Studies in Molecular Dynamics by Collision Induced Infrared Absorption in H2–Rare Gas Mixtures. III. H2–He Mixtures at Low Temperatures and Densities

1975 ◽  
Vol 53 (19) ◽  
pp. 2060-2067 ◽  
Author(s):  
A. R. W. McKellar ◽  
J. W. Mactaggart ◽  
H. L. Welsh
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Infrared Absorption ◽  
Interference Effect ◽  
Low Temperatures ◽  
Profile Analysis ◽  
Rare Gas ◽  
Absorption Profile ◽  
Higher Temperature ◽  
Density Results

The collision induced fundamental band of H2 has been studied in H2–He mixtures with absorption paths of 110 and 165 m in a low temperature multiple traversal cell. Spectra were obtained at 18 and 61.5 K with densities in the range of 9 to 60 amagat. Under these conditions the structure of the band is particularly simple and amenable to analysis; the results of a profile analysis of the present spectra are compared with the higher temperature and density results in paper I (Mactaggart and Welsh) of this series. The long observed splitting of the Q branch of the H2 fundamental is manifested here as very sharp dips in the absorption profile at the Q1(0) and Q1(1) molecular frequencies and these provide a striking confirmation of Van Kranendonk's explanation of the 'splitting' as due to an intercollisional interference effect.

On new compounds of carbon and hydrogen, and on certain other products obtained during the decomposition of oil by heat

1833 ◽  
Vol 2 ◽  
pp. 248-249
Keyword(s):  
Low Temperature ◽  
Specific Gravity ◽  
Solid Body ◽  
Low Temperatures ◽  
Transparent Liquid ◽  
Higher Temperature ◽  
New Compounds ◽  
Oil Gas ◽  
Crystalline Mass

The experiments of which the results are detailed in this paper, were made principally on the fluid which is found to be deposited in considerable quantity when oil-gas is compressed. This fluid, as obtained at the works of the Portable Oil-gas Company, is colourless, of a specific gravity less than that of water; insoluble in water except in very minute quantities; soluble in alcohol, ether, oils, &c.; and combustible, burning with a dense flame. It is strikingly distinguished from the oil from which it originated, by not being acted upon to any extent by solutions of the alkalies. Part of this fluid is very volatile, causing the appearance of ebullition at temperatures of 50° or 60°; other parts are more fixed, requiring even 250°, or above, for ebullition. By repeated distillations a series of products were obtained from the most to the least volatile, the most abundant being such as occurred from 170° to 200°. On subjecting these, after numerous rectifications, to a low temperature, it was found that some of them concreted into a crystalline mass, and ultimately a substance was obtained from them, principally by pressure at low temperatures, which upon examination proved to be a new compound of carbon and hydrogen. At common temperatures it appears as a colourless transparent liquid, of specific gravity 0·85, at 60°; having the general odour of oil-gas. Below 42° it is a solid body, forming dendritical transparent crystals, and contracting much during its congelation. At 0° it appears as a white or transparent substance, brittle, pulverulent, and of the hardness nearly of loaf-sugar. It evaporates entirely in the air: when raised to 186° it boils, furnishing a vapour, which has a specific gravity of 40, compared to hydrogen as 1. At a higher temperature the vapour is decomposed, depositing carbon. The substance is combustible, liberating charcoal if oxygen be not abundantly present. Potassium exerts no action upon it below 186°.

