Rapid-scanning Spectrometer Research Articles

Atomic Absorption Flame Temperature Distribution Measured by Fiber Optics

Abstract Atomic absorption flame temperature distributions have been investigated. The two-line method based on the fiber optics coupling light into the rapid-scanning spectrometer to measure temperature has been developed. Its feature is that a simpler apparatus used can obtain temperature distributions over the entire section of the flame in high resolution. The result shows some characteristics of premixed air-acetylene flame used for analytical spectrometry.

Flame Temperature Remote Determination from Spectrometry Based on Fiber Optics

Abstract The mode using the two-line method based on fiber optics to measure flame temperature by a rapid-scanning spectrometer is presented. The measurement system developed by us useful for remote measurement or to carry an optical signal in and out of environments like too low or too high temperatures, high magnetic field etc. is described in detail. The technique is discussed and compared with other methods in flame spectroscopy. Our results show that the advantages of this method are very sensitive, flexible, rapid, convenient and accurate. The further applications such as using the method in automation design or process automation are also discussed.

The Application of Linear PA/FT-IR to Polymer-Related Problems

A simplified method has been developed which allows the computation of linear photoacoustic FT-IR spectra using only one sample and one reference interferogram from a commercial, rapid-scan spectrometer. The application of linear computation to photoacoustic infrared data can produce spectra similar to transmission spectra through the reduction, if not elimination, of the saturation artifacts typical of amplitude computation, the usual mode of producing a PA/FT-IR spectrum or a transmission mode spectrum. Comparison of the resulting linear spectra with amplitude spectra has been used to demonstrate the existence of surface layers on top of substrates. Qualitative identification of the surface layer is easier in this mode than in the case where amplitude spectra are obtainted at the extremes of instrument mirror velocity. Additionally, information concerning a polymer matrix in the presence of up to 25 wt % carbon black is contained in linear photoacoustic spectra. Linear photoacoustic FT-IR spectra of carbon-filled samples are easier to interpret in comparison to spectra obtained by amplitude methods.

Two-step regression procedure for the optical characterization of thin films

A diode array rapid scan spectrometer is used for measuring the intensity of polychromatic light in the 300-420-nm range reflected from a diamondlike carbon film as a function of wavelength. With a fixed grating setting, the wavelength range of 120 nm can be covered in 23 ms. From the reflected intensity, a new two-step regression procedure is utilized to determine refractive index, bandgap, slope of the absorption edge, and film thickness. The calculated parameters are independent of the starting set and the sequence of parameter estimation. The accuracy of the regression procedure is verified by comparison to the envelope method. It is shown using simulated data that, for strongly absorbing films, the new regression procedure is more accurate than the envelope method. The new regression method can handle very noisy reflectance spectra also.

Rapid-scanning spectrometer based on fiberoptics applied to flames

A rapid-scanning optical spectrometer based on fiberoptic probes, used to measure radical emission in low-pressure premixed laminar flames, is presented. Emission spectra and intensity profiles as a function of height above the burner have been recorded for OH, CH, and C2 in an ethylene/oxygen/nitrogen flame (14% C2 H4 , 64% O2 , 22% N2 ), stabilized at 5 Torr on a sintered stainless-steel burner. The emitted light was guided from the flame reactor to the spectrometer by fused silica optical fibers. Rapid scanning (100 scans/s) eliminates the effects of turbulence and temporal signal fluctuations, as 104 –105 scans over a preset spectral window are collected and signal averaged within a few minutes. The technique is discussed and compared to classical methods in flame spectroscopy.

Line selection expert system for control of scanning inductively coupled plasma atomic emission spectrometers

An expert system for control of a rapid scanning spectrometer to perform atomic emission spectrometry has been developed using the PROLOG language. The expert system can be “taught” the elemental composition of a given sample type. It uses this information (when available) to generate a line-search strategy which minimises the number of lines that need to be measured. The rules used by the system can be observed during system operation to allow a trace of the logic. Reading of the initial database takes no more than 6 s and then decisions are made in less than 1 s per line.

Application of a rapid scanning spectrometer to study on behaviors of Mn atoms and ions in an Ar-He capacitively coupled microwave plasma.

Application of a rapid scanning spectrometer to study on behaviors of Mn atoms and ions in an Ar-He capacitively coupled microwave plasma.

A photodetector-synchronized rapid scanning spectrometer with a rotating grating directly driven by a synchronous motor.

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.

