The determination of cross-sections for the quenching of resonance radiation of metal atoms. V. Results for lead

1969 ◽  
Vol 313 (1515) ◽  
pp. 551-564 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Cross Sections ◽  
Intensity Distribution ◽  
Equilibrium Distribution ◽  
Metal Atoms ◽  
The Cross ◽  
Equilibrium Effect ◽  
Non Equilibrium

The flame fluorescence method has been used to determine the cross-sections for the collisional de-excitation of lead atoms from the first resonance level (6p7s 3 P 0 1 ) by hydrogen, oxygen, water, nitrogen, carbon dioxide, carbon monoxide, argon and helium. The values obtained for the cross-sections—the square of the collision diameter—are (in 10 -16 cm 2 units) σ 2 H 2 = 0.4 ± 0.1, σ 2 O 2 , = 15 ± 3, σ 2 N 2 = 5.7 ± 0.5, σ 2 H 2 O = 8 ± 2, σ 2 CO = 13 ± 3, σ 2 CO 2 = 29 ± 5, σ 2 Ar ≈ 0 ( < 1.6), σ 2 He ≈ 0 (< 0.6). The interpretation of these overall quenching cross-sections in terms of the various possible quenching processes is discussed. For some flames the fluorescence has been resolved into the component wavelengths— 405.8, 368.3, and 364.0 nm—and found to have a non-equilibrium distribution of intensities. An additional non-equilibrium effect on the intensity distribution which is attributable to chemi-excitation of lead atoms in the flames is described and discussed. The apparatus previously used is modified; the high intensity hollow cathode lead lamp used is described.

The determination of cross sections for quenching of resonance radiation of metal atoms III. Results for thallium

1968 ◽  
Vol 303 (1475) ◽  
pp. 467-475 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Cross Section ◽  
Cross Sections ◽  
Rate Constants ◽  
Resonance Radiation ◽  
Metal Atoms ◽  
The Cross

The intensity of fluorescence of thallium has been measured in hydrogen-oxygen flames diluted with each of the gases, argon, helium, nitrogen and carbon dioxide and the measurements used to obtain the following values for the quenching cross section (Å 2 ) for the 7 s 2 S ½ state of thallium σ 2 H 2 = 0.03, σ 2 O 2 = 13.2 ± 1.5, σ 2 N 2 = 6.4 ± 0.2, σ 2 H 2 O = 1.75 ± 0.2, σ 2 CO = 13.6 ± 0.8, σ 2 CO 2 = 32.5 ± 1.5, σ 2 Ar ≤ 0.1, σ 2 He ≤ 0.12. These values for the cross sections have been used to re-calculate the rate constants of the reactions, Tl + H + X → H X + Tl*, where X = H, OH, Cl or Br, from the data obtained by Phillips & Sugden (1961). The re-calculated values are lower than the original ones by a factor of 2.2.

The determination of cross sections for the quenching of resonance radiation of metal atoms II. Results for potassium, rubidium and caesium

1968 ◽  
Vol 303 (1475) ◽  
pp. 453-465 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Cross Sections ◽  
Resonance Radiation ◽  
Fluorescence Technique ◽  
Metal Atoms

The flame fluorescence technique has been used to study the fluorescence of the metals potassium, rubidium and caesium. Measurements of the intensity of fluorescence of each of these metals in isothermal groups of hydrogen-oxygen flames diluted with each of the gases argon, helium, nitrogen and carbon dioxide have given the following values (Å 2 ) for the square of the distance between the centres of colliding species, σ 2 : for potassium: σ 2 H 2 = 1.03 ± 0.05 σ 2 H 2 O = 0.9 ± 0.3 σ 2 Ar < 0.2 σ 2 He < 0.08 σ 2 N 2 = 5.6 ± 0.3 σ 2 CO = 12.4 ± 0.8 σ 2 CO 2 = 21.4 ± 1.0 σ 2 O 2 = 15.5 ± 1.5 for rubidium: σ 2 H 2 = 0.61 ± 0.1 σ 2 H 2 O = 1.27 ± 0.15 σ 2 Ar < 0.3 σ 2 He < 0.11 σ 2 N 2 = 6.1 ± 0.6 σ 2 CO = 11.8 ± 2.0 σ 2 CO 2 = 24 ± 2 σ 2 O 2 = 25 ± 5 for caesium: σ 2 H 2 = 1.7 ± 0.3 σ 2 H 2 O = 5.5 ± 1.6 σ 2 Ar < 0.9 σ 2 He < 0.4 σ 2 N 2 = 25 ± 6

The determination of cross-sections for the quenching of resonance radiation of metal atoms. IV. Results for lithium