The cubic and other structural forms of ice at low temperature and pressure

1957 ◽  
Vol 239 (1216) ◽  
pp. 93-107 ◽  
Keyword(s):  
Electron Diffraction ◽  
Low Temperature ◽  
Heavy Water ◽  
Low Temperatures ◽  
Ordinary Water ◽  
Pattern Characteristic ◽  
Higher Temperature ◽  
Temperature And Pressure ◽  
Diffraction Patterns ◽  
Diamond Type

Deposits have been prepared by injecting water vapour on to a base at low temperatures in an electron-diffraction camera. Three types of diffraction patterns are found, depending on the temperature of the base. Below —140°C diffuse rings are obtained, between —140 and —120°C a sharp ring pattern characteristic of the diamond-type cubic pattern, and above —100°C the normal hexagonal pattern of ice also in the form of sharp rings. Deposits were also formed from the residual vapour in the camera, the method originally used by König. It is found that these deposits evaporate at a much higher temperature than those produced by injection, which suggests that these deposits are associated with some form of contamination. Experiments were also carried out with heavy water. The results are almost identical with those for ordinary water. The same three structural forms are produced under similar conditions, at temperatures which are slightly higher than those for ordinary water.

Studies in Molecular Dynamics by Collision-Induced Infrared Absorption in H2–Rare Gas Mixtures. II. Diffusional Narrowing of Quadrupole-Induced Transitions

1973 ◽  
Vol 51 (18) ◽  
pp. 1971-1977 ◽  
Author(s):  
J. W. Mactaggart ◽  
J. De Remigis ◽  
H. L. Welsh
Keyword(s):  
Molecular Dynamics ◽  
Infrared Absorption ◽  
Diffusion Coefficients ◽  
Reasonable Agreement ◽  
Liquid Mixtures ◽  
Gas Mixtures ◽  
Rare Gas ◽  
Density Region ◽  
Vapor Line ◽  
High Density Region

The profiles of the quadrupole-induced transitions (S1(0), S1(1)) of the pressure-induced fundamental infrared absorption band of hydrogen are studied in H2–Ar, H2–Kr, and H2–Xe gas mixtures up to high densities a few degrees above the critical temperature of the rare gas and in the corresponding liquid mixtures along the liquid–vapor line. The half-width δq of the transitions remains practically constant for the gas mixtures up to densities of several hundred amagat and then decreases rapidly. Values of δq for the liquid mixtures, when corrected for the temperature difference, are the same as the gas values at the same density. The narrowing of the transitions in the high-density region is interpreted in terms of the diffusional narrowing theory of Zaidi and Van Kranendonk, and is used to calculate diffusion coefficients D12 of H2 molecules in dense rare gas fluids. The results are in reasonable agreement with values of D12 previously deduced from the intercollisional interference effect in the overlap-induced components (Q1(0), Q1(1)) of the same band.

scholarly journals Forcing Temperature Affects Postproduction Quality, Dark Respiration Rate, and Ethylene Responsiveness of Pelargonium × domesticum

1992 ◽  
Vol 117 (4) ◽  
pp. 596-599 ◽  
Author(s):  
Kathleen B. Evensen ◽  
Karen M. Olson
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Dark Respiration ◽  
Floral Display ◽  
Dark Respiration Rate ◽  
Respiration Rates ◽  
Carbohydrate Depletion ◽  
Higher Temperature ◽  
High And Low Temperatures ◽  
Reduced Rate

Postproduction quality, net C exchange, and petal abscission in response to ethylene were compared following forcing at 21(day)/16C(night) or 18/13C(18-hour photoperiod) of two cultivars of Pelargonium × domesticum L.H. Bailey. Fewer petals of 2- to 6-day-old florets abscised in response to 60 minutes of 0.7 μl ethylene/liter on plants forced at low temperature than on plants forced at 3C higher temperature. Forcing temperature did not affect floret longevity or the number of florets opening during forcing, but the floral display under simulated consumer conditions was prolonged in low-temperature plants by the continued development of buds. Dark respiration rates at 21C were lower in leaves from plants forced at low temperature than in leaves of plants forced at the higher temperature. Differences in postproduction quality between plants forced at high and low temperatures may have been related to the reduced rate of carbohydrate depletion in low-temperature plants.

scholarly journals The low temperature D+ + H2 → HD + H+ reaction rate coefficient: a ring polymer molecular dynamics and quasi-classical trajectory study

2018 ◽  
Vol 20 (41) ◽  
pp. 26752-26763 ◽  
Author(s):  
Somnath Bhowmick ◽  
Duncan Bossion ◽  
Yohann Scribano ◽  
Yury V. Suleimanov
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Low Temperatures ◽  
Reaction Rate ◽  
Rate Coefficient ◽  
Classical Trajectory ◽  
Reaction Rate Coefficient ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Trajectory Methods

The D+ + H2 → HD + H+ reaction rate coefficient has been calculated at low temperatures (20–100 K) by ring polymer molecular dynamics and quasi-classical trajectory methods.

