Bonding in uranium oxides: The role of 5f electrons

X-ray photoemission spectra of valence and bonding bands of UO₂, U₃O₈ and UO₃ are presented. The gradual transfer of localized 5f electrons into the bonding band as a function of oxygen content has been studied in these oxides.     

The possibility of using a semiconductor thermal probe to investigate the power flow distribution in waveguides

Conclusions

1. The temperature profile of an absorbing film for a given microwave power flux distribution has been considered.
2. The conditions under which agreement is found between the temperature relief and the flux distribution has been clarified.
3. An experimental investigation has been carried out of the temperature profile in a matched film for the TE₁₀ mode.
4. The possibility of using a semiconductor thermal probe to investigate the microwave power flux distribution has been demonstrated.

     

Evidence for shape deformations of fragments in deep inelastic collisions

The number and energy spectra of neutrons evaporated by the heavy and light fragments in deep inelastic collisions have been obtained for the system 240 MeV⁴⁰Ar +¹⁹⁷Au. They indicate that at the scission point the deformation energy is a large part of the total excitation energy espe cially for the light fragment. In the last two years, neutron emission has been studied in deep inelastic reactions^1?6. All the results are similar: the incident energy which is lost during the process is transformed into excitation energy of the final fragments and is shared between the two products proportionnally to their masses. This means that the nuclear temperature was uniform in the composite system. The excitation energy equilibration time is really very short since equilibration is achieved after reaction times as small as 10^?22 s^2,6. Moreover, no preequilibrium emission (direct neutrons-) has been observed.     

Argon (10 keV) scattered from structures,induced by bombarding a Cu(100) surface; ionization and neutralization

The ion fractions, η⁺, of 10 keV argon particles, scattered from a damaged copper surface, are measured with a time of flight spectrometer. The damage was introduced by bombardment with argon ions. The scattering angle was 30°. The results for different angles of incidence, ψ, are reported. For Ψ < 10° the ion fraction is relatively high (～27% for Ψ = 4°) and decreases as Ψ increases. For Ψ = 15° the value of η⁺ is 7%, whereas for 21° < Ψ < 27° the value of η⁺ appears to be constant (～14%). An explanation is given by assuming interatomic ionization as well as neutralization processes along the trajectory of the scattered particles. The number of step-atoms, induced by ion bombardment, is estimated to be about 2 × 10¹⁴/cm².     

Mixing transformations on metric spaces

It is proved that if a metric space is subjected to a mixing transformation, then there exists a positive numberx ₀ such that the probability that any arbitrary set of positive measure is asymptotically mapped into a set of diameter less thanx ₀ is zero. Physical implications of this result, in particular the interpretation of Poincaré recurrence, are discussed.     

Interferential microwave probe for measuring sea ripples

Summary A sea wave sensor, of new design, utilizing a teflon-coated microwave line and capable of measuring ripples up to 26 Hz is described, and its operation is analysed. Sea spectra in the short gravito-capillary domain are reported and discussed.

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Riassunto Si descrive un nuovo tipo di ondametro che utilizza una linea a microonde in filo rivestito di teflon ed è capace di misurare onde gravito-capillari fino alla frequenza di 26 Hz. Dopo aver analizzato la precisione della misura, si riportano alcuni spettri osservati in mare in regime di brezza.

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Резюме Описывается новый тип волнометра, в котором используется микроволновая линия, покрытая тефлоном и способная измерять капиллярные волны до частот 26 Гц. Анализируется точность измерений с помозью описанного микроволнового зонда. Приводятся некоторые спектры, наблюденные в море в режиме бриза.

     

Temperature dependence of the electric field gradient in CdSe and HfO2

The time differential perturbed angular correlation technique was applied to study the electric field gradient in the semiconductor CdSe and the insulator HfO₂ at different temperatures. Whereas the semiconductor CdSe shows an increasing quadrupole coupling constant with increasing temperature, the insulator HfO₂ exhibits no temperature dependence of the electric field gradient over the whole temperature range investigated.