PRIMARY PROCESSES IN REACTIONS INITIATED BY PHOTOEXCITED MERCURY ISOTOPES

1958 ◽  
Vol 36 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Harry E. Gunning
Keyword(s):  
Water Vapor ◽  
Hydrogen Chloride ◽  
Methylene Chloride ◽  
Methyl Chloride ◽  
Mercury Vapor ◽  
Enrichment Factors ◽  
Exchange Reactions ◽  
Boron Trichloride ◽  
Mercury Compounds ◽  
Similar Enrichment

A study has been made of the reaction of Hg2026(3P1) atoms, photoexcited in natural mercury vapor; with a number of substrates which form solid mercury compounds in mercury photo-sensitization. Some data are also given for reactions initiated by Hg1986(3P1) atoms. The solid mercury compounds formed were examined for enrichment in the isotope initiating the reaction. Such enrichment would be evidence for the primary formation of the mercury compound.Three HgO-forming substrates were studied: water vapor, nitrous oxide, and oxygen. The Hg2Cl2-forming substrates studied included hydrogen chloride, methyl chloride, methylene chloride, chloroform, carbon tetrachloride, isopropyl chloride, and boron trichloride. One Hg2Br2-forming substrate was examined—isopropyl bromide.Among the HgO-forming substrates only water vapor gave enrichment in Hg202 in the HgO product. The Hg202 content of the oxide was found to vary from 32 to 35%, depending on reaction conditions, compared to a natural abundance of 29.6%. With water vapor – butadiene mixtures, oxides containing as high as 90% Hg202 were obtained. Similar enrichment factors were obtained for Hg1986(3P1) reactions.Hydrogen chloride and the alkyl chlorides yielded calomels containing a maximum of 45% Hg202. Methyl chloride gave similar enrichment factors in Hg198 for the Hg1986(3P1) reaction. The calomel formed in the boron trichloride reaction showed no enrichment.Addends such as butadiene and benzene, when added to hydrogen chloride, increased the Hg202 enrichment from 45% to 60%.For those reactions which yield mercury compounds enriched in the initiating mercury isotope, evidence is presented for a single primary process. Failure to obtain pure isotopes is attributed to exchange reactions with adsorbed natural mercury during recovery of the enriched mercury from the product. It is postulated that the addends react with the mercury product and reduce chemisorption of natural mercury on the product.The significance of these findings in the mechanisms of the reactions studied is discussed.

PHOTOCHEMICAL SEPARATION OF MERCURY ISOTOPES: V. FURTHER STUDIES ON THE REACTION OF Hg2026(3P1) ATOMS, PHOTOEXCITED IN NATURAL MERCURY VAPOR, WITH HYDROGEN CHLORIDE

1959 ◽  
Vol 37 (9) ◽  
pp. 1432-1441 ◽  
Author(s):  
J. R. McDowell ◽  
C. C. McDonald ◽  
H. E. Gunning
Keyword(s):  
Steady State ◽  
Hydrogen Chloride ◽  
Mercury Vapor ◽  
Recovery Process ◽  
Pure Hydrogen ◽  
Exchange Reactions ◽  
Recovery Techniques ◽  
Specific Step ◽  
Recovery Technique ◽  
Mercury Recovery

A further study has been made of the reaction of Hg2026(3P1) atoms, in natural mercury vapor (HgN), with hydrogen chloride under flow conditions at room temperature. Emphasis has been placed in this study on the effect of reaction parameters and mercury-recovery techniques on the Hg202 content of the solid calomel formed in the reaction.For pure hydrogen chloride the Hg202 content of the calomel was found to be 39.9 ± 0.3%, compared to the natural abundance of 29.8%. With 20–40 mole % of butadiene-1,3 in the hydrogen chloride, calomels containing 83–84% of Hg202 were consistently obtained.The isotopically specific aspects of the reaction in pure hydrogen chloride can be adequately explained by the sequence:[Formula: see text]where M in reaction [3] is a third body or the wall. From the Hg202-abundance data and steady-state considerations, it has been shown that the ratio of partitioning of the absorbed radiation to [1] and [2], respectively, = Φ1/Φ2 = 0.40 ± 0.02. In short, 29% of the primary reaction proceeds by the isotopically specific step [1].The Hg202 content of the calomel product was found to increase markedly when unsaturated hydrocarbons were added to the hydrogen chloride stream. The addends studied included butadiene-1,3, benzene, isoprene, acetylene, propylene, and ethylene in order of decreasing effectiveness. In the presence of the unsaturated addend (U) two additional reactions were postulated to occur:[Formula: see text]From steady-state calculations the effectiveness of the addend can be shown to be determined by the rate ratio, k8/k4.For the maximally enriching mixture of hydrogen chloride and butadiene, the effect of variations in lamp temperature and reaction pressure was studied. At lamp temperatures exceeding approximately 35 °C, reduced enrichments were obtained owing to emission-line broadening. A progressive reduction in enrichment was also observed with substrate pressures greater than 25 mm, owing presumably to Lorentz-broadening of the hyperfine absorption contours of the HgN in the reaction cell.The Hg202 content of the calomel product was determined by resonance radiation absorbiometry. The apparent Hg202 abundances of the mercury recovered from the calomel product were found to depend strongly on the method used for isolating the enriched mercury from the calomel. Evidence was obtained for the occurrence of isotopically degradative exchange reactions during the recovery process. A recovery technique was developed which appeared to eliminate this exchange degradation.

