The recombination of atoms II. Causes of variation in the observed rate constant for iodine atoms

1955 ◽  
Vol 231 (1187) ◽  
pp. 446-457 ◽  
Keyword(s):  
Rate Constant ◽  
Inert Gases ◽  
Inert Gas ◽  
Third Order ◽  
Experimental Conditions ◽  
The Third ◽  
M 10 ◽  
Linear Relationships ◽  
Real Increase ◽  
Gas Molecules

A re-investigation of the recombination of iodine atoms in presence of the inert gases over a wider range of experimental conditions has shown that the simple termolecular rate law — d(I)/d t = k (I) 2 ( M ) is not obeyed. For each of the inert gases k , the experimentally determined termolecular rate constant, increases with the ratio (I 2 )/( M ), where (I 2 ) and ( M ) are the concentrations of iodine m olecules and inert gas molecules respectively. The dependence of k on (I 2 )/( M ) was obscured in previous work by the fact that a thermal effect, which results in a lowering of the apparent value of k as recombination proceeds, increases as (I 2 )/( M ) increases and compensated for the real increase in k with (I 2 )/( M ). Except at low (I 2 )/( M ) values, k is a linear function of (I 2 )/( M ), the gradient being the same for all five inert gases. A rapid termolecular reaction I+I+I 2 =I 2 +I' 3 with a rate constant k = 470 x 10 -32 ml. 2 mol .-2 s -1 is postulated to explain the linear relationships. B y extrapolation the values of k M the third-order rate constants for the five inert gases are M 10 32 k M (ml. 2 mol. -2 s -1 ) He Ne A Kr Xe 0.67 0.92 1.84 2.25 2.99

The motion of slow positive ions in gases - Mobilities of ions in argon

1966 ◽  
Vol 259 (1100) ◽  
pp. 331-338
Keyword(s):  
Drift Velocity ◽  
Minority Group ◽  
Second Order ◽  
The Other ◽  
Third Order ◽  
The Third ◽  
Positive Ions ◽  
Majority Group ◽  
Gas Molecules

This second slower group was resolved only in the third order maxima and was present in such small numbers that its mobility could not be accurately determined. Nevertheless, when the two groups of ion are resolved in this way the correct value is obtained for the mobility of the majority group. The lower values of mobility, sometimes found when the first and second order maxima were used, were due to the perturbation of the peaks of the majority group by the unresolved minority group. This minority group had a lower drift velocity than the other group and was seen to become more predominant as the conditions were altered so that the number of collisions between the faster ions and the gas molecules was increased.

Defect structures induced by inert-gases in rapidly solidified type 304 stainless steel

1988 ◽  
Vol 46 ◽  
pp. 558-559
Author(s):  
Jung Chan Bae
Keyword(s):  
Stainless Steel ◽  
Inert Gases ◽  
Inert Gas ◽  
Water Quenching ◽  
304 Stainless Steel ◽  
Ingot Metallurgy ◽  
Dislocation Loops ◽  
Experimental Conditions ◽  
Type 304 ◽  
Type 304 Stainless Steel

Defects-are formed in most plastically deformed, quenched, and radiation damaged materials, and their type and distribution depend on the experimental conditions. Extensive research on radiation damage has shown that inert gases accumulate in materials and cause significant alterations of the microstructure and mechanical properties. In the centrifugal atomization process, the exposure of Type 304 stainless steel droplets to inert gas environments presents opportunities for their entrapment. The observation of large number density defects such as vacancy type dislocation loops and stacking faults in as-solidified Type 304 stainless steel powder is attributed to the inert gas/vacancy interaction.The purpose of this work is to examine the defect microstructure of extruded powder metallurgy (P/M) Type 304 stainless steel after preconditioning heat treatments at 900, 1000,1100, and 1200C for 1 hour followed by water quenching. Also, ingot metallurgy (l/M) Type 304 stainless steel (remnants of the feed stock for the powders) was heat treated at 1000 and 1100C for 1 hour followed by water quenching for comparison.

scholarly journals The thermal diffusion of radon gas mixtures

1942 ◽  
Vol 181 (984) ◽  
pp. 93-100 ◽  
Keyword(s):  
Force Field ◽  
Thermal Diffusion ◽  
Special Theory ◽  
Mean Value ◽  
Repulsive Force ◽  
Inert Gases ◽  
Inert Gas ◽  
Cold Side ◽  
The Mean ◽  
Gas Molecules