1968 ◽  
Vol 306 (1486) ◽  
pp. 413-421 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Cross Section ◽  
Cross Sections ◽  
Hollow Cathode ◽  
Alkali Metals ◽  
Resonance Radiation ◽  
The Other ◽  
Fluorescence Technique ◽  
Metal Atoms

The flame fluorescence technique has been used to study the fluorescence of lithium in sets of isothermal hydrogen-oxygen flames diluted with each of the gases argon, nitrogen and carbon dioxide. The measurements have given the following values (Å 2 ) for the quenching cross-sections, σ 2 , of lithium in the 2 p 2 P state: σ 2 H 2 = 5⋅2, σ 2 H 2 O ═ 1⋅9, σ 2 N 2 ═ 6⋅75, σ 2 CO ═ 12⋅6, σ 2 CO 2 ═ 9⋅2, σ 2 Ar ≼ 0⋅3. The cross-section is defined as the square of the distance between centres of colliding species. These values are compared with those previously reported (Jenkins 1966, 1968) for the other alkali metals and their interpretation discussed. Details of the high intensity hollow cathode lamp used as a source of lithium resonance radiation are also given.

The determination of cross sections for the quenching of resonance radiation of metal atoms I. Experimental method and results for sodium

1966 ◽  
Vol 293 (1435) ◽  
pp. 493-511 ◽  
Keyword(s):  
Experimental Method ◽  
Cross Sections ◽  
Resonance Radiation ◽  
Line Broadening ◽  
Compound Formation ◽  
Metal Atoms ◽  
Sodium Atoms ◽  
The Cross ◽  
Oxygen Flame

A method of determining the cross sections for the quenching of excited metal atoms by molecules and atoms which may be present in flames is described. The method has been applied to the quenching of sodium atoms in the 3 p 2 P state and the following results (in Å 2 ) for the square of the distance between the centres of colliding species, σ 2 , obtained: σ 2 H 2 = 2.87 ± 0.1; σ 2 N 2 = 6.95 ± 0.15; σ 2 CO = 11.9 ± 0.4; σ 2 CO 2 = 17.0 ± 0.4; σ 2 H 2 O = 0.5 ± 0.3; σ 2 O 2 = 12.3 ± 0.5; σ 2 Ar < 0.1; σ 2 He < 0.1. These cross sections have been measured at temperatures in the range 1400°K to about 1800°K and found to be independent of the temperature. The values for the cross sections are derived from measurements of the fluorescence of sodium in hydrogen-oxygen flame diluted with various other gases. This method is believed to be free of uncertainties due to self-absorption, compound formation, line broadening effects and uncertain velocity distributions. Where values for cross sections have been obtained by other workers they are compared with these results and possible reasons for the discrepancies are discussed.

RUMEN GAS ANALYSIS BY GAS-SOLID CHROMATOGRAPHY

1961 ◽  
Vol 41 (2) ◽  
pp. 187-196 ◽  
Author(s):  
J. M. McArthur ◽  
J. E. Miltimore
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Hydrogen Sulphide ◽  
Sample Volume ◽  
Gas Analysis ◽  
Complete Analysis ◽  
Thermal Detector ◽  
Thermal Detection ◽  
Methane Carbon

Methods are described for sampling and analysing rumen gases. The analysis requires less than 15 minutes for the determination of hydrogen, oxygen, nitrogen, methane, carbon monoxide, carbon dioxide, and hydrogen sulphide, i.e., for all gases occurring in the rumen. The method is sensitive and requires only a small quantity of sample, and the sample volume need not be known. The presence of water or other vapours in the sample does not influence the results. Relative thermal detector responses have been determined for gases which occur in the rumen. These eliminate the necessity for the calibration of gas chromatographs using thermal detection. The first complete analysis of rumen gas is presented.

scholarly journals The Use of Cryogenic Temperature Gas Chromatography for the Determination of Carbon Monoxide and Carbon Dioxide in Cigarette Smoke

1972 ◽  
Vol 6 (4) ◽  
Author(s):  
G.P. Morie ◽  
C.H. Sloan
Keyword(s):  
Carbon Dioxide ◽  
Gas Chromatography ◽  
Carbon Monoxide ◽  
Liquid Nitrogen ◽  
Cigarette Smoke ◽  
Cryogenic Temperature ◽  
Chromatographic Method ◽  
Porapak Q ◽  
Gas Chromatographic Method

AbstractA gas chromatographic method for the determination of carbon monoxide and carbon dioxide in cigarette smoke was developed. A column containing Porapak Q packing and a cryogenic temperature programmer which employed liquid nitrogen to cool the column to subambient temperatures was used. The separation of N

scholarly journals Diffusion and chemical reaction velocity as joint factors in determining the rate of uptake of oxygen and carbon monoxide by the red blood corpuscle

