Topic
Absorption (logic)
About: Absorption (logic) is a research topic. Over the lifetime, 5733 publications have been published within this topic receiving 236302 citations.
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TL;DR: In this paper, the spectrum of molybdenum x-ray rays scattered by graphite at 45, 90, and 135 degrees were compared with the primary spectrum of the primary beam, and the difference in the wave-lengths increased with the angle between the primary and the scattered rays.
Abstract: The spectrum of molybdenum $\mathrm{K}\ensuremath{\alpha}$ rays scattered by graphite at 45\ifmmode^\circ\else\textdegree\fi{}, 90\ifmmode^\circ\else\textdegree\fi{} and 135\ifmmode^\circ\else\textdegree\fi{} has been compared with the spectrum of the primary beam. A primary spectrum line when scattered is broken up into two lines, an "unmodified" line whose wave-length remains unchanged, and a "modified" line whose wave-length is greater than that of the primary spectrum line. Within a probable error of about 0.001 A, the difference in the wave-lengths ($\ensuremath{\lambda}\ensuremath{-}{\ensuremath{\lambda}}_{0}$) increases with the angle $\ensuremath{\theta}$ between the primary and the scattered rays according to the quantum relation $(\ensuremath{\lambda}\ensuremath{-}{\ensuremath{\lambda}}_{0})=\ensuremath{\lambda}(1\ensuremath{-}cos\ensuremath{\theta})$, where $\ensuremath{\lambda}=\frac{h}{\mathrm{mc}}=0.0242$ A. This wave-length change is confirmed also by absorption measurements. The modified ray does not seem to be as homogeneous as the unmodified ray; it is less intense at small angles and more intense at large angles than is the unmodified ray.An x-ray tube of small diameter and with a water-cooled target is described, which is suitable for giving intense x-rays.
173 citations
TL;DR: In this article, the absorption cross sections of nine possible detectors of solar neutrinos were calculated using illustrative solar models and ad hoc assumptions about neutrino propagation, and the calculated cross sections were used to discuss what can be learned about the sun or weak interactions.
Abstract: New results are presented for absorption cross sections of nine possible detectors of solar neutrinos ($^{7}\mathrm{Li}$, $^{37}\mathrm{Cl}$, $^{51}\mathrm{V}$, $^{55}\mathrm{Mn}$, $^{71}\mathrm{Ga}$, $^{81}\mathrm{Br}$, $^{87}\mathrm{Rb}$, $^{115}\mathrm{In}$, and $^{205}\mathrm{Tl}$). Special attention is given to nuclear physics uncertainties. The calculated cross sections are used (with the aid of illustrative solar models and ad hoc assumptions about neutrino propagation) to discuss what can be learned about the sun or weak interactions from each of the nine suggested solar neutrino experiments. An experimental program for neutrino spectroscopy of the solar interior is outlined. It is shown in addition that stellar collapses can be detected to typical distances of several kpc (kiloparsecs) by the proposed $^{7}\mathrm{Li}$, $^{37}\mathrm{Cl}$, and $^{115}\mathrm{In}$ solar neutrino detectors (provided that electron neutrinos do not decay or oscillate).
171 citations
TL;DR: In this article, a redetermination of the zero-field hyperfine splitting of the ground state of atomic hydrogen was made using a microwave absorption technique employing a resonance line with a width of about 3 kc/sec.
Abstract: A redetermination has been made of the zero-field hyperfine splitting of the ground state of atomic hydrogen. A microwave absorption technique was used employing a resonance line with a width of about 3 kc/sec. This width (occasionally as narrow as $\frac{1}{10}$ of the normal Doppler breadth) was obtained through the mechanism of collision reduction of the Doppler effect. The primary relaxation mechanism was electron exchange between hydrogen atoms. The measured result for the hyperfine splitting is $\ensuremath{\Delta}\ensuremath{
u}=1420.40580\ifmmode\pm\else\textpm\fi{}0.00006$ Mc/sec.
170 citations
TL;DR: In this article, the electronic structure of aerogels is studied by soft x-ray absorption near-edge structure (XANES) spectroscopy, and the effect of short and long-range order on the electronic structures of these materials is discussed.
Abstract: The electronic structure of ${\mathrm{TiO}}_{2}$ aerogels is studied by soft x-ray absorption near-edge structure (XANES) spectroscopy. High-resolution O K-edge and Ti ${L}_{2,3}$-edge XANES spectra of aerogels are compared with those of rutile, anatase, and unrelaxed amorphous phases of full-density ${\mathrm{TiO}}_{2}.$ Results show that all the main spectroscopic features of aerogels, reflecting the element-specific partial density of empty electronic states and correlation effects, can be attributed to the absence of long-range order in stoichiometric amorphous ${\mathrm{TiO}}_{2}.$ Based on these results, we discuss the effects of short- and long-range order on the electronic structure of ${\mathrm{TiO}}_{2}.$
170 citations
TL;DR: In this paper, the authors analyzed the optical absorption data of paramagnetic salts containing [M(H 2 O)$O)$\6}, M = 3d$n}, and showed that the orbital level separations given by the optical spectrum are smaller than those predicted from magnetic data.
Abstract: The typical colours of paramagnetic salts containing [M(H$\_{2}$O)$\_{6}$], M = 3d$^{n}$, complexes, are generally assumed to arise from optical transitions between the orbital energy levels of the 3d ion which are split by the crystalline electric field due to the surrounding water dipoles. The available optical absorption data are analyzed using this ionic model and the associated crystal field theory, and it is shown that while experiment and theory agree fairly well, there are systematic discrepancies. In addition, the orbital level separations given by the optical spectrum are found to be smaller than those predicted from magnetic data. It is shown how these discrepancies can be accounted for by introducing weak covalent bonds into the [M(H$\_{2}$O)$\_{6}$] complex, so that there is charge transfer between the paramagnetic ion and the attached water molecules.
169 citations