In continuation of earlier experiments (Harrison 1937) in which the thermal diffusion in radon-hydrogen and radon-helium mixtures was measured, the thermal diffusion of mixtures of radon-neon and radon-argon has now been studied. The mean value obtained for the ratio of the proportion by volume of radon on the cold side at 0° C to that on the hot side at 100° C, after thermal diffusion, was 1·074 for radon-neon mixtures, and 1·008 for radon-argon mixtures. In order to calculate the repulsive force field, F 12 , between these two pairs of molecules, the present results were combined with measurements of ordinary diffiisirm of radon into neon and radon into argon (Hirst & Harrison 1939), and viscosity determinations at various temperatures of neon and argon (Trautz & Binkele 1930). The special theory, due to Chapman (1929), of thermal diffusion of a rare constituent in a binary mixture was used to derive Flt. The values obtained for the repulsive force field between the dissimilar molecules at collision were: F 12 (radon-neon) = 1·9 x 10 -51 d -6·1 = ( d / d 0 ) -6·1 , d 0 = 4·8 x 10 -9 , F 12 (radon-argon) = 2·1 x 10 -43 d -5·1 = ( d 0 )-5·1 , d 0 = 4·3 x 10 -9 , d being the distance between the point centres of repulsive force and d 0 the value of d at which F 12 is 1 dyne. A comparison of the values obtained for the repulsive force index for radon-neon and radon-argon molecules with those obtained by Atkins, Bastick & Ibbs (1939) for binary mixtures of the first five inert gases shows that radon is the4 softest ’ of the inert gas molecules. Radon-argon molecules are the closest approach to the Maxwellian case yet studied experimentally.

Determination of the rate constant of formation of excited inert-gas molecules

1978 ◽  
Vol 14 (3) ◽  
pp. 284-287
Author(s):  
I. M. Belousova ◽  
Yu. I. Dymshits ◽  
A. G. Kavetskii ◽  
V. A. Korobitsyn ◽  
V. G. Neverov
Keyword(s):  
Rate Constant ◽  
Inert Gas ◽  
Gas Molecules

Decompression outcome following saturation dives with multiple inert gases in rats

1985 ◽  
Vol 59 (5) ◽  
pp. 1503-1514 ◽  
Author(s):  
R. S. Lillo ◽  
E. T. Flynn ◽  
L. D. Homer
Keyword(s):  
Decompression Sickness ◽  
Equation Model ◽  
Hill Equation ◽  
The Body ◽  
Inert Gases ◽  
Inert Gas ◽  
Albino Rats ◽  
Experimental Conditions ◽  
Decompression Stress ◽  
Relative Potencies

This investigation examined the question of whether gas mixtures containing multiple inert gases provide a decompression advantage over mixtures containing a single inert gas. Unanesthetized male albino rats, Rattus norvegicus, were subjected to 2-h simulated dives at depths ranging from 145 to 220 fsw. At pressure, the rats breathed various He-N2-Ar-O2 mixtures (79.1% inert gas-20.9% O2); they were then decompressed rapidly (within 10 s) to surface pressures. The probability of decompression sickness (DCS), measured either as severe bends symptoms or death, was related to the experimental variables in a Hill equation model incorporating parameters that account for differences in the potencies of the three gases and the weight of the animal. The relative potencies of the three gases, which affect the total dose of decompression stress, were determined as significantly different in the following ascending order of potency: He less than N2 less than Ar; some of these differences were small in magnitude. With mixtures, the degree of decompression stress diminished as either N2 or Ar was replaced by He. No obvious advantage or disadvantage of mixtures over the least potent pure inert gas (He) was evident, although limits to the expectation of possible advantage or disadvantage of mixtures were defined. Also, model analysis did not support the hypothesis that the outcome of decompression with multiple inert gases in rats under these experimental conditions can be explained totally by the volume of gas accumulated in the body during a dive.

Probe size and 5th-order aberration

1987 ◽  
Vol 45 ◽  
pp. 134-135 ◽  
Author(s):  
Zhifeng Shao
Keyword(s):  
Electron Probe ◽  
Spherical Aberration ◽  
Wave Length ◽  
Cylindrical Symmetry ◽  
Electron Wave ◽  
Third Order ◽  
The Third ◽  
Probe Radius ◽  
Small Probe ◽  
Probe Size

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.

Children’s Recall of Approximations to English

1973 ◽  
Vol 16 (2) ◽  
pp. 201-212 ◽  
Author(s):  
Elizabeth Carrow ◽  
Michael Mauldin
Keyword(s):  
Language Development ◽  
Fourth Order ◽  
Third Order ◽  
Memory Processes ◽  
The Third ◽  
General Index ◽  
General Linguistic

As a general index of language development, the recall of first through fourth order approximations to English was examined in four, five, six, and seven year olds and adults. Data suggested that recall improved with age, and increases in approximation to English were accompanied by increases in recall for six and seven year olds and adults. Recall improved for four and five year olds through the third order but declined at the fourth. The latter finding was attributed to deficits in semantic structures and memory processes in four and five year olds. The former finding was interpreted as an index of the development of general linguistic processes.

Sign in / Sign up

Export Citation Format

Share Document