1932 ◽  
Vol 111 (769) ◽  
pp. 1-36 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Cross Sections ◽  
The Other ◽  
Blood Corpuscle ◽  
Reaction Velocity ◽  
Two Fluids ◽  
Mixing Chamber ◽  
Haemoglobin Solution ◽  
Moving Fluid

In a paper on this subject published four years age, Hartridge and Roughton (1927) described some preliminary experiments upon the rate of uptake of oxygen and carbon monoxide by the red blood corpuscle, the observations being made by means of their reaction velocity technique (Hartridge and Roughton, 1922–1927). The general principles of the method were as follows. Through one lead of the apparatus a suspension of reduced corpuscles in saline was forces into the mixing chamber, whilst through the other lead was forced a solution of oxygen (or carbon monoxide) in saline. The two fluids mixed in the mixing chamber within 0·001 second or less and then travelled down the observation tube. Determination of the percentage of oxyhæmoglobin (or carboxyhæmoglobin) in the moving fluid at various cross sections of the observation tube was made by means of the reversion spectroscope, these measurements, together with a knowledge of the rate of flow of the fluid down the observation tube, giving the necessary data for plotting the rate of uptake of O 2 or CO by the corpuscles against time. The most interesting feature of the results was the much slower uptake of O 2 by hæmoglobin in the intact corpuscle as compared with the of O 2 by hæmoglobin in laked solution as previously recorded by Hartridge and Roughton (1925). In the corpuscle experiments the time scale had to be expressed in hundredths of a second instead of in thousandths of a second as in the hæmoglobin solution experiments ( vide fig. 2 of Hartridge and Roghton, 1927). Confirmatory results by somewhat different technique have been obtained lately by Dirken and Mook (1931). These will be referred to again later.

The determination of the cross sections for the reactions 27 Al( n , α ) and 56 Fe( n , p ) for 14 MeV neutrons by an absolute method

1966 ◽  
Vol 292 (1429) ◽  
pp. 180-192 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Standard Error ◽  
Particle Method ◽  
Systematic Errors ◽  
Aluminium Foil ◽  
The Mean ◽  
The Cross ◽  
Experimental Values

Measurements of the cross sections for the reactions 27 Al( n , α ) 24 Na and 56 Fe( n, p ) 56 Mn for neutrons of energy 13.5 ± 0.1 MeV have been made by a radioactivation method. The neutron flux was determined by a variant of the 'associated particle’ method, in which the α -particles produced concurrently with the neutrons from the D + T reaction were estimated in terms of the volume of helium which accumulated when they were brought to rest in an aluminium foil. Cross section values obtained at 13.5 MeV were: for 27 Al( n , α ): 118.1 ± 6.0 mb : for 56 Fe( n, p ): 106.7 ± 4.7 mb. The errors quoted include both the standard error on the mean of the experimental values and an estimate of possible residual systematic errors. The excitation functions for both reactions in the energy region 13.5 to 14.8 MeV have also been investigated, in order to provide secondary cross section values over this range of energies. At 14.8 MeV the values found were: 27 Al( n , α )103.6 ± 5.5 mb; 56 Fe( n, p )96.7 ± 4.5 mb.

scholarly journals Photolysis of diatomic molecules as a source of atoms in planetary exospheres

2020 ◽  
Vol 633 ◽  
pp. A39 ◽  
Author(s):  
R. R. Valiev ◽  
A. A. Berezhnoy ◽  
I. S. Gritsenko ◽  
B. S. Merzlikin ◽  
V. N. Cherepanov ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Quantum Chemistry ◽  
Cross Sections ◽  
Diatomic Molecules ◽  
Astronomical Unit ◽  
Quiet Sun ◽  
Metal Atoms ◽  
The Cross ◽  
Planetary Exospheres

We calculated the cross sections of photolysis of OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF molecules using quantum chemistry methods. The maximal values for photolysis cross sections of alkali metal monoxides are on the order of 10−18 cm2. The lifetimes of photolysis for quiet Sun at 1 astronomical unit are estimated as 2.0 × 105, 28, 5, 14, 2.1 × 105, 225, 42, 52, 2 × 106, 35 400, 486, and 30 400 s for OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF, respectively. We performed a comparison between values of photolysis lifetimes obtained in this work and in previous studies. Based on such a comparison, our estimations of photolysis lifetimes of OH, HCl, and HF have an accuracy of about a factor of 2. We determined typical kinetic energies of main peaks of photolysis-generated metal atoms. Impact-produced LiO, NaO, KO, NaCl, and KCl molecules are destroyed in the lunar and Hermean exospheres almost completely during the first ballistic flight, while other considered molecules are more stable against destruction by photolysis.

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