THEORY OF THE PRESSURE-INDUCED ROTATIONAL SPECTRUM OF HYDROGEN

1959 ◽  
Vol 37 (10) ◽  
pp. 1187-1198 ◽  
Author(s):  
J. Van Kranendonk ◽  
Z. J. Kiss
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Absorption Coefficient ◽  
Pair Distribution Function ◽  
Wave Functions ◽  
Rotational Line ◽  
Induction Effect ◽  
Rotational Spectrum ◽  
Absorption Coefficients ◽  
Good Agreement

The theory of induced infrared absorption developed previously is applied to the pressure-induced rotational spectrum of hydrogen. The intensity of the rotational band is due mainly to the quadrupolar induction effect, and to a small interference effect between the quadrupolar and overlap moments. From the experimental data on the binary absorption coefficients, values of the angle-dependent overlap moments are obtained for H2–He, H2–H2, H2–Ne, H2–N2, and H2–A. A calculation of the overlap moment for pure H2 is presented. Rosen-type wave functions appear to be inadequate for a calculation of the small angle-dependent rotational as well as vibrational overlap moments. The temperature dependence of the binary absorption coefficient is calculated, taking into account the quantum effects in the pair distribution function, and found to be in good agreement with the experimental data. The dependence on the ortho–para ratio is also discussed. The double rotational line S(1) + S(1) has been observed and its intensity measured.

THE THEORY OF COLLISION-INDUCED ABSORPTION IN HYDROGEN AND DEUTERIUM

1958 ◽  
Vol 36 (6) ◽  
pp. 761-783 ◽  
Author(s):  
F. R. Britton ◽  
M. F. Crawford
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Quadrupole Moments ◽  
Absorption Coefficients ◽  
Induced Dipole ◽  
Binary Collisions ◽  
Experimental Values ◽  
Indirect Part ◽  
Experimental Ratio ◽  
Good Agreement

Collision-induced absorptions in the 1–0 vibrational band of hydrogen and of deuterium are calculated by considering interactions during binary collisions. The induced dipole moment, μ, of an interacting molecule-pair is derived by combining a moment, μa, resulting from overlap forces, with a moment, μq, due to the interactions of permanent molecular quadrupole moments. μa consists of two additive parts, an indirect part calculated by van Kranendonk and Bird (1951) and a direct part calculated in this paper. μq is calculated in two different ways: (a) theoretically and (b) semiempirically. Absorption coefficients are evaluated for temperatures 296 ° K. and 80 ° K. For H2 at 296 ° K. the total integrated coefficient obtained by using procedure (a) is 8.6% smaller and by using (b) is 8.2% larger than the experimental value. The experimental ratio of the coefficients of the Q and S branches is in much better agreement with (b) than (a). For T = 80 °K. the experimental value of the total integrated coefficient is only 61% of that calculated by (b). The good agreement between calculated and experimental values of absorption coefficients at room temperature suggests that at low temperatures the classical distribution function used in this paper must be replaced by the quantal pair distribution function. Experimental data for D2 are not available.

Inelastic electric and magnetic electron scattering form factors of 24Mg nucleus: Role of g factors

2017 ◽  
Vol 26 (05) ◽  
pp. 1750032 ◽  
Author(s):  
Anwer A. Al-Sammarraie ◽  
M. L. Inche Ibrahim ◽  
Muna Ahmed Saeed ◽  
Fadhil I. Sharrad ◽  
Hasan Abu Kassim
Keyword(s):  
Experimental Data ◽  
Electron Scattering ◽  
Form Factors ◽  
Wave Functions ◽  
Matrix Elements ◽  
Model Hamiltonian ◽  
Transverse Electron ◽  
Magnetic Electron ◽  
Good Agreement

The electric and magnetic transitions in the [Formula: see text]Mg nucleus are studied based on the calculations of the longitudinal and the transverse electron scattering form factors. The universal sd-shell model Hamiltonian (USDA) is used for calculations. The wave functions of radial single-particle matrix elements are calculated using the Skyrme potential. For the longitudinal form factors, a good agreement is obtained between the calculations and the experimental data. For the transverse form factors, the effective [Formula: see text] factors are made as adjustable parameters in order to describe the experimental data.

