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.

ANALYSIS OF THE PROFILE OF THE FUNDAMENTAL INFRARED BAND OF HYDROGEN IN PRESSURE-INDUCED ABSORPTION

1964 ◽  
Vol 42 (5) ◽  
pp. 873-885 ◽  
Author(s):  
J. L. Hunt ◽  
H. L. Welsh
Keyword(s):  
Absorption Band ◽  
Infrared Absorption ◽  
Line Shape ◽  
Computational Procedure ◽  
Pure Hydrogen ◽  
Square Root ◽  
Infrared Band ◽  
Integrated Intensities ◽  
Boltzmann Law ◽  
Dispersion Line

The pressure-induced fundamental infrared absorption band of hydrogen was measured for a series of pressures in the pure gas and in a H2–He mixture at 300 °K, 195 °K, and 78 °K, and in H2–A and H2–N2 mixtures at 300 °K. The band profiles were separated by a computational procedure into QP and QR (overlap) components and QQ and S(J) (quadrupole) components using a dispersion line shape modified by the Boltzmann law. The dispersion half-width obtained for the overlap components was about twice as great as for the quadrupole components; both half-widths varied as the square root of the temperature. The S(J) lines in pure hydrogen consisted of single and double transitions, the relative intensities of which were in accordance with the assumption of quadrupole interaction. Ortho–para ratios of 3:1 and 1:1 were used in the experiments; the integrated intensities of the band showed very little dependence on the ortho–para ratio, in disagreement with a previously reported result.

Two types of localized excess electrons in crystalline D2O ice

1977 ◽  
Vol 55 (12) ◽  
pp. 2385-2395 ◽  
Author(s):  
George V. Buxton ◽  
Hugh A. Gillis ◽  
Norman V. Klassen
Keyword(s):  
Absorption Band ◽  
Infrared Absorption ◽  
Low Temperatures ◽  
Total Yield ◽  
Equilibrium Concentration ◽  
Electron Trap ◽  
Decay Kinetics ◽  
Infrared Band ◽  
Visible Absorption ◽  
Perfect Lattice

In a pulse radiolysis study of crystalline D2O ice, an intense infrared absorption band with λmax > 2350 nm has been found at low temperatures, in addition to the well-known visible absorption band of the trapped electron. The infrared band is also attributed to trapped electrons, partly because of its similarity to the electron absorption band found recently in some D2O glasses at low temperatures. The effects of temperature, dose per pulse, accumulated dose, and added NH4F, HF, and ND3 on the yields and decay kinetics of both bands have been investigated. It is concluded that the electron trap giving rise to the visible band is a vacancy which at low temperatures is radiation-produced by a two-step spur process. At temperatures close to the melting point the vacancy-trap probably exists before the radiation pulse at equilibrium concentration. The electron trap which gives rise to the infrared band is thought to be a cavity that occurs naturally in the perfect lattice. For previously unirradiated samples the infrared band decays by a second order process which is remarkably fast [Formula: see text] The decay reaction is probably neutralization by D2O+. Doping with NH4F increases the yield of the infrared absorption and greatly decreases its decay rate. The total yield of localized electrons in irradiated crystalline D2O is higher than has been generally recognized.

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.

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 and experimental research on slip and uplift of the timber-concrete composite beam

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 7079-7099
Author(s):  
Jianying Chen ◽  
Guojing He ◽  
Xiaodong (Alice) Wang ◽  
Jiejun Wang ◽  
Jin Yi ◽  
...  
Keyword(s):  
Differential Equations ◽  
Deformation Theory ◽  
Concrete Slab ◽  
Theoretical Calculations ◽  
Structural Element ◽  
Structural Efficiency ◽  
Theoretical Investigations ◽  
New Type ◽  
Interlayer Slip ◽  
Good Agreement

