Neutron scattering and proton spin conversion in solid CH4

1977 ◽  
Vol 55 (18) ◽  
pp. 1580-1588 ◽  
Author(s):  
K. J. Lushington ◽  
J. A. Morrison
Keyword(s):  
Cross Section ◽  
Solid Phase ◽  
Wave Length ◽  
Neutron Cross Section ◽  
Spin Symmetry ◽  
Proton Spin ◽  
Spin Conversion ◽  
Temperature Dependences ◽  
Symmetry Species ◽  
The Mean

The total neutron cross section of pure and O2-doped condensed CH4 has been measured in the temperature range 0.75 < T < 100 K. The neutron wave length was sufficiently long (4.7 Å) so that changes in cross section could be directly related to changes in [Formula: see text], the mean squared proton nuclear angular momentum per molecule, to a sensitivity of about 1%. The temperature dependences of [Formula: see text] for the pure and doped specimens differ considerably in solid phase II (T < 20.4 K). For the former specimen, the change in cross section is consistent with conversion occurring between the nuclear spin symmetry species on the orientationally disordered sublattices only. The addition of oxygen enhances the rate of conversion such that the value of [Formula: see text] corresponds to conversion on both the disordered and ordered sublattices. The characteristic lifetimes of the catalyzed and uncatalyzed conversion processes have been estimated.

Theory of phase transitions in solid methanes. XIV. The total neutron scattering cross section in phase II of solid CH4

1981 ◽  
Vol 59 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Yoshiaki Ozaki ◽  
Yosuke Kataoka ◽  
Kenkichi Okada ◽  
Tsunenobu Yamamoto
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Phase Ii ◽  
Single Molecule ◽  
Neutron Cross Section ◽  
Proton Spin ◽  
Total Neutron ◽  
Rotational States ◽  
Future Experimental Study ◽  
The Mean

The total neutron cross section in phase II of solid CH4 is calculated as a function of the incident energy E0 and the temperature in the ranges [Formula: see text] and [Formula: see text]. The sample is assumed to be a polycrystal and the neutron beam to be unpolarized. The total cross section consists of two parts: proton spin-independent and dependent parts. The latter is given by a sum of σ0 and σ′. Both the spin-independent part and σ0 come from the elastic scattering and can together be cast in the form [Formula: see text] for both Oh andD2d molecules, where [Formula: see text] is the mean squared proton spin angular momentum within a single molecule. The quantity σ′ depends on the details of the spin–rotational states. The calculated total cross section can again be expressed approximately as a linear function of [Formula: see text] as was empirically found by Lushington and Morrison (Can. J. Phys. 55, 1580 (1977)). A prediction is offered for a possible future experimental study.

Short term proton spin conversion in solid CH4

1976 ◽  
Vol 54 (12) ◽  
pp. 1248-1257 ◽  
Author(s):  
R. F. Code ◽  
J. Higinbotham
Keyword(s):  
Magnetic Susceptibility ◽  
Temperature Dependence ◽  
Phase Ii ◽  
Spin Symmetry ◽  
Proton Spin ◽  
Free Rotation ◽  
Short Term ◽  
Spin Conversion ◽  
Low Level ◽  
Thermal Equilibration

Short term measurements were made of the static proton magnetic susceptibility of solid CH4 containing O2 impurities in the temperature range between 1.6 and 80 K. The samples were slowly crystallized and annealed above 80 K. A low level NMR Q-meter detector was used to measure the temperature dependence of the polarization of the hydrogen nuclei in methane relative to the polarization of fluorine nuclei in a thick teflon coil form surrounding the sample after thermal equilibration times of up to 2 h. The results can be consistently interpreted according to the James–Keenan model for Phase II of solid methane by assuming that, during a 2 h period, proton spin symmetry conversion essentially comes to equilibrium on the two disordered sublattices whose molecules are in states of nearly free rotation, but that conversion does not significantly occur within this time for molecules on the six remaining ordered sublattices.