Sound absorption of textile curtains – theoretical models and validations by experiments and simulations

2016 ◽  
Vol 88 (1) ◽  
pp. 36-48 ◽  
Author(s):  
Reto Pieren ◽  
Beat Schäffer ◽  
Stefan Schoenwald ◽  
Kurt Eggenschwiler
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Planning Process ◽  
Measurement Data ◽  
Theoretical Models ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Semi Empirical ◽  
Field Sound ◽  
Good Agreement

Textile curtains can be designed to be good sound absorbers. Their acoustical performance, as usually described by the sound absorption coefficient, not only depends on the textile itself but also on the drapery fullness and the backing condition, that is, the spacing between the fabric and a rigid backing wall, or the absence of a backing in the case of a freely hanging curtain. This article reviews existing models to predict the diffuse-field sound absorption coefficient, which to date can only predict the case of flat curtains. A set of existing models is extended to the case of curtains with drapery fullness using a semi-empirical approach. The models consider different backing conditions, including freely hanging curtains. The existing and new models are validated by comparing predicted sound absorption coefficients with data measured in a reverberation room. Hereby, curtains consisting of different fabrics and with different degrees of fullness are considered. Besides situations with rigid backing, also the measurement data of textiles hung freely in space are included in this study. Comparisons reveal a very good agreement between measured and predicted sound absorption coefficients. Compared to currently available commercial sound absorption prediction software that can only handle the situation of flat textiles with rigid backing, the results of the presented models not only show a better agreement with measured data, but also cover a broader range of situations. The presented models are thus well applicable in the design and development of new textiles as well as in the room acoustical planning process.

Sound absorption characterization of aluminum foam made by press infiltration casting

2016 ◽  
Vol 12 (4) ◽  
pp. 737-747 ◽  
Author(s):  
J.X. Sun ◽  
C.Y. Duan ◽  
P.S. Liu
Keyword(s):  
Experimental Data ◽  
Absorption Coefficient ◽  
Sound Wave ◽  
Sound Absorption ◽  
Aluminum Foam ◽  
Peak Frequency ◽  
Experimental Result ◽  
Content Type ◽  
Improved Model ◽  
Good Agreement

Purpose The purpose of this paper is to investigate the sound absorption by modeling for the aluminum foam produced by press infiltration casting. Design/methodology/approach First use Johnson-Allard-Champoux (JAC) model to calculate the sound absorption coefficient of the present aluminum foam, and then improve it after finding its deviation from the experimental data, so as to get an improved model that could have a good agreement with the experimental result. Findings Using JAC model to calculate the sound absorption coefficient of the present aluminum foam, it is found that the model may have a good agreement with the experimental data only for the sound wave frequency below the absorption peak frequency, but a large deviation from the experimental result for the sound wave frequency above this frequency. Originality/value Improving JAC model by means of two factors, i.e., the absorption peak frequency and the specific surface area, the resultant improved model could be in good agreement with the experimental data.

scholarly journals ENERGY AND STRUCTURE STATES OF LOW-LYING BANDS IN 156Gd

2021 ◽  
Vol 22 (1) ◽  
pp. 167-174
Author(s):  
P.N. Usmanov ◽  
E.K. Yusupov
Keyword(s):  
Experimental Data ◽  
Phenomenological Model ◽  
Wave Functions ◽  
Experimental Results ◽  
Rotational Bands ◽  
Calculated Energy ◽  
Inertial Parameters ◽  
Good Agreement

The experimental results of the literary and electronic nuclear database for 156Gd were summarized and analyzed. Inertial parameters of rotating core were determined using the Harris method. The theoretical values of energy and wave functions were calculated within the framework of a phenomenological model that takes into account Coriolis mixing of state rotational bands. The calculated energy values were compared with existing experimental data, which were in good agreement. ABSTRAK: Hasil dapatan kajian melalui eksperimen pangkalan data nuklear dan elektronik bagi 156Gd diringkaskan dan dianalisis. Parameter inersia putaran berputar ditentukan menggunakan kaedah Harris. Nilai teori fungsi tenaga dan gelombang dikira dalam kerangka model fenomenologi yang mengambil kira campuran Coriolis pada band putaran keadaan. Nilai pengiraan tenaga dibandingkan dengan data eksperimen memberikan persetujuan yang baik.

THE ABSORPTION OF GAMMA-RAYS FROM Co60

1947 ◽  
Vol 25a (6) ◽  
pp. 303-314 ◽  
Author(s):  
W. V. Mayneord ◽  
A. J. Cipriani
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Gamma Rays ◽  
Heavy Elements ◽  
Photoelectric Absorption ◽  
Lead Absorber ◽  
Absorption Coefficients ◽  
Cobalt Radiation ◽  
Good Agreement ◽  
Made In

Measurements of the absorption of gamma-rays from Co60 and radium have been made in a number of materials. Variation of absorption coefficient of the gamma-rays from radium with thickness of lead absorber is in agreement with recent experimental determinations. The gamma-rays from Co60 are approximately monochromatic and are therefore suitable for testing theoretical absorption formulae. The absorption coefficient per electron for materials of atomic number equal to or less than that of aluminium was in agreement with the Klein–Nishina formula, assuming the cobalt radiation to consist of two lines at 1.10 and 1.30 Mev. respectively. The photoelectric absorption coefficients per electron for heavy elements are in good agreement with the theory developed by Hulme, McDougall, Buckingham, and Fowler. This coefficient varies approximately as Z3.5.