Timber-concrete composite beams are a new type of structural element that is environmentally friendly. The structural efficiency of this kind of beam highly depends on the stiffness of the interlayer connection. The structural efficiency of the composite was evaluated by experimental and theoretical investigations performed on the relative horizontal slip and vertical uplift along the interlayer between composite’s timber and concrete slab. Differential equations were established based on a theoretical analysis of combination effects of interlayer slip and vertical uplift, by using deformation theory of elastics. Subsequently, the differential equations were solved and the magnitude of uplift force at the interlayer was obtained. It was concluded that the theoretical calculations were in good agreement with the results of experimentation.

scholarly journals Etude par résonance magnétique nucléaire de composés organiques contenant des chalcogènes. II. L'éther de diphényle et ses analogues soufré, sélénié et telluré

1979 ◽  
Vol 57 (22) ◽  
pp. 2967-2970 ◽  
Author(s):  
Gabriel Llabrès ◽  
Marcel Baiwir ◽  
Léon Christiaens ◽  
Jean-Louis Piette
Keyword(s):  
Crystal Structure ◽  
Theoretical Calculations ◽  
Heavy Atom ◽  
Mesomeric Effect ◽  
Heavy Atom Effect ◽  
Inductive Effects ◽  
Structure Determinations ◽  
Résonance Magnétique ◽  
Atom Effect ◽  
Good Agreement

The 1Hmr study of the title compounds has revealed a screw conformation, with defined interconversion processes, in good agreement with crystal structure determinations and theoretical calculations. The mesomeric effect of the heteroatom is smaller than in the anisole series, due to steric inhibitions.The 13Cmr enhances, to some extent, these conclusions. In the case of Te compounds, a heavy atom effect adds to the classical mesomeric and inductive effects to account for the experimental observations.

scholarly journals Atmospheric Lifetimes, Infrared Absorption Spectra, Radiative Forcings and Global Warming Potentials of NF<sub>3</sub> and CFC-115

2016 ◽  
Author(s):  
Anna Totterdill ◽  
Tamás Kovács ◽  
Wuhu Feng ◽  
Sandip Dhomse ◽  
Christopher J. Smith ◽  
...  
Keyword(s):  
Global Warming ◽  
Cross Sections ◽  
Infrared Absorption ◽  
Radiative Forcing ◽  
Climate Model ◽  
Radiative Forcings ◽  
Atmospheric Window ◽  
Infrared Absorption Spectra ◽  
Global Warming Potentials ◽  
Good Agreement

Abstract. Fluorinated compounds such as NF3 and C2F5Cl (CFC-115) are characterised by very large global warming potentials (GWPs) which result from extremely long atmospheric lifetimes and strong infrared absorptions in the atmospheric window. In this study we have experimentally determined the infrared absorption cross-sections of NF3 and CFC-115, calculated the radiative forcing and efficiency using two radiative transfer models and identified the effect of clouds and stratospheric adjustment. The infrared cross sections are in good agreement with previous measurements, whereas the resulting radiative forcings and efficiencies are, on average, around 10 % larger. A whole atmosphere chemistry-climate model was used to determine the atmospheric lifetimes of NF3 and CFC-115 to be (616 ± 34) years and (492 ± 22) years, respectively. The GWPs for NF3 are estimated to be 14 600, 19 400 and 21 400 over 20, 100 and 500 years, respectively. Similarly, the GWPs for CFC-115 are 6120, 8060 and 8630 over 20, 100 and 500 years, respectively.

