Analytical Flame Spectroscopy

Alkemade, C.Th.J.; Bleekrode, R.; Burger, Joanna; Butler, Constance C.; Cath, P. G.; Fassel, Velmer A.; Gilbert, Paul; Gillies, W.; Herrmann, Roland; Kniseley, Richard N.; Mavrodineanu, R.; Menis, Oscar; Müller-Herget, W.; Pinta, Maurice; Rains, T. C.; Smith, Robin; Willis, J. B.; Winefordner, J. D.; Yamasaki, G. K.

doi:10.1007/978-1-349-01008-0

Cited by 26 publications

(21 citation statements)

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“…The fact that the integrated intensities reach maximum or limiting values in a nearly isothermal region of the flame suggests that volatilization at least is complete (7). When more refractory species are introduced in a flame, a steady increase in analyte emission intensity with increasing distance above the primary reaction zone frequently is observed if intensities are corrected for thermal gradients in the flame (17). This has been at- It is interesting to note that the peak intensities along the flame axes for both Ca and Mn decrease with increasing height in the plume even near the plume origin where the integrated intensity plots indicate that free atom production is still occurring.…”

Section: Resultsmentioning

confidence: 99%

Mass-action controlled ionization of individual solute vapor clouds in flame spectrometry

Joshi¹,

Sacks²

1979

Anal. Chem.

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A stream of nearly identical droplets of CaCI, or Mn(N-0,),-4H20 solution is introduced along the axis of a N,0-C2H, flame supported on a circular slot burner. Radial scans of the emission intensity of Ca and Mn at various heights in the vapor cloud are used to obtain information on the size and shape of the cloud as well as on changes in the total number of emitting species with height in the cloud. Results for Ca show a more than 50 YO decrease in intensity 70 mm above the origin of the vapor cloud relative to 19 mm where the intensity is maximum. It is shown that much of this decrease in neutral-atom line intensity can be accounted for by the effect of mass action on ionization as the vapor clouds from the individual solute particles expand by isotropic diffusion. Further, it is shown that diffusion is slow relative to convection as a mass transport process. This permits the extension of the mass-action controlled ionization concept to conventional nebulizers, where ionizatlon interference frequently is observed to increase with increasing height above the primary reaction zone in the flame.Because of the relatively high temperature of the NzO-C2H2 flame, ionization interferences are frequent and often severe (1-3). Values of degree of ionization of 83% and 9% for Ca and Mn, respectively, were reported by Kornblum and deGalan ( I ) . They also reported greater ionization 10 mm above the burner head than at 4 m m for a 5-cm slot burner. This was attributed to a relaxation effect from kinetically controlled ionization.Ionization interferences generally are observed to increase with increasing height in the flame above the primary reaction zone (1,4-7). This has been observed for both circular and slot burners and has been attributed to a decrease in electron partial pressure with increasing distance from the primary reaction zone (8) and, more frequently, to kinetically controlled ionization processes (1, 5 , 7 ) .Ashton and Hayhurst (9) presented a diffusion model for a point source of free atoms in Hz-O2-NZ flames. Their model accounted for metal atom loss through ionization by assuming a first-order, rate controlled ionization process. They assumed that the free electron partial pressure, as well as that of the metal ion, was so low that the reverse or recombination reaction could be neglected. Clearly, this is not the case in the higher temperature N20-C2H2 flame, where ionization of metals may be extensive and the electron partial pressure in the unsalted flame may be as high as lo4 atm well above the primary reaction zone ( 2 ) .Bastiaans and Hieftje ( 7 ) , in a study of individual solute particles in an air-CzHz flame, observed -15% decrease in Ca neutral-atom line intensity a t 8 cm above the vapor plume origin relative to 2 cm. Their experimental arrangement permitted all measurements to be made at the same height in the flame, thereby minimizing problems associated with axial temperature gradients in the flame. The decrease in Ca free atom population was attributed to kinetically controlled ionization...

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Section: Resultsmentioning

confidence: 99%

Mass-action controlled ionization of individual solute vapor clouds in flame spectrometry

Joshi¹,

Sacks²

1979

Anal. Chem.