Détermination du coefficient d'absorption des rayons X à partir des mesures de réflectométrie X

2004 ◽  
Vol 82 (1) ◽  
pp. 75-79 ◽  
Author(s):  
E Ech-chamikh ◽  
I Aboudihab ◽  
M Azizan ◽  
A Essafti ◽  
Y Ijdiyaou
Keyword(s):  
Absorption Coefficient ◽  
Amorphous Carbon ◽  
X Rays ◽  
Absorption Coefficients ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Simple Method ◽  
Material Layer ◽  
Reflectivity Spectra ◽  
Good Agreement

In this paper, we present a simple method that allows, among other things, to determine the absorption coefficient of X-rays from reflectivity measurements. This method is applicable if the analysed material is deposited on a substrate denser than the material layer, so that the X-rays reflectivity spectra exhibit two well-resolved descents. In such cases, the amplitude of the first descent (characteristic of the material layer) is directly related to the linear absorption coefficient of the material constituting the layer. We have been able to clarify this relationship and apply it successfully for several cases of materials, especially amorphous carbon and silicon. Values of thus obtained mass absorption coefficients are in very good agreement with those tabulated in the literature.[Journal translation]

scholarly journals Оптические свойства спироида C-=SUB=-300-=/SUB=-

2019 ◽  
Vol 89 (2) ◽  
pp. 169
Author(s):  
С.Г. Ястребов ◽  
М.С. Чекулаев ◽  
A. Siklitskaya
Keyword(s):  
Experimental Data ◽  
Matrix Element ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Exchange Interaction ◽  
Optical Absorption Coefficient ◽  
Local Curvature ◽  
The Matrix ◽  
Strong Coupling Method ◽  
Good Agreement

AbstractCalculation results of the electronic spectrum of carbon nanospiroid C_300 are presented. The π-electron structure of the spiroid is calculated using the strong coupling method, in which the matrix element of the exchange interaction of neighboring electrons (the resonance integral) is considered as being dependent on the local curvature of the spiroid surface. The optical absorption coefficient is calculated in the framework of the Tautz model and the result is compared with experimental and astrophysical observational data. The calculated and experimental data are in good agreement.

A variational method for the ground state of a Bose fluid

1960 ◽  
Vol 256 (1284) ◽  
pp. 106-114 ◽  
Keyword(s):  
Integral Equation ◽  
Wave Function ◽  
Distribution Function ◽  
Variational Principle ◽  
Variational Method ◽  
Ground State ◽  
Pair Distribution Function ◽  
Wave Functions ◽  
Absolute Zero ◽  
Superposition Approximation

A modification of the Rayleigh—Ritz variational principle is described which makes possible a calculation of the energy, wave function, and pair distribution function f 12 ≡ f ( x 1 , x 2 ) of a Bose fluid, such as liquid 4 He, at absolute zero. The assumptions made are: (i) two-body interactions with potential U ij , (ii) trial wave functions of the form f 12 ≡ f ( x 1 , x 2 ) and (iii) the Kirkwood ‘superposition' approximation. Under these approximations, the expectation energy is E = 1 2 n 2 ∫ ∫ d 3 X 1 d 3 X 2 f 12 U 12 − h 2 m − 1 ( ∇ 1 8 ϕ 12 ) + ( ∇ 1 ϕ 12 ) 2 + n ∫ d 3 X 2 f 13 f 23 ϕ 12 ⋅ ∇ 1 ϕ 13 , where n ≡ N/V . It is shown here that making E stationary with respect to independent variations in f and ɸ corresponds to simultaneously applying the ordinary Rayleigh-Ritz principle and solving the Born-Green-Yvon integral equation for f . The method is illustrated by reproducing Bogolyubov’s results for the case where U is small. The case where U is large must be dealt with numerically, but transformations for simplifying the computations are given here.

The Acoustic Properties of Expanded Clay Granulates

2002 ◽  
Vol 9 (2) ◽  
pp. 85-98 ◽  
Author(s):  
F. Asdrubali ◽  
K. V. Horoshenkov
Keyword(s):  
Experimental Data ◽  
Absorption Coefficient ◽  
Acoustic Impedance ◽  
Acoustic Properties ◽  
Low Density ◽  
Frequency Range ◽  
Approximation Approach ◽  
Acoustic Performance ◽  
Granular Base ◽  
Good Agreement

The purpose of this work is to characterise experimentally and theoretically the acoustic performance of mixes of loose expanded clay granulates. The surface acoustic impedance is obtained from measurements in the impedance tube and predicted using the Pade approximation approach. The random incidence absorption coefficient is measured using the ISO 345/85 method. Experimental data for the surface acoustic impedance are used to deduce the porosity, tortuosity and the statistical pore size distribution; these parameters are difficult to obtain directly, because of the relatively low density of the loose granulates and the fact that the granular base contains 5–30% of the closed, unconnected pores. Good agreement between the theory and the results is found; 50–100 mm layers of expanded clay granulates can be used efficiently for noise control over a broad frequency range.

Sign in / Sign up

Export Citation Format

Share Document