Stellar spectrophotometry with a microcomputer based, intensified, silicon vidicon

We have developed several detector systems for use in observational astronomy. These include a rapid scanning spectrometer (Jeffers and Weller, 1973), a rapid chopping spectrophotometer (Stiff and Jeffers, 1978) and an intensified, silicon vidicon detector for use either for spectrophotometry (Jeffers, Stiff and Weller, 1983) or direct imaging (Jeffers, 1982). These detector systems have been used for rapid variability studies of emission line strengths and profiles in Wolf-Rayet and Of stars (Weller and Jeffers, 1979; Jeffers, Stiff and Weller, 1985) and for low dispersion spectrophotometry of these stars (Jeffers and Weller, 1985). Here we report on the spectrophotometric performance of the intensified, silicon vidicon detector (RCA 4804H) when used with a low dispersion spectrograph.

Time Resolved Optical Spectra from MIG Welding Arc Ignitions

Optical radiation from MIG (GMAW) welding arc ignitions has been measured with a rapid scan spectrometer. The time resolved spectral measurements reveal a substantial overshoot of ultraviolet radiation during the ignition phase of a 200 A aluminum arc. Calculations which follow the ACGIH guidelines show that, at a welding current of 300 A, the unprotected eye at a distance of 0.5 m may suffer a “flash” after the reception of radiation from only one ignition.

Simultaneous multi-element determination by inductively coupled plasma-rapid scanning atomic-emission spectrometry

The development of a rapid scanning spectrometer as a multi-element detector has been recently reported. In this instrument the introduction of an oscillating mirror in the optical path of a monochromator facilitated rapid scanning of a pre-selected spectral region (up to 60 nm) across the exit slit. This paper describes the results obtained when the spectrometer was coupled to an inductively coupled plasma for simultaneous multi-element determination by atomic-emission spectrometry. Detection limits are in the low-p.p.b. and sub-p.p.b. ranges and linear dynamic ranges are at least four orders of magnitude. Spinach digests were analysed for Mn and Fe and the determined values correlated well with values obtained on a polychromator system. Mn, Fe and Cu were quantified in NBS SRM bovine liver and the results compared well with the certified values.

Development of a rapid scanning spectrometer for gas chromatography with microwave induced plasma emission detection

A microwave induced plasma emission rapid-scanning spectrometer (up to 20 spectra per s) was explored for its potential as a chromatographic detector. Both hardware and software were developed which allow experimental control, data acquisition, and subsequent data reduction. Signal-to-noise enhancement as a function of scan number with or without data smoothing were explored. Data smoothing enhanced S/N. In addition, a spectrum produced by rapidly scanning the He MIP emission was compared with one taken in the normal manner by slowly scanning the grating. Point by point comparisons are good and as expected, considering that over the wavelength region scanned some light was imaged off the grating at the ends of the region resulting in some intensity changes. Integrated spectral chromatograms were obtained for Citex BC-26 at both chlorine and bromine lines. Data obtained over this region show results comparable to those attainable from experiments done with the monochromator monitoring a single line. With some modifications in the chromatography-plasma interface improvements from sub-microgram to nanogram in lowest levels detectable are expected.

A versatile low-temperature stopped-flow instrument compatible with both rapid and slow scanning spectrometers

A low-temperature stopped-flow instrument has been constructed which consists of a Teflon stopped-flow module and a quartz observation cell that are held between two halves of a contoured brass cooling block. The temperature of the system is controlled by pumping precooled methanol through channels in the cooling block, and the exposed surfaces of the observation cell are kept free of frost with a stream of precooled dry nitrogen. The instrument is versatile, compact, and can be operated over the range −55 to 25°C without leaks or optical artifacts in three modes. First, it serves as a conventional stopped-flow instrument using light of fixed wavelength to follow the progress of the reaction. In the second mode, the instrument is interfaced to a rapid scan spectrometer that uses an intensified photodiode array detector and optical multichannel analyzer to obtain time-resolved spectra of reaction intermediates. The absorption spectra of compounds I and II formed during the reaction of horseradish peroxidase with hydrogen peroxide are time-resolved at 20.2°C in methanol/phosphate buffer (60/40, v/v%). In the third mode, the peroxidase reaction is studied at −51.4°C and the absorption spectra of the intermediates are obtained with a Varian Model 219 spectrophotometer. Since the stopped-flow instrument is compact, it is also compatible with the sample compartments of other slow-scanning laboratory spectrometers and it should facilitate the study of reaction intermediates by other forms of optical spectroscopy.

Measurement of Collision Broadening of Resonance Lines of Calcium Ion by a Low-Resolution Spectrometer

The line widths of calcium ion resonance lines broadened by argon gas are measured. Radiation from the equilibrium region behind the reflected wave in a shock-tube is studied using a rapid scanning spectrometer. A method of measuring the small broadening half-width using a relatively low-resolution spectrometer is devised. The measured broadening coefficients of 2.60(±0.81)×10-20 cm-2 for the H-line and 2.84(±0.85)×10-20 cm-2 for the K-line agree fairly well with previous results.

