Search results for "Deuterium"

Irradiation of nuclear materials with laser-plasma filaments produced in air and deuterium by terrawatt (TW) laser pulses

2017

Deuterium monolayers physisorbed on krypton-plated graphite: A two-dimensional Ising system

1997

Abstract Neutron-diffraction measurements were used for the first time to investigate the influence of the modification of the graphite substrate potential and of the susbrate symmetry caused by a preadsorbed layer of krypton (Kr). It will be shown that D2 on Kr/graphite presents a new 2D Ising system. The order-disorder transition of this system has been studied.

Localized Motion in Supercooled Glycerol as Measured by 2 H-NMR Spin-Lattice Relaxation and Incoherent Neutron Scattering

1991

Selectively deuterated glycerol has been subjected to 2H-NMR spin-lattice relaxation and quasi-elastic neutron scattering experiments. The measurements yield relaxation rates and a non-Gaussian Q-dependence of the Debye-Waller factor which are different for the two hydrogen sites. The data analysis shows that below the onset of the glass transition α-process the hydrogens perform a local motion (≈ 10-12 s) in addition to what is expected from harmonic phonons. The resulting mean-square displacements are highly temperature dependent but are significantly smaller than those found in van der Waals glasses. Amplitudes and activation energies of the carbon-bonded and oxygen-bonded hydrogens are …

Glovebox atmosphere detritiation process using gas separation membranes.

2003

Abstract The use of gas separation membranes in atmospheric detritiation systems has been studied. The main advantage of this new process is to reduce the number and/or the size of the equipment in comparison to conventional tritium removal systems. Owing to the constraints linked to tritium handling, the separation performances of several commercial hollow fiber organic membranes have been analyzed, under various operating conditions, with hydrogen/nitrogen or deuterium/nitrogen mixtures. The experiments are performed with small quantities of hydrogen or deuterium (5000 ppm). The experimental results allow to evaluate the separation efficiency of these membranes and to determine the approp…

Chiral mesophases of hydrogen-bonded liquid crystals

2020

The chiral induction in hydrogen-bonded liquid crystals is investigated. The experimental study was accompanied by detailed density functional theory calculations and variable-temperature solid-state deuteron NMR measurements indicating that interactions between the linking groups of the hydrogen-bond accepting unit play a key role in the chiral induction.

The Effect of Hydrogen (Deuterium) Activation During the Interaction with Some Transition Metal Surfaces*

1993

Isotope effects on the dynamics of a supercooled van der Waals liquid

2000

Deuteron magnetic resonance was used to study three differently isotope-labeled species of the fragile glass-forming liquid ortho-terphenyl. The calorimetric glass transition of the isotope deuterated only at the central phenyl ring is significantly lower than that of the perdeuterated one. It is shown that while the ortho-terphenyl molecule is not as rigid as previously often assumed, its overall reorientation geometry is independent of deuteration. The characteristic jump angles are found to increase with temperature, thus resolving an apparent discrepancy previously noted when comparing typical jump sizes from NMR with other data.

Detection of deuterium retention by LIBS at different background pressures

2017

ITER plans foresee the quantitative diagnostics of fuel retention in reactor walls at near-atmospheric pressures. Using laser induced breakdown spectroscopy (LIBS) for this purpose assumes a reliable resolving of Balmer α-lines of hydrogen isotopes in spectra of plasma produced by focused laser radiation onto the target surface. To develop LIBS for quantitative diagnostics of fuel retention during the maintenance breaks of ITER, the effect of background gas pressure on the laser-induced plasma characteristics has been studied. The background pressure limits the expansion rate of plasma and as a result it leads to higher plasma concentrations. At the same time the limiting factor of the reso…

1983

The neutron scattering from mixtures of deuterated and undeuterated poly(ethylene oxide), (D-PEO, H-PEO), in the small angle and intermediate angle region has been measured in the melt. We found no indications of a molecular segregation. The value of molecular weight evaluated agreed with that obtained by other methods. For a sample with a molar mass of 120000 g/mol the radius of gyration 〈rw2〉1/2 was found to be 13,6 nm, which corresponds to a characteristic ratio of C = 6,9. The form factor of a single chain can be described by the Debye equation for a random coil with the same unperturbed dimensions. Our results are compared with rotational isomeric state calculations and measurements in…

Hydrogen and deuterium decoration of In-vacancy complexes in nickel.

1987

The quantum-mechanical states of hydrogen and deuterium in pure and defected nickel have been calculated using the effective-medium theory. The defects considered include monovacancies, the substitutional In impurity, a complex of four vacancies, and a complex of an In impurity decorated with a tetrahedron of four vacancies. While the substitutional In impurity does not trap hydrogen, the vacancy and the vacancy complexes with and without In association do. The calculated binding energy to the four vacancy complex is nearly insensitive to the hydrogen isotopic mass and to the In decoration. These results, along with the dependence of the hydrogen binding energy on multiple hydrogen occupanc…