scholarly journals The refraction and dispersion of some gaseous compounds

1931 ◽  
Vol 133 (821) ◽  
pp. 188-207 ◽  
Keyword(s):  
Ethyl Ether ◽  
Methylene Chloride ◽  
Methyl Chloride ◽  
Silicon Tetrachloride ◽  
Gaseous State ◽  
Boron Trichloride ◽  
Recorded Data ◽  
Boron Tribromide ◽  
State 1

In the present paper, results are given of measurements which have been made by the author on the refraction and dispersion of the following substances in the gaseous state :— (1) Silicon tetrachloride, SiCl 4 ; (2) silicon tetrabromide, SiBr 4 ; (3) boron trichloride, BCl 3 ; (4) boron tribromide, BBr 3 ; (5) phosgene, COCl 2 ; (6) acetone, (CH 3 ) 2 CO; (7) ethyl ether, (C 2 H 5 ) 2 O; (8) acetylene, C 2 H 2 ; (9) ethylene, C 2 H 4 ; (10) ethane, C 2 H 6 ; (11) methyl chloride, CH 3 Cl; (12) methylene chloride, CH 2 Cl 2 ; (13) methylene bromide, CH 2 Br 2 . The gaseous refractivities of six of these compounds (viz., silicon tetrachloride, silicon tetrabromide, boron trichloride, boron tribromide, methylene chloride, methylene bromide) have not been previously determined and the recorded data for the remaining substances are either so meagre or discordant that further determinations were obviously called for.

Diffusion of Methane and Chloromethanes in Air

1971 ◽  
Vol 49 (1) ◽  
pp. 74-77 ◽  
Author(s):  
M. Cowie ◽  
Harry Watts
Keyword(s):  
Carbon Tetrachloride ◽  
Diffusion Coefficients ◽  
Methylene Chloride ◽  
Methyl Chloride ◽  
Diffusion Cell ◽  
Infrared Spectrophotometry ◽  
Gaseous Diffusion ◽  
Simple Diffusion ◽  
Concentration Changes

The binary gaseous diffusion coefficients of air with methane, methyl chloride, methylene chloride, chloroform, and carbon tetrachloride at 298.2 °K and 1 atm have been determined. A simple diffusion cell was used, in which concentration changes of the diffusing gas were followed by infrared spectrophotometry.

scholarly journals Use of a heated graphite scrubber as a means of reducing interferences in UV-absorbance measurements of atmospheric ozone

2017 ◽  
Vol 10 (6) ◽  
pp. 2253-2269 ◽  
Author(s):  
Andrew A. Turnipseed ◽  
Peter C. Andersen ◽  
Craig J. Williford ◽  
Christine A. Ennis ◽  
John W. Birks
Keyword(s):  
Water Vapor ◽  
Solid Phase ◽  
Mercury Vapor ◽  
Packed Bed ◽  
The United States ◽  
Voc Adsorption ◽  
Clean Air ◽  
Smog Chambers ◽  
Equivalent Method ◽  
Ambient Measurements

