Diffusion and Heterogeneous Reaction. X. Diffusion Coefficient Measurements of Atomic Oxygen through Various Gases

Yolles, Robert S.; Wise, Henry

doi:10.1063/1.1668181

Cited by 47 publications

(6 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Comparison between Measured Diffusion Coefficients of HO x and Measured Diffusion Coefficients of Polar and Nonpolar Analogues. In the past, researchers have used the diffusion coefficients of O and O 2 (nonpolar analogues for OH and HO 2 , respectively) to approximate the diffusion coefficients of OH and HO 2 . , In Table we compare our measured diffusion coefficients of HO x with the measured diffusion coefficients of the nonpolar analogues (O and O 2 ) − ,− as well as measured diffusions coefficients of the polar analogues (H 2 O and H 2 O 2 ). − The measured diffusion coefficients for OH in He are in much better agreement with the polar analogue (H 2 O) than the nonpolar analogue (O). The measured diffusion coefficient for OH in air also appears to follow a similar trend, although definitive conclusions are not possible due to the large uncertainty in the measured diffusion coefficients of H 2 O in air.…”

Section: Resultsmentioning

confidence: 76%

“…b Based on refs −23, we have not considered the data reported in reference 31 when determining this range due to the criticisms reported in reference 22. c Based on refs −42. d Based on the diffusion in O 2 reported in refs , , [note, the diffusion in O 2 is expected to be within a few percent of the diffusion in air]. e Based on refs −36.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

OH, HO₂, and Ozone Gaseous Diffusion Coefficients

et al. 2007

View full text Add to dashboard Cite

The diffusion of OH, HO2, and O3 in He, and of OH in air, has been investigated using a coated-wall flow tube reactor coupled to a chemical ionization mass spectrometry. The diffusion coefficients were determined from measurements of the loss of the reactive species to the flow tube wall as a function of pressure. On the basis of the experimental results, D(OH-He) = 662 +/- 33 Torr cm2 s-1, D(OH-air) = 165 +/- 20 Torr cm2 s-1, D(HO2-He) = 430 +/- 30 Torr cm2 s-1, and D(O3-He) = 410 +/- 25 Torr cm2 s-1 at 296 K. We show that the measured values for OH and HO2 are in better agreement with measured values of their polar analogues (H2O and H2O2) compared with measured values of their nonpolar analogues (O and O2). The measured value for OH in air is 25% smaller than that for O (the nonpolar analogue). The difference between the measured value for HO2 and O2 (the nonpolar analogue) in air is expected to be even larger. Also we show that calculations of the diffusion coefficients based on Lennard-Jones potentials are in excellent agreement with the measurements. This gives further confidence that these calculations can be used to estimate accurate diffusion coefficients for conditions where laboratory data currently do not exist.

show abstract

Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

OH, HO₂, and Ozone Gaseous Diffusion Coefficients

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The density on the electrode surface is set to 0. The diffusion coefficient of O in ambient O 2 is set based on reported data [21] and is 0.205 m 2 s −1 at 100 mTorr. The initial n O is set constant from z = 5 to 25 mm, and the density distribution in front of the electrodes is taken to be a sinusoidal waveform in order to suppress the vibration of the density due to the steep density gradient.…”

Section: Diffusion Modelmentioning

confidence: 99%

Influence of driving frequency on oxygen atom density in O₂radio frequency capacitively coupled plasma

Kitajima¹,

Noro²,

Nakano³

et al. 2004

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

The influence of the driving frequency on the absolute oxygen atom density in an O2 radio frequency (RF) capacitively coupled plasma (CCP) was investigated using vacuum ultraviolet absorption spectroscopy with pulse modulation of the main plasma. A low-power operation of a compact inductively coupled plasma light source was enabled to avoid the significant measurement errors caused by self-absorption in the light source. The pulse modulation of the main plasma enabled accurate absorption measurement for high plasma density conditions by eliminating background signals due to light emission from the main plasma. As for the effects of the driving frequency, the effect of VHF (100 MHz) drive on oxygen atom production was small because of the modest increase in plasma density of electronegative O2 in contrast to the significant increase in electron density previously observed for electropositive Ar. The recombination coefficient of oxygen atoms on the electrode surface was obtained from a decay rate in the afterglow by comparison with a diffusion model, and it showed agreement with previously reported values for several electrode materials.

show abstract

“…The radial concentration gradients (AC/C) are estimated from Acjc N rz(k, + 3kw)/8D, where AC is the concentration gradient between the center and wall of the tube, k, and k, are effective first order constants for volume and wall removal of atoms, r. the tube radius and D is the diffusion coefficient (Kaufman, 1961). For the case here k, >> k, and D + 500 cm* s-' at 1 torr (Yolles and Wise, 1968) which gives AC/C m 0.16. The atoms are considered to be nearly uniformly distributed across the diameter of the tube.…”

Section: Calibrationmentioning

confidence: 99%

The measurement of atomic oxygen in the mesosphere and lower thermosphere

Sharp

1991

Planetary and Space Science

View full text Add to dashboard Cite

A discussion of the laboratory calibration, calibration simulation, and accuracy of a resonance fluorescence instrument for measuring oxygen atoms is given. The discussion demonstrates that a sensor can be calibrated with good accuracy to obtain in situ measurements of the oxygen density in the mesosphere/lower thermosphere. Oxygen data are reported from six rocket flights. These data represent four midlatitude flights and two aurora1 Sights. There are two night and two day profiles for the midlatitude experiments. The maximum densities found from these sets of data in the 9ClOO km regions are between 1.5x 10" cm-' and 3.5 x 10" ctn3. Agreement with the MSIS-86 model predictions is obtained for altitudes above 120 km for midlatitude flights. The aurora1 data are less than the model prediction by about a factor of 2. The data show structure that is nrobably indicative of gravity wave effects of a nominal 5 km vertical wavelength.

show abstract

Diffusion and Heterogeneous Reaction. X. Diffusion Coefficient Measurements of Atomic Oxygen through Various Gases

Cited by 47 publications

References 6 publications

OH, HO₂, and Ozone Gaseous Diffusion Coefficients

OH, HO₂, and Ozone Gaseous Diffusion Coefficients

Influence of driving frequency on oxygen atom density in O₂radio frequency capacitively coupled plasma

The measurement of atomic oxygen in the mesosphere and lower thermosphere

Contact Info

Product

Resources

About

Diffusion and Heterogeneous Reaction. X. Diffusion Coefficient Measurements of Atomic Oxygen through Various Gases

Cited by 47 publications

References 6 publications

OH, HO2, and Ozone Gaseous Diffusion Coefficients

OH, HO2, and Ozone Gaseous Diffusion Coefficients

Influence of driving frequency on oxygen atom density in O2radio frequency capacitively coupled plasma

The measurement of atomic oxygen in the mesosphere and lower thermosphere

Contact Info

Product

Resources

About

OH, HO₂, and Ozone Gaseous Diffusion Coefficients

OH, HO₂, and Ozone Gaseous Diffusion Coefficients

Influence of driving frequency on oxygen atom density in O₂radio frequency capacitively coupled plasma