Computer-interfaced rapid scanning molecular absorption and emission spectrophotometer for stopped-flow studies of enzyme reactions.

An improved stopped-flow system with a rapid-scanning spectrometer permits measurement of either light absorption or emission at scan speeds of up to 150 spectra per second. The entire flow system, including valves, syringes and quartz flow cell is contained in a thermostat bath and is leak-tight from 5 to 45 degrees C. Pneumatic valves control the flow through Teflon tubing. Quartz fiber-optic light guides are used to transmit light to and from the flow cell. Experimental data are given to demonstrate the absorbance and fluorescence modes. The growth and decay of the fluorescence spectrum of NADH was followed in a reaction catalyzed by lactate dehydrogenase (LDH). The kinetics of binding of 1-anilino-8-naphthalene sulfonate (ANS) to bovine serum albumin (BSA) was studied by both scanning and fixed-wavelength fluorescence emission. The fluorescence of BSA was completely quenched within two milliseconds accompanied by an abrupt increase in the fluorescence of ANS which was followed by a slower first-order growth.

Spectroelectrochemistry in Melts: Applications to Molten Chloroaluminates

Spectroelectrochemistry is an effective approach to studies of redox chemistry in solutions. We have recently initiated UV-visible spectroelectrochemical studies in molten chloroaluminates (AlCl3-NaCl mixtures) using a silicon vidicon rapid-scan spectrometer. Electrodes made from glassy carbon foam and metal grids are used in optically transparent thin layer cells. The solute species of interest are the oxidation products of sulfur and some of the Group IVB-VIB transition metal ions. In this paper the apparatus and the initial results are described.

Succinate oxidation by coupled potato tuber mitochondria followed by rapid scan spectrometry

AbstractOxidation of succinate by potato tuber mitochondria has been investigated from aerobiosis to complete anuerobiosis. Difference spectra of the various steps were recorded by a rapid scan spectrometer delivering averaged spectra every 3 s in the range 380 to 630 mm.The transitions between state 3 and 4 resulted in large redox changes, essentially for the b cytochromes, and in significant changes in the spectral baseline (light scattering). At anaerobiosis the cytochromes c, c1 and a were reduced while cytochrome a, remained oxidized. – Addition of uncouplers in aerobiosis induced oxidation of the b cytochromes, and when anaerobiosis occurred cytochromes c, c1a and a3 were reduced simultaneously. When uncouplers were added in anaerobiosis a partial oxidation of the b cytochromes and the reduction of cytochrome a3 were observed.These results are interpreted as the building up of a membrane potential, maximal in state 4 and stable after anaerobiosis. The cytochromes buried in the membrane equilibrate with the membrane potential, and their redox states are sensitive to the changes. Variations of membrane potential also induce changes in the light scattering by the mitochondrial membrane.

Spectroelectrochemistry in Melts: Applications to Molten Chloroaluminates

not Available.

Kinetic and spectroscopic studies with a rapid-scanning spectrometer. Part 2. Intermediates in the one-equivalent metal ion oxidation of phenothiazine and phenoxazine

The one-equivalent oxidations of phenothiazine and phenoxazine (Ar2NH) in neutral and acidic CH3CN solution by CeIV and FeIII have been analysed kinetically into the sequence Ar2NH [graphic omitted] Ar2NH˙+ [graphic omitted] Ar2N+→ product and values (or limits) for the relevant rate constants, including those for the oxidant–cation radical reaction, obtained by stopped-flow or rapid-scanning spectrometry. The latter technique has provided u.v.–visible spectra of all the intermediates involved, of which some are described for the first time.

ChemInform Abstract: KINETIC AND SPECTROSCOPIC STUDIES WITH A RAPID SCANNING SPECTROMETER. PART 1. RANSIENT INTERMEDIATES IN THE DISSOCIATION OF NICKEL(II) POLYAMINE COMPLEXES

Chemischer InformationsdienstVolume 10, Issue 52 Organoelement Compounds ChemInform Abstract: KINETIC AND SPECTROSCOPIC STUDIES WITH A RAPID SCANNING SPECTROMETER. PART 1. RANSIENT INTERMEDIATES IN THE DISSOCIATION OF NICKEL(II) POLYAMINE COMPLEXES T. J. KEMP, T. J. KEMPSearch for more papers by this authorP. MOORE, P. MOORESearch for more papers by this authorG. R. QUICK, G. R. QUICKSearch for more papers by this author T. J. KEMP, T. J. KEMPSearch for more papers by this authorP. MOORE, P. MOORESearch for more papers by this authorG. R. QUICK, G. R. QUICKSearch for more papers by this author First published: December 25, 1979 https://doi.org/10.1002/chin.197952273Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue52December 25, 1979 RelatedInformation