PRESSURE-INDUCED INFRARED ABSORPTION OF GASEOUS HYDROGEN AND DEUTERIUM AT LOW TEMPERATURES: I. THE INTEGRATED ABSORPTION COEFFICIENTS

1965 ◽  
Vol 43 (5) ◽  
pp. 818-828 ◽  
Author(s):  
A. Watanabe ◽  
H. L. Welsh
Keyword(s):  
Fine Structure ◽  
Low Temperature ◽  
Infrared Absorption ◽  
Low Temperatures ◽  
Bound States ◽  
Gaseous Hydrogen ◽  
Absorption Coefficients ◽  
Spectroscopic Evidence ◽  
Mixture Formula ◽  
Path Lengths

The pressure-induced infrared absorption of the fundamental band of hydrogen, in the pure gas and in a H2–He mixture, and of deuterium was studied in the temperature range from 18 °K to 77 °K. Path lengths up to 13.6 m at 1 atm or somewhat higher were obtained in a multiple-traversal cell cooled by liquid hydrogen or nitrogen. The binary coefficient [Formula: see text] for hydrogen shows a rise at low temperature, indicating the existence of bound states predicted by theory for the (H2)2 complex. The effect is more pronounced for deuterium. For the H2–He mixture [Formula: see text] decreases monotonically with temperature, thus showing no evidence of bound states for H2–He pairs. Fine structure at the maxima of the pressure-induced band in hydrogen and deuterium gives direct spectroscopic evidence of bound states of (H2)2 and (D2)2 complexes at low temperatures.

Theoretical study of the ν3 and ν4 Raman bands of methane in rare gas matrices

1976 ◽  
Vol 54 (13) ◽  
pp. 2154-2161 ◽  
Author(s):  
Koji Kobashi ◽  
Yosuke Kataoka ◽  
Tsunenobu Yamamoto
Keyword(s):  
Raman Scattering ◽  
Raman Spectra ◽  
Infrared Spectra ◽  
Infrared Absorption ◽  
Low Temperatures ◽  
Theoretical Study ◽  
Mutual Exclusion ◽  
Theoretical Work ◽  
Rare Gas ◽  
Vibration Rotation

Theoretical study has been carried out on the Raman spectra of the ν3 and ν4 vibration bands of methane in Ar, Kr, and Xe matrices at low temperatures. The present study is a continuation of a theoretical work by Nishiyama and Yamamoto on the infrared spectra of the same Systems. We consider the symmetry of the System under the group [Formula: see text] introducing the inversion functions to generalize Wigner's rotational functions. As a result, dual assignments are given to each vibration–rotation state. The allowed transitions of the Raman scattering are compared with those of the infrared absorption, and it is found that a kind of 'rule of mutual exclusion' holds. The relative intensities and spacings of the Raman spectra are calculated and successfully compared with experiment.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

INVAR M93

Alloy Digest ◽  
2008 ◽  
Vol 57 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Ni Content ◽  
Precision Alloys ◽  
Ni Alloy

Abstract Invar is an Fe-Ni alloy with 36% Ni content that exhibits the lowest expansion of known metals from very low temperatures up to approximately 230 deg C (445 deg F). Invar M93 is a cryogenic Invar with improved weldability. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear and bend strength as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as forming and joining. Filing Code: FE-143. Producer or source: Metalimphy Precision Alloys.

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