Showing papers by "University of Mons published in 1972"

Spectres de photoélectrons X de composés solides de cuivre Relation entre la présence de raies satellites et l'état d'oxydation du cuivre

Abstract: L'etude comparative des spectres de photoelectrons X de composes de cuivre I et II, ainsi que l'examen des modifications apparaissant au niveau des raies du cuivre et de l'oxygene dans les composes de cuivre I suite a l'action de gaz actifs (O2, H2O), indiquent que la structure satellite adjacente aux raies du cuivre est specifique de l'ion cuivrique. Comparative study of the X-ray photoelectron spectra of copper I and II compounds, as well as an examination of the changes of copper and oxygen lines caused by active gases (O2, H2O) on copper I compounds, clearly show that the satellite structure adjacent to copper peaks, is specific of the cupric ion.

Structure and Reactivity of Chromium‐Doped Tricalcium Silicate

Abstract: The correlation between the structure and reactivity of Cr-doped tricalcium silicate was studied by ir spectrophotometry and X-ray diffractometry. A very sensitive method of detection of defects (thermostimulated exoelectron emission) allowed differentiation of three types of electron traps; the activation energy for the third trap was 0.8 eV. These crystal defects seem to be associated with sites of high Cr concentration (disordered structure) which may also be responsible for the increased reactivity of the doped phases. The reactivity of the system tricalcium silicate-H2O (w/c=0.6) was studied by an electrical conductometric method. Curves of conductivity vs time for tricalcium silicate with varied Cr concentrations indicated significant differences in hydration kinetics.

Observations spectroscopiques de HD 50138

Abstract: Observations of the Be star HD 50138 have been extended to the photographic infrared region up to 9500 A. The main features noted in this wavelength range are strong lines of Oi (8446 A), Hi (from P 9 to P 20), the Caii infrared triplet and the λ8629 line attributed to Ni. The λ7772 multiplet of Oi is shown to undergo important changes during the period of observations (1959–1971). Higher Balmer lines do not exhibit any emission component, but their profiles are variable and indicate the presence of satellite absorption, as already mentioned by some authors.

Early Data from the Ultraviolet Sky-scan Telescope in the TD1 Satellite

Abstract: An initial examination of data from the TD1 satellite telescope shows it to be functioning satisfactorily. The spectra observed are in good agreement with information obtained from rocket-borne telescopes.

Spectres de quelques étoiles Be entre 7000 et 9600 Å

Abstract: Kodak IM plates have been used in order to extend to 9600 A the observed wavelength range for 23 O, B, Be Bp and A stars. The spectra are shown in the plate. Several atmospheric absorption bands perturb the continuum and line spectrum. Between 1.45 and 1.20μ -1, we have measured the parameter d logI λ/d(1/λ). The results appear in the table and indicate that Be stars do not exhibit anomalous reddening in this spectral region. On the other hand the above parameter is much more sensitive to the reddening than to the star's effective temperature.

Spectre continu dans le proche infrarouge de deux étoiles Be: HD 50138 et HD 51585

Abstract: Continuous spectra of the Be objects HD 50138 and HD 51585 have been investigated between 1.6 and 1.2μ-1. The infrared gradientφIR of HD 50138 (B5eV) is found to be 2.09±0.10, while the typical B5V star π And indicatesφIR=1.17. A B5V (HD 16219) star located at about the same distance as HD 50138 hasφIR=1.29 and it is shown that interstellar reddening may account forΔφIR between HD 16219 and π And. The difference in gradient between HD 50138 and HD 16219 (ΔφIR=0.8) may be explained by a continuous reemission in a lenticular envelope with a radius equal to 4R*. The peculiar object HD 51585 exhibits a B0.5 continuous spectrum, for which the value d logIλ/d(1/λ) should be 1.13 according to model atmospheres computations. The distance as derived from color excess leads to disagreement between measured and computed (for a B0.5 star) values of d logIλ/d(1/λ). The reddening may be explained by reemission in an envelope the radius of which is smaller than 5R*. In conclusion, the narrowness of the spectral range under consideration does not permit to decide whether the observed reddening is due to recombination to the third level of the hydrogen atom or whether it is part a thermal reemission in a circumstellar cloud at lower temperature, as it has been observed around 10 μ by various authors.