The continuous absorption of light in alkali-metal vapours

1953 ◽  
Vol 219 (1136) ◽  
pp. 89-101 ◽  
Keyword(s):  
Cross Section ◽  
Alkali Metals ◽  
Theoretical Calculations ◽  
Wave Length ◽  
Energy Difference ◽  
Continuous Absorption ◽  
Absorption Of Light ◽  
Sodium Vapour ◽  
Good Agreement ◽  
Dipole Length

The first section of this paper is an account of some experiments on the absorption of light in sodium vapour from the series limit at 2412 Å to about 1600 Å (an energy difference of 2·6 eV). The absorption cross-section at the limit is 11·6 ± 1·2 x 10 -20 cm 2 . The cross-section decreases giving a minimum of 1·3 ± 0·6 x 10 -20 cm 2 at 1900 Å and then increases to 1600 Å. A theoretical calculation by Seaton based on the dipole-length formula gives good agreement with the experiments at the series limit and also correctly predicts the wave-length for the minimum, but it predicts a significantly lower absorption at the minimum. The experiments described in the first section of the paper conclude a series on the absorption of light in the alkali metals. The second section consists of a general discussion of the results of these experiments and of their relation to theoretical calculations. There is good agreement between theory and experiment except in regard to the magnitude of the absorption at the minimum.

Isotopic Thermal Diffusion Factors for Helium and Neon at Low Temperatures

1963 ◽  
Vol 18 (2) ◽  
pp. 242-245 ◽  
Author(s):  
W. W. Watson ◽  
A. J. Howard ◽  
N. E. Miller ◽  
R. M. Shiffrin
Keyword(s):  
Thermal Diffusion ◽  
Low Temperatures ◽  
Quantum Corrections ◽  
Intermolecular Potential ◽  
De Vries ◽  
Lower Temperature ◽  
Improved Accuracy ◽  
Good Agreement

With an all-metal “swing separator” having unique features, thermal diffusion factors αT for He3/He4 and Ne20Ne22 have been measured with improved accuracy down to average gas temperatures T̅=136°K. For helium αT is 0.0696 ± 0.0010 at 136°K, dropping gradually to 0.0651 ±0.0010 at 313°K. These data, plus measurements by Van der Valk and de Vries at somewhat higher temperatures, agree best with values predicted by an exp-six intermolecular potential with ε/k=9.16 and α=12.7. We are extending these helium measurements down to T=4°K for the lower temperature, to detect if possible quantum corrections to the intermolecular potential. For neon αT increases from 0.0166 ± 0.0010 at 136°K to 0.0233 ± 0.0020 at 310°K, considerably higher than our previously reported values. These T. D. factors for neon are in good agreement with values calculated from an exp-six potential with ε/k = 46.0 ± 0.6 and α=13.

scholarly journals Influence of Frequency on the Resolution of Magnetostrictive Bio-Inspired Whisker Sensors

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Ran Zhao ◽  
Bo-wen Wang ◽  
Quan-guo Lu ◽  
Jian-wu Yan ◽  
Xiao-cui Yuan
Keyword(s):  
Vibration Frequency ◽  
Dynamic Testing ◽  
Theoretical Calculations ◽  
Beam Theory ◽  
Experimental System ◽  
Flow Sensors ◽  
Maximum Resolution ◽  
Sensing Model ◽  
Euler Bernoulli Beam ◽  
Good Agreement

Magnetostrictive biomimetic whiskers have been used as tactile and flow sensors. Compared to other types of whiskers, such whiskers have the advantage of being able to perform static and dynamic measurements. For dynamic measurement, the whisker’s resolution changes with varying vibration frequency; however, the mechanism for this influence has not been studied yet. Thus, the aim of this study is to investigate the resolution–frequency correlation. First, the structure and operation principle of the whisker were analyzed. Then, the Euler–Bernoulli beam theory was employed to establish the sensing model of the magnetostrictive whisker. Finally, the mapping relationship between sensor resolution and frequency was obtained. The eigenfrequency analysis was implemented by FEM to obtain the frequency response of the whisker. A vibration experimental system was built for dynamic testing. The experimental results were in good agreement with the theoretical calculations. Furthermore, it was noted that the resolution was positively correlated with frequency, and the maximum resolution was attained at the natural frequency (two peak values appeared at the first-order and second-order eigenfrequencies). Our research reveals the manner in which a whisker sensor’s resolution is affected by the vibration frequency. The theoretical model can be used to predict the resolution of magnetostrictive whisker sensors.

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