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“…The reaction is associated with the decomposition of metal oxides in fire to produce electrons according to the reaction [15]:…”

Section: Ionisation In the Firementioning

confidence: 99%

“…In reactions where chlorine is in co-existence with alkali metals such as sodium, it may play a catalytic role in ionization of the latter by hydrogen atoms to produce electrons and metal ions. The process occurs according to the reaction equation [15]:…”

Section: Ionisation In the Firementioning

confidence: 99%

Absorption of Microwaves in Low Intensity Eucalyptus Litter Fire

Letsholathebe¹,

Mphale²

2015

JEMAA

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A fuel bed was constructed where various vegetation species could be used as combustion fuel. The fuel bed was equipped with a thermocouple to measure fire temperature and a two-port automatic network analyser to measure microwave scattering parameters in flame medium. The parameters are then used to determine microwave propagation characteristics in fire. The measurements have implications on radio wave communication during wildfire suppression and in remote sensing. The attenuation data also provide an estimation of vegetation fire ionisation and conductivity. Eucalyptus litter fire with a maximum flame temperature of 976 K was set on the fuel bed and X-band microwaves (7.00 -9.50 GHz) were caused to propagate through the flame. Attenuation of 0.35 -0.90 dB was measured for microwaves in the frequency range. For the low intensity fire, conductivity was measured to range from 0.00021 -0.00055 mho/m and electron density was to be the range of 1.83 -2.24 × 10 15 m −3 .

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“…The total energy can be expressed as the sum of the different kinds of energy possessed by these molecules as shown in Eq. (1).…”

Section: Introductionmentioning

confidence: 99%

OH Emission Spectra of Hybrid Rocket Motors Using PMMA

Wilson¹,

Mackey²,

Keller³

et al. 2005

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Our goal is development of diode laser sensors that monitor hybrid rocket motor emissions in the near-infrared. Quantities desired from the measurements are temperature, molecule number density, pressure and velocity. Targeted species include carbon dioxide, water and OH radicals. The measuring instrumentation will become part of the rocket motor control system to optimize thrust, fuel efficiency and safety response. To validate OH radical information gathered from the near-infrared region using diode lasers, studies are being conducted that measure OH radical emission spectra in the ultraviolet region, 305 to 330 nm that includes the A 2 S + ,? = 0? X 2 ? + , ?' = 0 band. Two compact spectrometers, having 590 grooves/mm and 3600 grooves/mm gratings and 2048 pixel CCD line camera detectors were controlled with software that performed synchronous, repetitive spectral capture. Spectra were acquired by the spectrograph through an armored 400 µm fiber optic cable, 2 m long, terminated with a UV collimating lens pointing towards the rocket exhaust. The lens was mounted in one end of a black Delrin cylinder 100 mm long having a 6 mm bore, allowing investigation of 8 mm 2 segments of the rocket plume. A test stand was designed to allow precise control of experimental parameters. Simple adjustments of the test stand made it possible to rapidly measure different parts of the plume. The design included provision for simultaneous recording of UV, Vis and NIR spectra of the same part of the rocket plume. The exhaust plumes from PMMA, polymethylmethacrylate, fuel grains were mapped spatially and temporally. Several investigators have modeled the spectrum of OH radicals in order to determine the combustion temperatures of different processes. Their methods were employed to characterize hybrid rocket plume emissions. Temperatures estimated for the PMMA fuel grains ranged from 2600 to 3400 K using 5 to 30 psig oxygen. 11measuring distance from the exit end of the fuel grain. Under the condition of 20 psig oxygen pressure, the maximum amount of OH, indicated by intensity of emission at 306-320 nm is found at 24 mm.

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Analytical Flame Spectroscopy

Cited by 26 publications

References 0 publications

Mass-action controlled ionization of individual solute vapor clouds in flame spectrometry

Mass-action controlled ionization of individual solute vapor clouds in flame spectrometry

Absorption of Microwaves in Low Intensity Eucalyptus Litter Fire

OH Emission Spectra of Hybrid Rocket Motors Using PMMA

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