selecting the strengths of the magnetic fields applied to the atomizer and the hollow cathode lamp.

An improved separative column atomizer (SCA) usable at higher temperatures up to 1350°C has been constructed. Emphasis in this article is on the GC characteristics of an improved separative column atomizer (SCA) module to reduce the interferences caused by background absorption that is often unavoidable in direct analysis of practical samples. By direct AAS analysis, mercury in some organic samples has been successfully determined without background absorption due to non-atomic species resulting from the sample matrices. In the direct atomization of samples in EDTA matrix, however, complete elimination of the background absorption was not possible. Nevertheless, GC separation found in the improved SCA was effective in the measurement of the AA peak free from molecular absorption. Evidences of the GC separation were also given by the analysis of effluent gases.

Magnetic field modulation is used in conjunction with an offset angle on the polarizers to improve the analytical capabilities of atomic magneto-optical rotation spectroscopy (AMORS). The offset angle method linearizes the quadratic response to density of atoms and lowers the detection limit. However, d.c. photocurrents induced by leakage of source light due to the offset angle can produce varying baselines because of background absorption or light source fluctuations. The application of a modulated magnetic field to the atomic vapor and frequency selective detection enables the elimination of the d.c. offset signal.

The Fraunhofer diffraction of laser radiation was applied to the correction of physical interference in a nebulizer used for atomic absorption spectrometry. A chamber with windows was mounted between the nebulizer system and the burner head. A He-Ne laser beam passing through the chamber was diffracted by droplets and constructed an image. The diffraction image received by a linear image sensor of 1024 elements was processed by a microcomputer to obtain the size distribution and the total volume of the droplets. The correction was made by dividing the absorbance by the total volume.

A new type of rapid scanning spectrometer was constructed for use in analytical atomic spectroscopy. The sine-bar and its driving system are disabled and the grating is driven directly by a synchronous motor. The wavelength synchronization is made by counting the photopulses generated by the combination of a small tungsten lamp, a phototransistor and a slotted aluminium disc which is attached to the shaft of the rotating grating. In an on-line and real-time mode, a variety of measurements can be achieved by a dedicated microcomputer. The basic analytical performance was evaluated and some applications are demonstrated.

Emission spectroscopy is applied for characterization of reactions occurring in air—acetylene flames normally used for atomic absorption spectrometry. Inter-element effects on the emissions of chromium and iron are discussed. Two atomic emission lines with different upper energies and a molecular emission line of the diatomic oxide MO are compared for determination of the excitation temperature and the degree of atomization in fuel-rich and lean flames. The reductive power of the fuel-rich flame is essential for atomization of chromium salts. Inter-element effects by iron can be attributed to the formation of refractory oxides, and to mutual catalytic oxidation.

A microwave-boosted do discharge lamp with a hot graphite cathode was constructed for trace analysis of elements by atomic emission spectrometry. Its basic characteristics and effects of microwave were examined. The results indicated that several analytical improvements were obtained by microwave-boosting: the signal-to-noise ratio was enhanced, emission peak splitting was minimized and the matrix effect caused by coexisting sodium was suppressed.

The degree of atomization, β, is measured for an electrothermal atomizer by comparing the emission lines of copper atoms and CuCl molecules. Hydrogen increases the β value. The determined β value of CuCl is used as a standard for the determination of β values of other elements (nickel, chromium, tin and lead).

A non-dispersive AMOR (atomic magneto-optical rotation) analyzer was tentatively con structed for multielement analysis and its analytical performance was examined for deter minations of Mg and Zn. The hollow cathode lamps of Mg and Zn were modulated at different frequencies. The source radiations from the lamps were merged by a grid mirror. The rotatory radiation emerging from the optical system in the Faraday configuration was received by a solar-blind photomultiplier tube. The signals of Mg and Zn were separated by the fast Fourier transformation (FFT) processing.

A four-line method is described for correction of inter-element effects caused by variations of excitation temperatures and the degree of ionization in a plasma. Four lines with different upper-level energies in the atomic-ionic system are compared. The total number of atoms and ions is used as the response instead of the spectral intensity. Plasma torch symmetry is one of the most important factors for successful corrections. The correction method is demonstrated for the determination of manganese in a capacitively coupled plasma torch, where strontium interferes strongly.

Graphite electrodes heated by d.c- power alone, or a combination of d.c- and r.f. power, are investigated for generating atomic emission from cadmium with specially designed discharge lamps. Best results are achieved if the plasma produced by both power sources can be concentrated within a cylindrical electrode.