Abstract. A new solid-phase scrubber for use in conventional ozone (O3) photometers was investigated as a means of reducing interferences from other UV-absorbing species and water vapor. It was found that when heated to 100–130 °C, a tubular graphite scrubber efficiently removed up to 500 ppb ozone and ozone monitors using the heated graphite scrubber were found to be less susceptible to interferences from water vapor, mercury vapor, and aromatic volatile organic compounds (VOCs) compared to conventional metal oxide scrubbers. Ambient measurements from a graphite scrubber-equipped photometer and a co-located Federal equivalent method (FEM) ozone analyzer showed excellent agreement over 38 days of measurements and indicated no loss in the scrubber's ability to remove ozone when operated at 130 °C. The use of a heated graphite scrubber was found to reduce the interference from mercury vapor to ≤ 3 % of that obtained using a packed-bed Hopcalite scrubber. For a series of substituted aromatic compounds (ranging in volatility and absorption cross section at 253.7 nm), the graphite scrubber was observed to consistently exhibit reduced levels of interference, typically by factors of 2.5 to 20 less than with Hopcalite. Conventional solid-phase scrubbers also exhibited complex VOC adsorption and desorption characteristics that were dependent upon the relative humidity (RH), volatility of the VOC, and the available surface area of the scrubber. This complex behavior involving humidity is avoided by use of a heated graphite scrubber. These results suggest that heated graphite scrubbers could be substituted in most ozone photometers as a means of reducing interferences from other UV-absorbing species found in the atmosphere. This could be particularly important in ozone monitoring for compliance with the United States (U.S.) Clean Air Act or for use in VOC-rich environments such as in smog chambers and monitoring indoor air quality.

PHOTOCHEMICAL SEPARATION OF MERCURY ISOTOPES: III. THE REACTION OF Hg2026(3P1) ATOMS, PHOTOEXCITED IN NATURAL MERCURY VAPOR, WITH HYDROGEN CHLORIDE

1959 ◽  
Vol 37 (5) ◽  
pp. 930-939 ◽  
Author(s):  
C. C. McDonald ◽  
J. R. McDowell ◽  
H. E. Gunning
Keyword(s):  
Emission Line ◽  
Hydrogen Chloride ◽  
Mercury Vapor ◽  
Pure Hydrogen ◽  
Hydrogen Atoms ◽  
Unsaturated Compounds ◽  
Depletion Effect ◽  
Flowing Hydrogen ◽  
Fast Flow ◽  
Static Conditions

An investigation has been made of the reaction of Hg2026(3P1) atoms, photoexcited in natural mercury vapor, with flowing hydrogen chloride at 28–30 °C. Emphasis has been placed on the effect of reaction parameters on the Hg202 content of the calomel product of the reaction.Under fast-flow conditions it has been found that the calomel product contains 44% Hg202, corresponding to an enrichment of 48% over the normal abundance of 29.8%.In the presence of unsaturated compounds such as butadiene and benzene the enrichment is markedly increased. With butadiene and benzene as addends, the maximum enrichments were 98% and 85% respectively.The reaction with pure hydrogen chloride can be explained in terms of the sequence:[Formula: see text]where HgN is natural mercury and M is a third body, including the wall.In the presence of unsaturated compounds (U), additional reactions are postulated to occur:[Formula: see text]The increased enrichment in the presence of unsaturated addends is explained by the reduced rate of formation of HgNCl through cleanup of chlorine and hydrogen atoms by reactions [6] and [7].Under static conditions, the pure hydrogen chloride reaction formed a calomel product of normal Hg202 abundance. This finding is explained as a localized depletion of the unexcited mercury in Hg202, through reaction [1]. With increasing linear flow rate the depletion effect gradually disappears and enrichments maximize at high flow rates.The Hg202 enrichment was found to be very sensitive to the wall temperature of the Hg202 source. In a 50:50 v/v mixture of hydrogen chloride and butadiene the enrichment was found to decrease from 68% to 24% as the lamp temperature was raised from 25.5 °C to 50 °C. The effect is explained by temperature broadening of the emission line leading to overlap of the emission line on absorption contours adjacent to that of Hg202.Both the rate of deposition of the calomel product and the Hg202 enrichment were found to depend upon the concentration of natural mercury in the gas stream for hydrogen chloride – butadiene mixtures. Optimum conditions corresponded to a slight supersaturation of the stream with mercury vapor.

Halomethyl-metal compounds VIII. The reaction of phenyl(trihalomethyl)mercury compounds with hydrogen chloride

1967 ◽  
Vol 8 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Dietmar Seyferth ◽  
Jeffrey Yick-Pui Mui ◽  
Lee J. Todd ◽  
Kirk V. Darragh
Keyword(s):  
Hydrogen Chloride ◽  
Metal Compounds ◽  
Mercury Compounds
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