Investigation of the total neutron cross section for natural hafnium on the filtred neutron beam with energy 59 keV

2011 ◽  
Vol 30 (0) ◽  
pp. 142-147
Author(s):  
О. О. Грицай ◽  
А. К. Гримало ◽  
В. В. Колотий ◽  
В. М. Венедиктов ◽  
С. П. Волковецький ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Beam ◽  
Neutron Cross Section ◽  
Total Neutron ◽  
Total Neutron Cross Section

Temperature Dependences in the O + OH → O2 + H Reaction. Quasiclassical Trajectory Calculation

1993 ◽  
Vol 58 (2) ◽  
pp. 234-243 ◽  
Author(s):  
Viliam Klimo ◽  
Martina Bittererová ◽  
Stanislav Biskupič ◽  
Ján Urban ◽  
Miroslav Micov
Keyword(s):  
Temperature Dependence ◽  
Energy Surface ◽  
Analytical Form ◽  
Mean Values ◽  
Quantum Numbers ◽  
Mean Lifetime ◽  
Temperature Dependences ◽  
Quasiclassical Trajectory Calculation ◽  
The Mean ◽  
Combustion Processes

The reaction O + OH → O2 + H in conditions of combustion of hydrocarbons and polymers was modelled by using the method of quasiclassical trajectories. The potential energy surface was determined by the multiconfiguration interaction method and fitted with the analytical form of the extended LEPS function. Attention was paid to the mean values of the vibrational and rotational quantum numbers of O2 molecules and their temperature dependence. The temperature dependence of the mean lifetime of the OOH collision complex was also examined. The calculated rate constants were analyzed and compared with the experimental data over the temperature region of the combustion processes.

scholarly journals Sources of Variability in the Response of Labeled Microspheres and B Cells during the Analysis by a Flow Cytometer

2021 ◽  
Vol 22 (15) ◽  
pp. 8256
Author(s):  
Adolfas K. Gaigalas ◽  
Yu-Zhong Zhang ◽  
Linhua Tian ◽  
Lili Wang
Keyword(s):  
B Cells ◽  
Laser Beam ◽  
Cross Section ◽  
Mean Fluorescence Intensity ◽  
Numerical Aperture ◽  
Flow Cytometer ◽  
Fluorescence Signal ◽  
Minor Importance ◽  
Reliable Measure ◽  
The Mean

A stochastic model of the flow cytometer measurement process was developed to assess the nature of the observed coefficient of variation (CV%) of the mean fluorescence intensity (MFI) from a population of labeled microspheres (beads). Several sources of variability were considered: the total number of labels on a bead, the path through the laser beam, the optical absorption cross-section, the quantum yield, the numerical aperture of the collection optics, and the photoelectron conversion efficiency of the photomultiplier (PMT) cathode. The variation in the number of labels on a bead had the largest effect on the CV% of the MFI of the bead population. The variation in the path of the bead through the laser beam was minimized using flat-top lasers. The variability in the average optical properties of the labels was of minor importance for beads with sufficiently large number of labels. The application of the bead results to the measured CV% of labeled B cells indicated that the measured CV% was a reliable measure of the variability of antibodies bound per cell. With some modifications, the model can be extended to multicolor flow cytometers and to the study of CV% from cells with low fluorescence signal.

Measurement of the Thermal Neutron Cross Section of the90Sr(n, γ)91Sr Reaction

1994 ◽  
Vol 31 (3) ◽  
pp. 173-179 ◽  
Author(s):  
Hideo HARADA ◽  
Toshiaki SEKINE ◽  
Yuichi HATSUKAWA ◽  
Noriko SHIGETA ◽  
Katsutoshi KOBAYASHI ◽  
...  
Keyword(s):  
Thermal Neutron ◽  
Cross Section ◽  
Neutron Cross Section ◽  
Thermal Neutron Cross Section

Proton spin thermometry and molecular dynamics of the liquid crystal PAA in the solid phase

1974 ◽  
Vol 61 (11) ◽  
pp. 4646-4649 ◽  
Author(s):  
R. T. Thompson ◽  
D. W. Kydon ◽  
M. M. Pintar
Keyword(s):  
Molecular Dynamics ◽  
Liquid Crystal ◽  
Solid Phase ◽  
Proton Spin
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