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.

Pressure-Induced Infrared Absorption of Gaseous Hydrogen and Deuterium at Low Temperatures. III. Further Analysis of the Fundamental and First Overtone Bands of Hydrogen

1971 ◽  
Vol 49 (10) ◽  
pp. 1320-1326 ◽  
Author(s):  
A. Watanabe
Keyword(s):  
Density Dependence ◽  
Quadrupole Moment ◽  
Infrared Spectra ◽  
Infrared Absorption ◽  
Low Temperatures ◽  
Gaseous Hydrogen ◽  
Matrix Elements ◽  
Satisfactory Explanation ◽  
Satisfactory Degree ◽  
Double Transition

Pressure-induced infrared spectra of hydrogen in the fundamental region, recorded at 18, 20.4, and 24 K, have been reanalyzed making use of recently calculated theoretical matrix elements of the polarizability and the quadrupole moment of hydrogen. The analysis revealed a density dependence in the relative intensities of the single and double transition quadrupolar induced components. This density dependence was used as a correction to improve the analysis of the first overtone spectrum, obtained at 24 K with a density of 31 amagat. The observed and calculated spectra then agreed to a satisfactory degree except for a discrepancy in the intensity of the Q1(1) + Q1(J) components for which no satisfactory explanation could be given.

The specific heat of carbon dioxide and the form of the CO2 molecule

1927 ◽  
Vol 23 (8) ◽  
pp. 890-900 ◽  
Author(s):  
W. H. McCrea
Keyword(s):  
Carbon Dioxide ◽  
Fine Structure ◽  
High Temperature ◽  
Low Temperature ◽  
Specific Heat ◽  
Low Temperatures ◽  
Molecular Model ◽  
Band Spectrum ◽  
Spectrum Data

SummaryTwo alternative forms of the CO2 molecule have been suggested by various authors who have discussed the band spectrum data. The specific heat curves based on these models are considered here. It is found that neither is quite satisfactory over the whole range of temperature and we discuss the difficulties for the low temperature and high temperature portions separately. In order to get agreement for low temperatures we find it necessary to introduce a further hypothesis about the molecular model which also seems to explain one or two outstanding difficulties in interpreting the fine structure of the bands. This assumption does not make any difference at higher temperatures where we show the error in one of the curves to be of the order we should expect to be accounted for by a centrifugal stretching of the molecule.

Spectra in the O-H stretching region of mono- and oligo-saccharides at low temperatures

1968 ◽  
Vol 21 (5) ◽  
pp. 1257 ◽  
Author(s):  
AJ Michell
Keyword(s):  
Fine Structure ◽  
Low Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Coupled Vibrations ◽  
Temperature Spectra

Spectra in the O-H stretching region of some mono- and oligosaccharides have been obtained at low temperatures. Bands in the low-temperature spectra were found to be sharper and better resolved, and some bands were revealed which were not apparent at room temperature. Spectra have also been obtained in both the O-H and O-D stretching regions of partly deuterated samples of two glycosides and an oligosaccharide. From these it has been shown that the fine structure in the O-H stretching region of the spectra of these compounds arises from coupled vibrations rather than from separate vibrations of individual groups. This coupling is probably the underlying reason for the large widths of bands in this region of the spectrum of carbohydrates.

PRESSURE-INDUCED INFRARED ABSORPTION OF GASEOUS HYDROGEN AND DEUTERIUM AT LOW TEMPERATURES: II. ANALYSIS OF THE BAND PROFILES FOR HYDROGEN

1967 ◽  
Vol 45 (9) ◽  
pp. 2859-2871 ◽  
Author(s):  
A. Watanabe ◽  
H. L. Welsh
Keyword(s):  
Infrared Absorption ◽  
Low Temperatures ◽  
Theoretical Calculations ◽  
Computational Procedure ◽  
Gaseous Hydrogen ◽  
Infrared Band ◽  
Line Form ◽  
Dispersion Line ◽  
Good Agreement

Experimental profiles for the pressure-induced fundamental infrared band of hydrogen for a number of temperatures in the range 18–77 °K were analyzed by a computational procedure. Half-widths and peak intensities of 11 components, assumed to have a Boltzmann-modified dispersion line form, were obtained from the analysis. The contributions of the quadrupolar and overlap interactions to the total intensity, as well as their variation with temperature, showed good agreement with theoretical calculations on the exp–4 model.

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.

INFRARED ABSORPTION OF FORMALDEHYDE AT LOW TEMPERATURES: EVIDENCE FOR MULTIPLE TRAPPING SITES IN AN ARGON MATRIX

1962 ◽  
Vol 40 (1) ◽  
pp. 85-91 ◽  
Author(s):  
K. B. Harvey ◽  
J. F. Ogilvie
Keyword(s):  
Fine Structure ◽  
Infrared Absorption ◽  
Low Temperatures ◽  
Point Of View ◽  
Monomeric Form ◽  
Argon Matrix ◽  
Inert Matrix ◽  
Multiple Trapping ◽  
The Matrix ◽  
Trapping Sites

The infrared absorption of formaldehyde in both the polycrystalline and the monomeric form has been measured at 4 °K. In the latter case the molecules were suspended in an inert matrix of Ar or N2. The fine structure of the matrix spectra is discussed from the point of view of rotation of the monomers but this interpretation is ruled out in favor of one based on multiple trapping sites in the matrix.

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.

Ultrastructure of the soil fungus, Geomyces pannorus

1984 ◽  
Vol 42 ◽  
pp. 738-739
Author(s):  
J. A. Traquair ◽  
E. G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fine Structure ◽  
Low Temperatures ◽  
Soil Fungus ◽  
Organic Soils ◽  
Anatomical Studies ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Scanning Electron

With the advent of improved dehydration techniques, scanning electron microscopy has become routine in anatomical studies of fungi. Fine structure of hyphae and spore surfaces has been illustrated for many hyphomycetes, and yet, the ultrastructure of the ubiquitous soil fungus, Geomyces pannorus (Link) Sigler & Carmichael has been neglected. This presentation shows that scanning and transmission electron microscopical data must be correlated in resolving septal structure and conidial release in G. pannorus.Although it is reported to be cellulolytic but not keratinolytic, G. pannorus is found on human skin, animals, birds, mushrooms, dung, roots, and frozen meat in addition to various organic soils. In fact, it readily adapts to growth at low temperatures.

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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